300 009-149

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EMC® Symmetrix® VMAX™ Best Practices

Technical Notes P/N 300-009-149

REV A04 December 15, 2010

This technical note contains information on the following topics:

Executive summary ................................................................................... 2 Introduction ................................................................................................ 2 Symmetrix VMAX expansion fundamentals ......................................... 3 Tiered storage ............................................................................................. 6 Tiered storage best practices ................................................................... 17 Scaling Symmetrix VMAX capacity and performance ....................... 18 Data protection methods ......................................................................... 24 EMC Symmetrix Data at Rest Encryption ............................................ 30 Conclusion ................................................................................................ 30

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Executive summary

EMC Symmetrix VMAX Best Practices Technical Note

Executive summary

The EMC® Symmetrix® VMAX™ Series with Enginuity™ Operating Environment delivers the industry's only EMC Virtual Matrix Architecture™ and revolutionizes the high-end storage market to set Symmetrix apart from all other competitive offerings. It combines the ability to scale performance and capacity to unmatched levels with industry proven support for nondisruptive operations. These core capabilities are now combined with new features purpose-built for the next generation Virtual Data Center. Together, they enable IT organizations to reduce cost and deliver service levels through scale out, automatic storage tiering, and support of thin devices; provide management abstraction to enable ease, speed, and automation; encrypt data at rest, while delivering “24 x 7 x Forever” application availability and ease of use. The system is powered by the Enginuity operating environment to enable high-end functionality and data protection.

This technical note explains the major configuration options available for Symmetrix VMAX and makes recommendations to maximize the advantages of new levels of capacity and tiering capabilities available in this array.

Introduction

The Symmetrix VMAX system is an innovative platform built around a scalable Virtual Matrix™ design. It incorporates powerful new multi-core processors and can seamlessly grow from an entry level configuration into the world’s largest storage system.

Symmetrix VMAX delivers the highest levels of performance, featuring:

Support for 48 to 2,400 drives: Up to 10 storage bays 240 drives per bay

Support for 2 to 16 directors connected through a Virtual Matrix Connectivity: Fibre Channel, FICON, iSCSI, and GigE 2x the front-end ports of DMX-4

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Symmetrix VMAX expansion fundamentals


2x the back-end ports of DMX-4 Heterogeneous support for mainframe, UNIX, IBM i, and virtualized

hosts Symmetrix VMAX offers the ultimate in scalability, including the ability to incrementally increase back-end performance by adding Symmetrix VMAX Engines and storage bays. Each Symmetrix VMAX Engine controls eight redundant Fibre Channel loops that support up to 240, 360, or 600 drives depending upon configuration. Each Symmetrix VMAX Engine provides front-end as well as back-end connectivity.

Capacity and performance upgrades can be performed online while production applications are operating. In fact, all configuration changes, hardware and software updates, and service procedures are designed to be performed online and nondisruptively. This ensures that customers can consolidate without compromising availability, performance, and functionality, while leveraging true pay-as-you-grow economics for high-growth storage environments.

Audience

This technical note is designed to assist both customers and EMC personnel who configure, design, and order Symmetrix VMAX systems. The subjects presented will be of interest to technology professionals who desire an understanding of performance capabilities and EMC recommendations for maximizing utilization of the Symmetrix VMAX array.


The Symmetrix VMAX architecture introduces the highest level of scalable growth without increasing complexity for component identification or service actions. Consistency in expansion and the corresponding cable placement has been structured into the Symmetrix VMAX system. Interpretation of the storage bay labels shown in Figure 1 will reveal the available growth paths. The storage bay identifiers obey the following rules:

Direct connect bays are numbered 1 and daisy chained bays are numbered 2 or 3 (see storage bay numbering in Figure 1).

A, B, C, and D are used to identify the storage bays that share

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EMC Symmetrix VMAX Best Practices Technical Not

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Symmetrix VMAX Engine resources (Figure 1). Each storage bay is divided into an upper and lower half.

Symmetrix VMAX Engines in the upper half of the system bay are cabled to the upper half of the storage bays and Symmetrix VMAX Engines in the lower half of the system bay are cabled to the lower half of the storage bays. In this way cabling is controlled, consistent, and tidy through all configurations.

Symmetrix VMAX Engines in the system bay are populated from the centre position to the outside.

Figure 1 shows the largest Symmetrix VMAX unit with eight Symmetrix VMAX Engines and a full complement of 10 storage bays. From the labels shown in Figure 1 and the Symmetrix VMAX Engine numbers in the figure, we can see the direct/daisy chain bay and Symmetrix VMAX Engine relationship. The system must grow from the inside out.

System Bay

Storage Bay1B

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DaisyChain

DirectConnect

DaisyChain

DaisyChain

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DaisyChain

DirectConnect

Figure 1. Symmetrix VMAX bay identification (Front)

Extended Drive Loop Configurations

Extended Drive Loop Configurations provide customers with the option to grow their systems up to 10 storage bays with 2,400 drives with only four Engines installed. Extended Drive Loops are useful for customers who want to add capacity but do not need the additional processing power, cache, or connectivity ports. Figure 2 shows a fully populated Symmetrix VMAX with an Extended Drive Loop Configuration.

