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Integrating Dell PowerVault™ MD3600i/MD3620i with Existing SANs

A Dell™ Technical White Paper

Dell PowerVault™ Storage Systems

Integrating Dell PowerVaultTM MD3600i/MD3620i Arrays with Existing SANs

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THIS WHITE PAPER IS FOR INFORMATIONAL PURPOSES ONLY, AND MAY CONTAIN TYPOGRAPHICAL

ERRORS AND TECHNICAL INACCURACIES. THE CONTENT IS PROVIDED AS IS, WITHOUT EXPRESS OR

IMPLIED WARRANTIES OF ANY KIND.

Information in this document is subject to change without notice.

© 2011 Dell Inc. All rights reserved.

Reproduction of these materials in any manner whatsoever without the written permission of Dell Inc.

is strictly forbidden.

Trademarks used in this text: Dell™, the DELL™ logo, PowerConnect™, and PowerVault™ are trademarks

of Dell Inc. Microsoft® and Windows® are either trademarks or registered trademarks of Microsoft

Corporation in the United States and/or other countries. Other trademarks and trade names may be

used in this document to refer to either the entities claiming the marks and names or their products.

Dell Inc. disclaims any proprietary interest in trademarks and trade names other than its own.

February 2011


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Contents Introduction ............................................................................................................. 2

Dell PowerVault MD36x0i Product Overview ....................................................................... 3

Primary Features ..................................................................................................... 3

Performance of MD36x0i ............................................................................................ 4

High Performance Tiering Option ................................................................................. 6

Integrating 10GbE MD Series Arrays ................................................................................. 7

The Starting Point – 1GbE PowerVault SAN reference Architecture ........................................ 8

1GbE PowerVault SAN reference Architecture Configuration ................................................ 8

Strategies for Integrating 10GbE Switches ...................................................................... 9

Replacing Existing 1GbE SAN Components ....................................................................... 9

Integrate 10GbE with Existing 1GbE ............................................................................ 10

Preparing the Network Infrastructure .......................................................................... 10

10GbE Switches .................................................................................................... 11

10GbE Cables ....................................................................................................... 11

Mixed Speed SAN Infrastructure .................................................................................... 11

Terminology ........................................................................................................... 11

Recommended Connection Strategies .......................................................................... 12

Attaching a single 10GbE Array to Existing 1GbE Modular Switches ...................................... 12

Adding Dedicated 10GbE Switches to the 1GbE Infrastructure ............................................ 13

What about Blades? ................................................................................................ 13

Conclusion ............................................................................................................. 14


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Introduction

With the PowerVault™ MD36x0i, Dell™ is introducing a new 10GbT Ethernet-based series of iSCSI arrays.

This high performing storage solution represents a next generation advance over 1GbE storage arrays,

with advantages in speed, simplicity, and cost savings However, the introduction of this product

creates questions for administrators on how best to implement the product within their storage

infrastructures. Should they, for example, build out a separate storage area network (SAN) for their 10

gigabit arrays, or should they integrate their new arrays into their existing 1 gigabit PowerVault SAN?

The purpose of this paper is twofold. First, to provide administrators with an overview of the MD36x0i

product and the advantages of 10GbT Ethernet. Second, to provide strategies and best practices for

integrating 10 gigabit Ethernet (10GbE) MD Series arrays into existing one gigabit Ethernet (1GbE) MD

Series PowerVault SANs. While the recommendations described here are not the only possible

architecture options, they are ones that can provide the flexibility to grow the SAN as needed while

continuing to leverage existing server and storage resources, as administrators migrate to newer 10GbE

solutions.

This paper is organized as follows: first, we provide an overview of 10 GbE technology and its

advantages, followed by an overview of the MD36x0i product family, its features and performance. We

then discuss the requirements, recommendations and procedures for introducing 10GbE infrastructure

components into an existing 1GbE networked storage environment consisting of Dell PowerEdge™

Servers with 1GbE host adapters connected to a 1GbE PowerVault Storage Area Network.