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DirectConnect

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StorageBay5B

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Figure 2. Symmetrix VMAX Extended Drive Loop Configuration (Front)

Fully configured Extended Drive Loop Configurations have fewer Engines than a fully configured Standard 2400 Drive Configuration. Therefore, they consume less power and cooling, and have a lower overall system weight. Extended Drive Loop Configurations also have fewer connectivity ports, less cache, and slightly less usable capacity than fully configured Standard Configurations.

Standard Configurations with up to four Engines and four Storage Bays (960 drives) can be converted to Extended Drive Loop Configurations. The customer has the ability to either add only Storage Bays to take advantage of an Extended Drive Loop Configuration, or add more Engines along with additional Storage Bays to follow the Standard Configuration. Conversion from Standard Configuration with more than four Engines to Extended Drive Loop Configuration is not allowed. Likewise, conversion from Extended Drive Loop Configuration to Standard Configuration is not allowed. Extended Drive Loop Configurations can also take advantage of Storage Bay Separation, following the same rules as Standard Configurations.

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Tiered storage


Tiered storage

For extremely performance-sensitive, mission-critical applications, it is possible to implement tiering using dedicated Symmetrix VMAX arrays for each tier. Dedicating all system resources to the tier 0/1 applications eliminates any possibility of tier 2 applications impacting tier 1 service-level agreements (SLAs).

Most customer environments contain a mix of workloads and are under powerful cost imperatives to consolidate multiple applications with different Service Level Objectives (SLO) within a single Symmetrix VMAX system. The Symmetrix VMAX array is equipped with hardware and software to support exactly this kind of application consolidation. Two or more applications with different SLOs may reside within a single Symmetrix VMAX array but be configured on different drive types and protection types to meet the differing workload demands. EMC Enginuity facilitates the movement of data between Symmetrix tiers, including drive and RAID type changes, and offers additional dynamic configuration options for speed and management efficiency. With FAST and FAST VP, automated tiering in an array is dynamic and timely, with easy management. The following sections describe several configuration options for implementing tiered storage. Appropriate drive choices as well as use of new management tools will deliver the highest performance and lowest cost with best predictability for critical tier 0/1 applications while also providing differentiation in cost and performance for less-critical tier 2 applications.

Tiered storage in dedicated arrays

Tier 0/1 applications are characterized by high I/O rates. Prior to Enterprise Flash Drives, the maximum system performance in these environments was achieved with fewer drives per loop and smaller drive sizes with faster speeds (for example, 146 GB 15k rpm). As tier 0/1 capacity and performance requirements increase, additional Symmetrix VMAX Engines can be added. Symmetrix Optimizer will balance the system to maintain the highest system performance within a Symmetrix tier. Enterprise Flash Drives introduced the “Tier 0” concept of an

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Tiered storage


ultra-performance application tier that transcends the limitations previously imposed by magnetic disk drives. Implementation of Flash drives is discussed later in this document.

Separate arrays can be dedicated to tier 2 applications, which generally have an I/O profile that does not push back-end performance. In these environments, larger drive capacities such as SATA drives become appropriate.

Figure 3 illustrates tiered storage across multiple dedicated arrays.

Multiple Use Cases - Multiple Service Levels - Multiple Cost Points

Figure 3. Tiered storage across dedicated arrays

Tiered storage within a high-end array

Segregating tiers

Tiering across dedicated arrays is of course available for the Symmetrix VMAX, but tiering storage within an array is a far more cost-effective operational model. The Symmetrix VMAX system is specifically designed with hardware and software to support in array tiering. Two

RAID 5

10k RPM

Business-critical applications

(tier 2)

Enterprise Flash Drives

Ultra Performance

Backup, recovery, and archive

Mission-critical

(tier 3)applications

RAID 1 RAID 6

15k RPM 7,200 RPM

Common Platform - Common Management - Common Protection

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Tiered storage


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or more applications residing within a single Symmetrix VMAX can be configured on different drive types and protection schemes to meet differing workload demands. FAST and FAST VP facilitate the movement of data between Symmetrix tiers, contain additional dynamic configuration options for speed and management efficiency, and provide common functionality to deliver value for tiering.

One possible implementation of tiered storage within a single Symmetrix VMAX system is to isolate the Symmetrix tiers in separate groups of disk enclosures (by Symmetrix VMAX Engine). For example, certain Symmetrix VMAX Engines may contain slower (high capacity) drives and others may have faster (high performance) drives, as illustrated in Figure 4. This configuration delivers predictable performance by separating disk resources for each tier.

In Figure 4 we see all the same drive types assigned to a Symmetrix VMAX Engine. Predictable performance is available because workloads are segregated, but the segregation reduces total performance by restricting the total resources available for each tier.

DAE group

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VMAX Engine 4, dir 7 and 8

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Enterprise Flash drives

Single tier per DAE

VMAX Engine 5, dir 9 and 10 VMAX Engine 6, dir 11 and

10k rpm drives


10k rpm drives

Figure 4. Tiers segregated by DAE group (Engine)

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Tiered storage


Mixing drives throughout the system without segregating

In preference to segregation of tiering resources within the Symmetrix VMAX array, spread the different types of drives throughout the system. Figure 5 shows an array with no special attention paid to intermixing drive speeds and capacities. This configuration maximizes the director resources available for any tier and delivers the highest total performance to all applications. The management tools discussed in the following sections—Fully Automated Storage Tiering (FAST), Symmetrix Priority Controls, Dynamic Cache Partitioning, and Enhanced Virtual LUN technology—can be deployed to fine-tune system resources and define priorities.

FAST automates tiered storage by easily moving workloads between Symmetrix Tiers as performance characteristics change over time. FAST performs system reconfiguration, improving performance, and reducing costs, all while maintaining vital service levels.

Symmetrix Priority Controls provide the ability to prioritize back-end I/O by device group, ensuring preferential processing, while Dynamic Cache Partitioning makes performance more predictable by isolating memory resources by device group.

Virtual LUN enables users to nondisruptively relocate volumes to different drive types and RAID types transparently to the host and without impacting local or remote replication. Organizations can respond more easily to changing business requirements when using tiered storage in the array.

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Tiered storage


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DAE group

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d i


Flash +

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VMAX Engine 5, dir 9 and

Tiering independent

of DAE groupFlash +

15k rpm

Figure 5. Different drive types mixed throughout the system

Fully Automated Storage Tiering

Fully Automated Storage Tiering (FAST), for standard provisioned environments automates the identification of data volumes for the purposes of allocating or re-allocating application data across different performance/capacity tiers within an array. FAST proactively monitors workloads at the volume (LUN) level and in order to identify “busy” volumes that would benefit from being moved to higher performing drives. FAST will also identify less “busy” volumes that could be relocated to higher capacity drives, without existing performance being affected. This promotion/demotion activity is based on policies that associate a storage group to multiple drive technologies, or RAID protection schemes, based upon the performance requirements of the application contained within the storage group. Data movement

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Tiered storage


executed during this activity is performed nondisruptively, without affecting business continuity and data availability.

The primary benefits of FAST include:

Automating the process of identifying volumes that can benefit from Enterprise Flash Drives or that can be kept on higher capacity, less expensive SATA drives without impacting performance

Improving application performance at the same cost, or providing the same application performance at lower cost. Cost is defined as: acquisition (both hardware and software), space/energy, and management expense

Optimizing and prioritizing business applications allowing customers to dynamically allocate resources within a single array

Delivering greater flexibility in meeting different price/performance ratios throughout the lifecycle of the information stored

FAST VP

FAST VP with Enginuity 5875 extends the current FAST capabilities to include both thick (standard) devices and thin (virtually provisioned) devices. Building on the original version of FAST, EMC now offers sub-LUN data movement for thin devices providing increased capacity utilization.

Only a small portion of any LUN is actively supporting the workload I/O activity. Providing sub-LUN data movement at a much more granular level (smaller pieces), means production workloads can enjoy the benefits of improved performance and improved capacity utilization. For example, sub-LUN FAST can experience the benefits of improved performance from placing data on Enterprise Flash Drives (EFD) while using fewer EFD. Since a majority of the data is low activity data (due to the workload skew), it can be placed on the FC and SATA drives preserving performance while saving cost. Providing sub-LUN data movement at a much more granular level extents, allows FAST to be more responsive to changes in the production workload activity:

Improving performance Efficiently utilizing capacity

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Tiered storage


Requiring fewer EFDs in the system Allowing more data to be placed on SATA

FAST Management

Management and operation of FAST and FAST VP is provided by Symmetrix Management Console (SMC), as well as the Solutions Enabler Command Line Interface (SYMCLI). Also, detailed performance trending, forecasting, alerts, and resource utilization are provided through Symmetrix Performance Analyzer (SPA). EMC Ionix™ ControlCenter® provides the capability for advanced reporting and analysis to be used for chargeback and capacity planning.

Virtual LUN technology

Enhanced Virtual LUN feature now supports nondisruptive movement of Virtually Provisioned volumes between Virtually Provisioned Thin pools and RAID types, improving flexibility to meet changing business requirements in Virtually Provisioned, tiered arrays. Virtual LUN can be used to migrate thin volumes between thin pools, thereby freeing up storage in the source thin pool or changing the underlying protection or technology for a set of thin volumes according to the changing business needs. Enhanced Virtual LUN delivers the following benefits:

Improves storage optimization within the array Easy response to changing business requirements

Thin volumes underlying protection and disk type can be changed nondisruptively

Transparent operation by maintaining the same Symmetrix device ID across pool migrations

Complements the FAST offering by providing a convenient way to reverse FAST actions

Symmetrix Priority Controls

Many strategies currently exist to deliver improved performance for disk drives within storage subsystems. Cache memory, prefetching, disk level buffering, and request reordering are techniques that have evolved to address disk optimization opportunities inherent in storage

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Tiered storage


throughput operations. Faster seek times, higher disk spin rates, and reduced interface overhead attempt to counterbalance disk capacity increases and deliver improved access performance. All of these techniques function well in homogeneous environments. Universally employing high-speed drives is one way to guarantee that important workloads meet all expectations. Universally high performance may not be what is required or cost-effective for all applications. There is a place for low-priority workloads running concurrently with high-priority applications, when those workloads do not contend on the shared disk resources.