Ten Gigabit Ethernet Technology Overview

Ethernet has been around since the mid 1970’s. Over that time, it has been enhanced in speed –

moving from 1Mbps, 10Mbps, 100Mbps, 1Gbps, and now to 10 Gbps – as well as been enriched in terms

of its features and functionality. For example, the most recent version of Ethernet standard has moved

from a broadcast bus architecture to a switched architecture, it has implemented vLANs, jumbo frames

and full-duplex communications as well as many other innovations.

The 10GbT Ethernet standard is not much different from the current implementation of 1GbT Ethernet.

At its core, 10GbE is still based on IEEE 802.3, the main Ethernet standard. The primary differences are

new physical layer implementations and speed. Moreover, 10GbE now supports only full-duplex

communications and does not support half-duplex or shared collision detection implementations.

From a storage networking perspective, it is important to understand that while the 802 standard

states that various physical layer implementations are supported, most initial implementations of

switches, iSCSI targets, and host network controllers, were based on the SFP+ form factor. However,

the industry is moving towards 10GBase-T copper twisted pair as defined in 802.3an-2006 standard.

This physical (PHY) connection provides 10GbT connections over unshielded or shielded twisted pair

cables (CAT6a and above) over distances of up to 100 meters. The advantage of 10GBase-T cable

infrastructure is that it can also be used for 1000Base-T, allowing for a gradual transition from

1000Base-T to 10GBase-T using autonegotiation. The PowerVault MD36x0i supports 10GBase-T

connections.

The 10Gb T Ethernet standard simplifies storage management by reducing the number of ports required

to support a specific level of performance, eliminating the need for link aggregation, reducing the


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number of VLANs, and reducing the need for expensive optical cables. Because of these factors, 10 GbE

provides performance, ease of use, and cost savings advantages over 1 GbE.

Dell PowerVault MD36x0i Product Overview

The PowerVault MD36x0i is the next generation entry-level iSCSI SAN array, replacing the MD3000i array

and adding to the MD32x0i in the product portfolio. The MD36x0i series of arrays provide vastly superior

functionality over the MD3000i and is the industry leader in performance, flexibility, scalability, and

infrastructure simplification.

Primary Features

10GbE Technology: The MD36x0i is the first Dell product to support 10GBase-T ports, with 2 x

10GbT Ethernet ports per controller. 10GbE offers improved performance over 1GbE based arrays, and

with a reduced number of ports needed for the same performance, 10GbE also saves cable and

deployment costs.

Flexibility: When it comes to flexibility, the MD3x0i series is second to none. To best meet specific IT

demands and budgets, users have the following options to choose from:

1. MD3600i single/Dual controller model – Having a single RAID controller in a 2U, 12-drive 3.5” HDD

enclosure provides the lowest cost non-redundant highest storage capacity whereas the dual,

active/active controller model provides high availability and high capacity storage when using large

Near Line SAS Drives.

2. MD3620i single/Dual controller model – Having a single RAID controller in a 2U, 24 drive 2.5” HDD

enclosure provides a non-redundant low cost, high spindle count storage solution that maximizes

IOPS whereas the dual, active/active controller model provides the combination of highly available

storage solution with a high spindle count to maximize IOPS when using Solid State Drives (SSDs) or

15K, 2.5 in SAS drives.

Software: The MD Storage Manager is ideally suited for the full-time storage administrator who wants

complete control over their storage configuration, as well as the part-time system administrator, who

needs an intuitive interface that helps them ensure optimal storage utilization. Various logical and

physical views of the arrays provide at-a-glance storage array settings and status.

Scalability: The MD36x0i series of arrays raises the bar for scalability in the entry-level storage space.

1. Each model is capable of supporting up to 64 physical servers and unlimited virtual servers when

connected to one or more 1GbE or 10GbE switches.

2. They have additional storage capacity of up to a maximum of 96 HDD via the MD1200 and/or

MD1220 enclosures. Users can also mix 3.5” and 2.5” enclosures behind their base units in order to

achieve the optimal drive tiering that best matches an organization’s application and workload

requirements. Within each enclosure users can mix SSD, SAS, and near-line SAS drives maximizing

their return on investment.