Symmetrix Priority Controls (SPC) offer the ability to manage multiple application workloads by preferentially allocating disk resources to higher-tier applications during times of disk contention of thick devices. Currently SPC is not available for Virtual Provisioning TDEV/TDATs. SPC will maintain multiple workloads cost-effectively within one consolidated storage unit and thereby satisfy tiered storage objectives. Preferential treatment of workloads at the disk level delivers:

Higher I/O rates on the disk while maintaining response time for priority work

Consistent response times for priority workloads Balanced disk utilization through workload peaks and troughs Greater disk utilization More effective use of larger capacity, lower performance disks Simultaneous low priority work with minimal contention on higher

priority work The opportunity now exists to meet organizational mandates for consolidation and cost reduction through this disk tiering infrastructure. Symmetrix Priority Controls provide flexibility to dictate the priority of application read I/O on a disk, by assigning volumes on that disk to the appropriate priority level required by their application. During times of congestion on a particular disk, Priority Controls become active, ensuring that volumes identified as high priority have preferential access to that disk.

Symmetrix Priority Controls provide enhanced support for IBM Workload Manager for z/OS (WLM) by responding to priorities provided by WLM in channel programs.

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Tiered storage


Priority Controls map disk priority settings contained in the Define Extent command to the appropriate level within their own hierarchy.

Dynamic Cache Partitioning

Cache resource optimization based on workload equality is the default behavior for Enginuity, catering to homogeneous application environments. As the trend continues to consolidate dissimilar workloads onto the same cache resource, flexibility for differential treatment between workflows becomes more desirable. The ability to set allocation preferences for cache memory facilitates many storage management objectives.

Workloads sharing memory and using partitioning techniques exhibit higher cache utilization than without partitioning and in some cases deliver performance improvements. Consider an example where two workloads acquire all available cache slots. One workload has no slot reuse, and no requested data is ever available in cache. The other workload has a cache hit rate of 100 percent, constantly finding the necessary data in cache. In one instance with no data reuse, cache utilization will be zero; for the other workload cache utilization will be 100 percent.

Mixing these workloads in the same cache resource would result in a total utilization number that is diluted by the average hit rate of the disparate workloads. Segregating these workloads into independent cache pools, however, produces separate utilization figures for each pool, and if correctly sized, the pools for each workload can produce performance improvements. Currently cache memory costs are many times that of disk, so small improvements in cache utilization are worthwhile and can result in potentially large cost benefits. Implementing segregation and partitioning introduces an opportunity for optimization through these interrelated variables:

Absolute size of the cache partition Size of the cache partition relative to the total cache resource

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Tiered storage


Changes to the size of the cache partition over the working day If a Meta workload is found to be flooding cache and hitting the

Write Pending (WP) limit, then Dynamic Cache Partitioning (DCP) could be deployed to isolate the Meta that could be causing WP issues

Workloads that are cache friendly can be allocated more cache resources, increasing the aggregate utilization figure and the performance of activities. Workloads that are not cache effective can be fenced in their own small cache partition, removing their diluting influence from other applications while still maintaining a low risk that their own performance is diminished. The resulting increase in aggregate cache utilization improves the effective use of cache and allows maximal performance for the cache-friendly workload. As application workloads change over the business day, the cache partitions can adapt, continually providing cache optimization for the workload mix currently dominant on the storage array. Appropriately configured flexible partitions that share unused cache based on application demands and business cycles can improve cache utilization and application performance.

Separate from performance optimization strategies, Dynamic Cache Partitioning can also create static partitions for cache resource containment and chargeback control. For example, paying subscribers can be guaranteed exclusive access to a static cache partition. Resource allocation management is simple and costs can be precisely apportioned. Dynamic Cache Partitioning (DCP) allows customers to adjust cache memory resources available to device groups configured in the Symmetrix. With cache partitioning enabled, users can create up to eight cache partitioning groups (CPGs), seven user defined and one default. Devices relevant to particular workloads can then be allocated a partitioned portion of Symmetrix cache. The cache subsystem is aware of the user-defined allocations and ensures that CPGs do not consume more cache than they are allotted. Each partition will have a target cache percentage as well as a minimum and maximum percentage. Partitions can be static or dynamic. Dynamic partitions allow donation of underutilized cache slots to other partitions where "underutilized" is user defined through the donation time. If the workload of a donating partition increases, donated slots will quickly return to meet that partition’s target requirement.

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Tiered storage


The user can enable or disable cache partitioning, create, modify, or move cache partitions, as well as add devices to or remove devices from cache partitions.

It is important to note that the WP limit for a flexible partition never changes with variations in the size of the partition. The WP limit is always calculated from the partition target value. This allows predictable behavior for features such as EMC SRDF®/A in a cache partitioned environment.

Symmetrix Virtual Provisioning

Symmetrix Virtual Provisioning™ is based on a technology commonly known in the industry as thin provisioning, whereby more capacity can be presented to a host than is used at the outset and multiple thin devices or applications can consume storage only as needed from a common thin pool.