Data Protection: The MD36x0i series offers optional data protection features like snapshots and

virtual disk copy services to assist users in protecting their data in a more effective manner.


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Performance of MD36x0i

The MD36x0i series of arrays were designed with performance in mind. Each controller is equipped with

two 10GbT Ethernet ports providing total aggregated theoretical bandwidth of 4000MB/s per array.

In Figure 1, for sequential read applications under base mode (default settings), we can see that

MD36x0i with 4 x 10GbT Ethernet ports performs 4 times better than MD3000i with 4 x 1GbT ports.

Also, MD36x0i performs 1.5 times better than MD32x0i with 8 x 1GbT ports.

Figure 1. Comparison of MD3000i, MD3200i and MD3600i performance for Sequential Reads in Base Mode

For sequential write (Figure 2), random read (Figure 3) and random write (Figure 4) applications, under

base mode (default settings), MD36x0i with 4 x 10GbT Ethernet ports performs almost twice as well as

MD3000i. Also, MD36x0i with only 4 x 10GbT ports performs as well as MD32x0i with 8 x 1GbT ports.

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Figure 2. Comparison of MD3000i, MD3200i and MD3600i performance for Sequential writes in Base Mode

Figure 3. Comparison of MD3000i, MD3200i and MD3600i performance for Random Reads in Base Mode

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Figure 4. Comparison of MD3000i, MD3200i and MD3600i performance for Random Writes in Base Mode

High Performance Tiering Option

High Performance Tier (HPT) is an optional upgrade that can increase the performance of MD3600i and

MD3620i series arrays that have a high drive count, solid state drives (SSDs) or high data transfer

workloads. This implementation is based on an enhanced firmware algorithm and does not require any

new hardware dependencies. Several factors determine the potential performance increase, including

the array configuration, host, operating system, HBA, number and type of drives, and application

workload.

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In Figure 5, for sequential operations, we can see that performance achieved with the high

performance tiering option is approximately 2.5 times the performance achieved in base mode.

Figure 5. Comparison of MD3000i, MD3200i and MD3600i performance for Sequential Reads in HPT Mode

NOTE: Dell PowerVault MD32X0i and MD36X0i storage arrays support active/active controllers, with

each controller being able to simultaneously process I/O. The asymmetric design of the controllers

means that a virtual disk (logical unit number or LUN) is owned by a controller, and all I/O access to

the virtual disk is only possible through the owning controller.

For optimal performance (Base or High Performance Tiering Mode), it is recommended that the users

take advantage of both the controllers for I/O access, distribute virtual disks among the controllers and

modify them to balance I/O access.

For more details about tuning the MD36x0i, please refer to the “ Best Tuning Practices for Dell

PowerVault MD3600i/MD3620i Series Storage Arrays”.

For more details on High Performance Tiering, please refer to the “High Performance Tier

Implementation Guide” white paper.

Integrating 10GbE MD Series Arrays In this section, we look at how to integrate the 10GbE based PowerVault MD3x01 arrays into an existing

PowerVault SAN that consists of arrays using 1 GbE controller technology. We will define a typical 1GbE

PowerVault SAN configuration then look at how to add 10GbE switches, 10GbE PowerVault arrays, and

10GbE hosts to create a mixed 1GbE and 10GbE SAN. In the next section, we will discuss what 10GbE

arrays allow you to do and how to take advantage of the new technology once it is integrated into the

SAN.

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The Starting Point – 1GbE PowerVault SAN reference Architecture

Before talking about the various 10GbE components to be integrated into a 1GbE SAN and the

deployment and management strategies, we have to have a starting point, a typical 1GbE MD Series

SAN. Figure 6 illustrates a typical, fully redundant 1GbE PowerVault SAN reference architecture.