When used appropriately with the right applications and workloads, Symmetrix Virtual Provisioning can provide the following benefits:

Simplified storage management Improved capacity utilization

Ease and speed of provisioning

Virtual Provisioning allows storage to be provisioned independently of the physical storage infrastructure. By creating a thin device that initially is larger than required by the application, organizations can reduce the need to re-provision new storage later on. With Virtual Provisioning, the underlying physical storage is consumed automatically only as needed. Virtual Provisioning also simplifies data layout with automated wide striping, and reduces the steps required to accommodate growth because capacity can be added to a pool without introducing more mapping and masking requirements.

Improved capacity utilization

When used with the appropriate applications, Virtual Provisioning can reduce the amount of unused physical storage by having multiple thin devices share a

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Tiered storage best practices


single thin pool, drawing physical storage from it only as needed. Storage administrators can reduce or avoid the pre-allocation of physical storage to applications thereby reducing storage costs and energy consumption. After migrating standard storage over to thin pools, users are able to reclaim unused storage from the target thin volume, further improving capacity utilization. A similar benefit is provided with EMC TimeFinder®/Clone thick-to-thin replication, which copies only host-written tracks to the target thin volume. Users can also automatically rebalance workloads nondisruptively in order to extend thin pool capacity in small increments as needed, maximizing performance and minimizing TCO.

Tiered storage best practices

Eliminate interaction between tiers

For extremely performance-intensive, mission-critical applications, it is important to dedicate all system resources to the tier 0/1 data and eliminate any possibility of interaction with tier 2 data. For this type of application profile, dedicating arrays to each tier may be appropriate. Figure 3 demonstrates this philosophy.

Dedicating entire arrays to a tier may not be the correct cost-effective solution for all situations. Implementing tiered storage within an array has cost benefits and can be configured to eliminate interaction between tiers. As shown in Figure 4, segregating Symmetrix VMAX Engine resources will achieve tier isolation and this configuration maximizes performance predictability for each tier.

Maximize all tiers

To maximize the performance of all applications, tiers should be distributed across all available Symmetrix VMAX Engine resources as in Figure 5. However, in this situation, the behavior of tier 2/3 applications must be well understood to ensure that they will not interfere with tier 1 applications. For example, working sets could be separated in time where tier 0/1 runs in the day and tier 2/3 runs at midnight.

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Scaling Symmetrix VMAX capacity and performance


Dynamic Cache Partitioning could be used to prevent lower-tier applications from impacting cache resources for higher-tier applications. In contrast, lower tier cache friendly workloads could be given more cache reducing their back-end operations while a back-end intensive tier 1 application was active.

Symmetrix Priority Controls could be utilized to assign priority to critical application volumes contending at the disk level.

Tiering versatility

FAST can dynamically move workloads between Symmetrix tiers as the performance requirements of the data and applications change. Volumes can dynamically move between drives of different capacity and spin rates and also between RAID types. Changing RAID protection is another facet to the response time/capacity balance.

Symmetrix Virtual Provisioning can be used to improve ease and speed of provisioning storage, increase disk utilization, and reduce capacity management costs. Certain applications may also see a performance benefit due to the wide striping across the data device storage pool.


Symmetrix VMAX can incrementally scale both capacity and back-end performance. If a system is initially configured with fewer than eight Symmetrix VMAX Engines, additional Symmetrix VMAX Engines can be added to increase performance and to support extra storage bays. These upgrades can be performed online while production applications are operating.

Each Symmetrix VMAX Engine uses eight redundant Fibre Channel loops. Each loop supports from 5 to 75 drives, depending on configuration. A fully configured Standard Configuration of the Symmetrix VMAX platform has more direct connect storage bays than previous platforms. Ultra–high-performance applications that require the fastest HDD drives (15k rpm) or use Enterprise Flash Drives can be placed on any Symmetrix VMAX Engine as the Symmetrix VMAX expands.

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Symmetrix VMAX scaling best practices

The best practices for Symmetrix VMAX scaling are: Add Symmetrix VMAX Engines and drives as storage and capacity requirements grow. Loop length is not an area of concern for Symmetrix VMAX growth planning.

4 Gb/s back-end support

Symmetrix VMAX supports a 4 Gb/s link speed. All hard disk drives and Flash drives are 4 Gb/s capable.

Drive choices

Symmetrix VMAX systems offer many choices for drive capacity and performance characteristics. Enterprise Flash Drives are available to provide maximum performance for latency sensitive and many other types of application.

Fibre Channel drives are offered in various capacity and rotational speeds. High-capacity SATA II drives can be seamlessly included in Symmetrix VMAX arrays for consolidating backup-to-disk and lower-tiered applications.

The following sections describe the performance characteristics of each type of drive and give some use case examples and configuration recommendations.

Fibre Channel and SATA II drives (HDD)

It is well understood that 15k rpm drives perform better than 10k rpm drives, which perform better than 7200 rpm drives. Seek time and rotational latency significantly affect the performance of the storage subsystem to attached hosts. Drives of the same rotational speed, latency, and seek time will have roughly equivalent performance, regardless of the drive capacity.