Figure 6. Fully Redundant 1GbE PowerVault SAN Reference Architecture

1GbE PowerVault SAN reference Architecture Configuration

A SAN consists of three major components: hosts, switches, and storage targets. For our 1GbE SAN

starting point, we will make some general assumptions about the configuration of each of these

components, but keep in mind that your configuration may vary. Table 1 describes each SAN

component used and its configuration prior to integrating the 10GbE components.


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Component Configuration

Switches The SAN consists of two 1GbE stackable switches that have 24 or 48 1GbT ports and

at least two 10GbE “uplink” ports. Switches such as the PowerConnect™ 6224,

Cisco® Catalyst® 3750, and others offer this type of configuration at varying costs.

Each switch is configured as follow:

Jumbo Frames have been enabled on all ports

Flow Control has been enabled on all Ethernet ports on the switch to allow

the switch to manage packet flow between servers and arrays.

MD Arrays The SAN consist of two PowerVault MD3000i arrays fully connected using the

following best practices for a redundant, scalable SAN

Connect two ports from each array controller to each switch. This results in 2 ports from one controller (solid orange lines in Figure 6) from each array going to the left-hand switch and 2 ports from the second controller (dashed orange lines in Figure 6) from each array going to the right-hand switch.

Hosts Each host is configured as follows:

Two 1GbT ports dedicated to SAN connectivity. One port from each host

connects to each switch providing a fully redundant path between the host

and the arrays within the SAN.

Microsoft® Windows® operating system with the Microsoft® iSCSI initiator

software installed

Dell’s PowerVault Modular Disk Storage Manager (MDSM) host component is

installed and the MD Series MPIO Device Specific Module (DSM) has been

configured to balance traffic on all host Ethernet ports on the SAN’s IP

subnet.

Table 1. Initial SAN Component Configuration Details

Strategies for Integrating 10GbE Switches

When looking at ways to implement 10GbE based storage technology, there are two basic choices that

are available – replace or integrate. The next two sections look at each of these options a little

differently since this document is really focused on the second option – to integrate 1GbE and 10GbE

technologies.

Replacing Existing 1GbE SAN Components

Replacing the current 1GbE SAN components can present differing challenges depending on the

component being replaced, but the biggest challenge could be in replacing the actual storage arrays

and having to migrate all of the data from the older arrays to newer 10GbE arrays. Regardless, any “rip

and replace” process requires extensive planning and in most cases requires some downtime as

individual components are replaced. PowerVault MD Series arrays have an advantage here.

A core feature of virtual storage – and PowerVault products – is the ability to move volumes from one

storage box to another storage box easily. This feature, along with the ability to have 1GbE arrays in


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the same SAN with 10GbE arrays, means that PowerVault provides a simpler process for migrating to a

10GbE solution than a complete replacement of the entire storage solution that is required with most

vendors. Once the data has been migrated, the 1GbE arrays can be removed from the SAN and

repurposed.

For more details on migrating data to MD36x0i, please refer to the “Data Migration: Moving from the

Dell PowerVaultTMMD3000i/3000 to MD3200i/MD3200i and MD3600i/MD3620i Series Storage Arrays”

white paper.

While this is a viable option, you may want to continue to take advantage of your 1GbE arrays, either

for lower priority data storage, test and development environments, or archival disk-to-disk backup

solutions. The primary way to do this is to take advantage of the same capability just mentioned,

supporting SANs with both 1GbE and 10GbE arrays, to seamlessly integrate 10GbE arrays into the

existing SAN and immediately taking advantage of this higher performance storage in parallel with the

existing storage.

Integrate 10GbE with Existing 1GbE

In many customer environments, there is a need to have 1GbE arrays and 10GbE arrays coexist in the

same PowerVault SAN. There are many advantages to this approach.

1. In many cases, not all applications need the additional performance of a 10GbE array.

2. By integrating 10GbE arrays into the existing 1GbE SAN, the administrator can continue to manage

both types of storage arrays within the same SAN, and he has the flexibility of migrating volumes of

performance hungry applications from existing 1GbE arrays to new, higher-performance 10GbE

arrays.