Current drive selections provide 10k and 15k Fibre Channel and 7.2k SATA speed rotational drives in addition to Enterprise Flash Drives.

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Serial Advanced Technology Attachment drive opportunities

The Symmetrix VMAX hardware platform maximizes the use of Serial Advanced Technology Attachment (SATA) II drives as recommended for:

Applications with sequential I/Os Applications that are cost sensitive and where the performance

requirement is bandwidth Write once, read many applications (DSS, data warehouse) Applications with low I/O workloads Nonauthenticated online media archive General purpose shared file systems Print queue storage Test environments

Adding lower tiers of storage to a tier 0/1 Symmetrix VMAX configuration using large capacity SATA drives enables customers to simplify management and standardize on Symmetrix functionality. Once customers have consolidated applications onto a Symmetrix VMAX array they can take advantage of the advanced business continuity and system availability features. Symmetrix VMAX with SATA drives affords customers a powerful and flexible choice for deploying lower-tier storage.

A number of high-level rules are available for the following replication feature sets to correctly take advantage of SATA drives.

For TimeFinder:

SATA drives can be used as targets with TimeFinder/Clone. Executing the precopy operation to completion before activating the clone will improve copy time and is considered a best practice. Note that the precopy operation may take longer on a SATA drive

SATA drives can be used as targets with TimeFinder/Emulation

For SRDF:

SATA drives can be used in SRDF relationships with other SATA drives

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SATA drives can be used as SRDF/S target volumes for non-SATA source volumes when used by read-intensive applications that generate few writes

SATA drives generally should not be used as SRDF target volumes for write-intensive applications

SATA drives are not to be used in tier 1 mission-critical applications where availability and performance are of significant importance. Examples of when not to use SATA include the following: online transaction processing (OLTP), Exchange/Notes/SMTP e-mail repositories, I/O-intensive decision support, or other applications or environments that would create a constant I/O demand on the drives. SATA drives should not be used for save device or SRDF/A Delta Set Extension (DSE) pools.

Performance as a function of drive count

It is important to remember that as the drive capacity increases within a particular family of drives, the performance per physical drive does not increase. When comparing a 146 GB 15k rpm drive against a 300 GB 15k drive, the capacity doubles, but the access density, or the number of I/Os per gigabyte that the drive can perform, is cut in half. When preparing a configuration proposal, it is often more important to consider the number of drives required for performance rather than to calculate for the required capacity.

To determine exactly the number of physical drives required, it is necessary to evaluate the back-end requirements of the workload. EMC’s standard performance tests show how system performance scales using different workloads with varying read and write profiles to simulate business environments such as Microsoft Exchange, Oracle databases, decision support systems, and data warehouse applications. These can be used to provide an estimate of the number of drives needed for a given application workload.

EMC Technical Representatives have tools that can model the utilization of a proposed system with a consolidated workload, to ensure that the appropriate number of physical drives is configured. The customer must provide Performance Manager or Symmetrix Trends of Performance (STP) data gathered from Symmetrix systems during peak times in order for the model to provide correct output.

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Enterprise Flash Drives

Enterprise Flash Drives provide maximum performance for many applications. Flash drives, also referred to as solid state drives (SSD), contain no moving parts and appear as standard Fibre Channel drives to existing Symmetrix management tools, allowing administrators to manage Tier 0 without special processes or custom tools. Tier 0 Flash storage has been found to improve a large number of applications. Obvious candidates for Flash drive are those with high transaction rates requiring the fastest possible retrieval and storage of data, such as currency exchange and electronic trading systems, or real time data feed processing. But even applications with high cache hit rates have been found to benefit substantially from Flash drives as every back-end access is satisfied with no latency or contention.

Enterprise Flash Drives deliver single-millisecond application response times and up to 30 times more IOPS at reasonable response times than traditional 15,000 rpm Fibre Channel disk drives. Additionally, because there are no mechanical components, Flash drives require up to 98 percent less energy per IOPS than traditional disk drives.

Enterprise Flash Drive storage can obviously benefit such applications as online transaction processing (OLTP), accelerating performance for I/O to large indices, and frequently referenced database tables. Examples of OLTP applications include Oracle, DB2 databases, and SAP R/3. Flash drives can also improve performance in batch processing and shorten batch processing windows. Flash drive performance will help any application that needs the lowest latency possible. Examples include:

Algorithmic trading Currency exchange and arbitrage Trade optimization Real-time data/feed processing Contextual web advertising Other real-time transaction systems Data modeling

Enterprise Flash Drives are advantageous in environments where disk access patterns show high counts of random read misses (RRM). If the

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RRM percentage is low, Flash drives may show less benefit since writes and sequential reads/writes already leverage Symmetrix cache to achieve the lowest possible response times. An EMC SPEED Guru can be engaged to conduct a performance analysis of the current workload and determine possible benefits from Flash drives.

Write response times of long distance SRDF/S replication could be high relative to response times from Flash drives. Flash drives cannot help with reducing response time due to long distance replication. However, read misses still enjoy low response times. Flash drives can be used as Clone source and target volumes. Flash drives can be used as SNAP source volumes. Virtual LUN migration supports migrating volumes to and from Flash drives. Flash drives can be used with SRDF/S and SRDF/A. Metavolumes can be configured on Flash drives as long as all of the logicals in the metagroup are on Flash drives.