The next several sections provide more insight into how to integrate 10GbE arrays into your existing

PowerVault SAN.

Preparing the Network Infrastructure

When considering integrating 10GbE networking components into an existing 1GbE SAN infrastructure,

planning is one of the most important steps for success. Several considerations must be made when

planning this integration including:

How many 10GbE arrays need to be integrated?

The number and model of MD arrays helps determine the number of switch ports needed. In case of

MD 36x0i, two 10GbT ports from each array controller for a total of four 10GbT ports per array (2

controllers per array) will need to be connected to the SAN to ensure that all arrays and hosts have

a redundant path through the SAN infrastructure.

How many 10GbE hosts will be connected?

Again, this helps determine the number of switch ports that are needed in the final solution. Each

host requires at least two 10GbE switch ports for high availability.

Do the existing 1GbE switches have or support 10GBASE-T uplink ports?

Each switch vendor has many different models of their 1GbE switches. Each model family will have

different features depending on the target market. A robust, higher performance switch family has

several 10GbT ports that can be used as uplink to other switches or to support 10GbT edge devices

(like a host or array). The number of 10GbT ports available and the socket/cable types supported

varies from vendor to vendor.


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If the existing 1GbE switches do not have integrated 10GbT 10GBASE-T ports, integration of 10GbE

arrays will not be possible without replacing the existing 1GbE switches or without adding 10GbT

10GBASE-T modules within a 1GbE switch.

10GbE Switches

When considering candidate 10GbE switches, it is helpful to understand the options and features that

are typically available in the current offerings. As 10GbE standards progressed and matured, additional

features were added over time by the switch vendors. 10GbE ports, were introduced as uplink ports on

1GbE switches and used a variety of non-standard physical connection types such as XFP, XENPAK, and

X2. They migrated initially to a more standard SFP+ solution and now to a standard 10Gbase-T

connection type for copper connections similar to the 1Gbase-T switches today. The latest 10GbE

switch offering from Dell is PowerConnect 8024, which has 24 10Gbase-T ports.

As an alternative to buying new 10GbE switches such as Dell PowerConnect 8024, Dell also offers

optional expansion 10GbE modules that can replace the stacking modules on existing 1GbE switches,

such as PowerConnect 6224, providing 10GbE capability without the need to buy an entirely new

switch.

10GbE Cables

To carry 10GBASE-T up to distances of 100m, CAT 6A or better twisted pair cables as specified in ISO

11801 amendment 2 or ANSI/TIA-568-C.2 are required.

Mixed Speed SAN Infrastructure The following sections provide insight into mixed speed SAN infrastructures.

Terminology Several different SAN architecture configurations might be considered when integrating 10GbE MD

Series arrays into an existing SAN infrastructure consisting of 1GbE MD Series arrays. The actual

viability of each design depends on the features and capabilities of the candidate switch(s) and may

not be suitable for all switch options.

Note: Each illustration uses the following color scheme to ensure consistency:

Symbol/Color Definition

Indicates 1GbE components, such as cables, NICs, HBAs, or array controllers

Indicates 1GbE MD series arrays

Indicates 10GbE components such as cables, NICs, HBAs, or array controllers

Indicates 10GbE MD series arrays

Indicates hosts connected to SAN

Table 2. Diagram Symbol/Color Scheme


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Recommended Connection Strategies

NOTE: While the following sections talk about active/passive controller configuration, the connections

remain the same for an active/active controller configuration. The difference is that the user has to

configure virtual disks differently to achieve an active/active controller configuration.

Attaching a single 10GbE Array to Existing 1GbE Modular Switches

Using the reference 1GbE MD Series SAN configuration defined earlier, one possible method of

integrating a 10GbE MD array into the existing SAN infrastructure might be to utilize any available

10GbT “uplink” port that might exist on the 1GbE switches. Several vendors integrate 2 or more

10GbTE ports (usually as an optional expansion module) for use as inter-switch links between switches.