A Symmetrix VMAX system can be upgraded to contain Enterprise Flash Drives at any time. The Flash drive is hot pluggable like a standard Fibre Channel drive. Flash drives are available in 200 GB and 400 GB capacities using the 4 Gb/s link speed. Organizations deploying Flash drives in a Symmetrix VMAX must create homogeneous RAID groups with Flash drives; all members of a RAID group must be configured on Flash drives.

Enterprise Flash Drives can be mixed with Fibre Channel and SATA II disks in the same array to consolidate storage tiers. In order to optimize the user benefits, Symmetrix internal volumes (Power Vault and Symmetrix File System) cannot be configured on Flash drives. Therefore, HDDs are required for each loop. The HDDs used as vault drives may be configured with host devices and more hard drives may be added to the loops that contain Flash drives. However, when intermixing applications on Flash drives with applications on HDDs on a single back-end loop, careful performance analysis of the specific applications involved should be conducted beforehand to prevent high-HDD activity from detracting the Flash drive’s benefits.

Flash drives participate in permanent sparing using Flash drive spares. Symmetrix Enginuity will block sparing between unlike media to avoid potential performance issues. The standard sparing requirements for HDDs will not change if Flash drives are installed in the same quadrant.

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Data protection methods


Vault devices and SFS devices cannot be configured on Flash drives.

For specific configuration rules, consult your EMC Sales Representative.

The EMC Symmetrix DMX-4 Ultra-Performance Tier 0 Using Flash Drives white paper available on http://www.EMC.com provides more information on Flash drives.


RAID Virtual Architecture

RAID Virtual Architecture (RVA) is a new architecture employed in the Symmetrix VMAX to implement RAID protection. RVA extends the design of RAID 6 used in the Symmetrix DMX-3 and DMX-4 storage arrays and in so doing provides a uniform implementation of all RAID protection schemes—unprotected, RAID 1, RAID 5, and RAID 6. The RVA design abstracts all RAID protection types to a single mirror position for a given Symmetrix logical volume, freeing up a device mirror position for additional features, such as Virtual LUN migration.

As before, each Symmetrix logical device is represented in the array by four mirror positions—M1, M2, M3, and M4. However, in Enginuity 5773 and earlier, certain RAID types—RAID 1 and RAID 5—used two mirror positions, as shown in Figure 6.

http://www.emc.com/

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Figure 6. Enginuity 5773 local RAID protection types

With Symmetrix VMAX, all local RAID protection types only consume one mirror position, as shown in Figure 7. Additionally RAID Virtual Architecture temporarily allows for two distinct RAID groups to be associated with a device. This feature allows for a Symmetrix logical volume to be migrated from one RAID group to another.

Figure 7. VMAX with Enginuity local RAID protection types

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RAID 1 (mirroring)

The EMC recommendation for highest performance is to use RAID 1 (mirrored) protection. RAID 1 configurations have higher performance in most applications because mirroring leads to a high disk count giving more read/write heads, and also with mirrored protection a random write only needs two simple disk operations where other RAID schemes require at least four disk I/Os plus parity calculations. Mirrored volumes will also have lower response time due to the Symmetrix Dynamic Mirror Service Policy (DMSP), which automatically determines the optimal disk to read to achieve maximum performance. In general, a mirrored configuration will perform as much as 30 percent better than a parity-protected (RAID 5) configuration with the same number of disks.

Mirrored configurations also provide higher performance if there is a disk failure since another complete copy of the data is immediately available. Furthermore, since only two disks are used for the mirror, the chance of multiple-drive failure is reduced. RAID 1 volumes are protected by permanent sparing.

RAID 5

RAID 5 configurations are parity-protected. In the event of a physical drive failure, the missing data is rebuilt by reading the remaining drives in the RAID group and performing XOR calculations.

RAID 5 may offer excellent performance for many applications since data is striped across back-end disk directors, as well as disks. However, there can be a performance disadvantage for write-intensive, random workloads due to the extra disk operations and the parity generation. RAID 5 can be configured with either four members 3+1 RAID 5 or eight members 7+1 RAID 5 in each RAID group. In most cases, the performance of 3+1 RAID 5 and 7+1 RAID 5 will be similar.

If a drive failure occurs for a larger RAID group on a bigger physical drive (with a longer rebuild time), there is an increased chance of a second drive failure during the rebuild. RAID 5 volumes are protected by permanent sparing.

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RAID 6

Protection schemes such as RAID 1 and RAID 5 can shield a system from data loss in the case of a single physical drive failure within a mirrored pair or RAID group. With these schemes, an array containing 10 RAID groups can tolerate 10 drive failures if only one drive in each RAID group fails. But what if two drives of the 10 failures are within the same RAID group? RAID 6 takes parity protection a step further and supports the ability to rebuild data in the event that two drives fail within the same RAID group.

EMC’s implementation of RAID 6 calculates two types of parity in order for data to be reconstructed following a double drive failure. Horizontal parity is identical to RAID 5 parity, which is calculated from the data across all the disks. Diagonal parity is calculated on a diagonal subset of data members.