If the switch vendor provides 10GBase-T option for these ports, then they could be used to connect to a

10GbE MD 36x0i array as illustrated in Figure 7. Depending on the number of 10GbT ports available and

the internal design of the switch, it might be possible that one 10GbE array could be connected to the

1GbE switch infrastructure using these 10GbT ports.

Using standard PowerVault best practices for connecting an array to the SAN infrastructure in a fully

redundant fashion requires that each port from the active controller be connected to two different

switches and that each port from the standby controller be connected to two different switches (can

be the same two switches as used to connect the active controller). This is illustrated in Figure 7 where

the red solid lines represent the active network connections and the red dashed lines represent the

connections to the standby controller.

Figure 7. Single 10GbE Array Using 10GBase-T Expansion Modules on 1GbE Switches

NOTE: The use of existing 1GbE interconnects limits the storage subsystem maximum performance.

Performance shown in the Performance of MD36x0i section is not applicable.


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Adding Dedicated 10GbE Switches to the 1GbE Infrastructure

If hosts with 10GbE NICs need to be connected to the SAN, it is recommended that dedicated 10GbE

switches be added to the current 1GbE SAN infrastructure. The ability to do this with existing 1GbE

switches depends on these switches having 10GbT uplink ports available to provide inter-switch

connections between the 1GbE and 10GbE switches. Figure 8 illustrates how the 10GbE switches would

leverage any existing 10GbE uplink ports on the 1GbE switches to allow for integration of the 10GbE

SAN infrastructure.

For better performance, it is desirable to isolate the majority of the 10GbE traffic within the 10GbE

designed switches. The only traffic that should traverse the 1GbE-to-10GbE links is traffic between

1GbE hosts and 10GbE arrays as well as any data movement from 1GbE arrays to 10GbE arrays.

Figure 8. Connecting 10GbE switches to existing 1GbE SAN infrastructure (2 x 10GbE switches)

What about Blades?

A blade server solution, such as the PowerEdge M1000e, works similarly to Figure 8. The “host”

switches are the PowerConnect M8024 10 Gigabit Blade IO modules and external PowerConnect 8024

switches would be used for connecting the arrays. In Figure 9, M1000e blade chassis that contain 1GbE

IO modules would connect to existing 1GbE switches and newer M1000e blade chassis that use the

M8024 10GbE IO modules would connect to the external PowerConnect 8024 switches. As in the

previous configuration, this allows the PowerVault SAN to provide storage services to both 1GbE and

10GbE blade server hosts.


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Figure 9. SAN Configuration using M1000e Blade Chassis

Conclusion With the introduction of PowerVault MD36x0i with 10GbT Ethernet ports, Dell has again raised the bar

on performance and scalability that administrators can take advantage of by implementing some

network modifications, such as a true 10GbE end-to-end network.

MD36x0i and 10GbE offer distinct advantages:

1. The performance achieved by 8 x 1GbT ports can be met or beaten with only 4 x 10GbT ports.

2. Because of the reduced number of ports, administrators can save cost on cables, deployment and

management, thus reduce the total cost.

3. 10GBase-T cable infrastructure can also be used for 1000Base-T, allowing for a gradual transition

from 1000Base-T to 10GBase-T. Also, CAT 6a cables are cheaper than SFP+ Cables.

Introducing 10GbE Ethernet into existing SAN infrastructures may not be an obvious choice. It may

seem that it would require administrators to deploy separate network infrastructures, thus creating

more complex deployments, and even more complex storage management strategies, but that is not

necessarily the case. By understanding some basic concepts, 10GbE switches can be integrated

together with 1GbE switches to create a multiple speed SAN allowing the use of both mainstream 1GbE

technology and newer, higher performance 10GbE technology.

Finally, when implementing 10GbE components into your existing 1GbE SAN, it is important to consider

the internal design of the components (host, switches, and targets) of your SAN, as this dictates what

will actually be possible and how the components should be interconnected. This paper has provided

several recommendations on possible approaches. Not all these recommendations work with all

architectures; however the intent is to provide you with an understanding of the concepts and

guidance that should enable a successful SAN design.

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