RAID 6 provides high data availability but as with any multiple parity implementations, it is subject to parity generation impacting write performance. Therefore, RAID 6 is generally not recommended for write-intensive workloads.

Permanent sparing is used to further protect RAID 6 volumes.

Unprotected

Unprotected volumes have only one instance of the data. This protection method was typically reserved for short-term (for example, daily) backups/BCVs or test data, but this is no longer recommended due to the addition of RAID 5 BCVs. Failure of an unprotected BCV could cause significant delay in backups. EMC requires an approved RPQ for unprotected standard volumes.

Comparison of data protection methods

Table 1 is a high-level, general overview of the advantages and disadvantages of each protection method. Before deciding on the best protection method for a specific application, careful performance analysis should be conducted. The EMC Symmetrix VMAX Best Practices Technical Note provides details of specific applications that may create some caveats to the general performance characteristics listed in Table 1.

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Table 1. Comparison of data protection methods

RAID 1 RAID 5 RAID 6

Availability Better Good (more members) Best (dual parity protection)

Performance Best Better (parity generation) Good (dual parity generation)

Optimizer settings

With the Symmetrix VMAX platform, the entire optimizer swap process and definition of RAID groups are under RVA architecture. The historical flags for “Maintain RAID Groups” and “Maintain Mirrors” are no longer required.

Sparing

Symmetrix VMAX systems have a disk sparing functionality that reserves drives as standby spares. These drives are not user-addressable. The collection of spare drives is called the spare pool. Sparing increases data availability without affecting performance. Symmetrix VMAX systems utilize permanent sparing.

Permanent sparing

Permanent sparing will look for a spare drive of the same block size, capacity, and speed in a good location to permanently replace the failing drive through configuration change. Permanent sparing is used in combination with all protection types.

The process identifies a good location using the following rules:

No members of the same RAID 5 group on the same loop No more than two members of the same RAID 6 group on the same

loop

The failed drive becomes a not ready spare in the spare pool and can be replaced at a later time. There should be other spares available in the event of another drive failure. Any permanent sparing event that cannot be satisfied with available spares will initiate a demand service event.

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Any permanent sparing event that consumes the last available drive of a given type will initiate a demand service event.

Permanent Sparing of vault drives

Symmetrix VMAX systems are configured with five vault drives on each back-end Fibre Channel loop, which is one more vault drive per loop than Symmetrix DMX-4. Symmetrix VMAX with Enginuity allows permanent sparing to relocate the contents of one vault drive on each fibre loop to a suitable spare drive on another disk director in the system. This ability greatly enhances the capabilities of permanent sparing by increasing permanent sparing coverage for the vault drives in the system. Permanent sparing can relocate the remaining vault drives across the loops on the same disk director if a suitable spare drive is available.

Configuring spares

Spare drives are required for every Symmetrix VMAX system. Enginuity prevents creation of Symmetrix VMAX configurations that do not contain the required amount and type of spare drives. All drive types must be considered where capacity, speed, and block size constitute different drive types. A valid pool of spares for each drive type must be available.

The EMC ordering system will calculate the minimum amount of spares that should be configured in the Symmetrix VMAX. The rules for the amount and types of spares are as follows:

Hard drive sparing rules

Two spare drives for every 100 physicals of each drive type Minimum of eight spare drives for the entire system

Enterprise Flash Drive sparing rules

One spare for every 32 drives per type (size) If greater than 32 drives, use the hard drive sparing rule (2 per 100) Flash spares do not count towards the hard drive minimum of 8

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EMC Symmetrix Data at Rest Encryption


Additional spares of each type of drive can be added to further increase the chances of successful permanent sparing for each drive failure that may occur.

EMC Symmetrix Data at Rest Encryption

Drive Encryption

In many situations it is best practice to protect data on the disk drives to prevent unauthorized access to sensitive client data. EMC Symmetrix Data at Rest Encryption offers complete security for the drives with a minimum of management overhead for customers. Data encryption on the Symmetrix VMAX with Enginuity offers distinct advantages in the industry and is something to consider for any new system being installed at a site:

Unique key for every drive

Spared or replaced drives have their key “shredded” Internal key management with no backdoor to security Multiple encrypted copies of keys ensures no loss or management

problems No knobs or controls—complete ease of use

No special drives needed—all Symmetrix drives are supported by encryption—current and future

Does not interfere with any Symmetrix feature or function No demonstrated performance impact At rest solution means data encrypted only when on drives

Conclusion

This technical note explains the major configuration options and makes recommendations for best practices to support the levels of capacity, consolidation, security, and performance available in the Symmetrix VMAX hardware platform.

The Symmetrix VMAX system provides flexible data protection options to meet different performance, availability, functionality, and economic

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Conclusion


requirements. The ability to support a wide range of service levels with a single storage infrastructure provides a key building block to implementing Information Lifecycle Management (ILM) by deploying a tiered storage strategy.

EMC’s vision is to help customers get the maximum value from their information at the lowest TCO at every point in the information lifecycle. ILM is a way to map the right service level to the right application at the right cost and at the right time.

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Conclusion


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