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NEXSAN HIGH-DENSITY STORAGEBEAST™ and E-Series™

VMware Best Practices Guide

Part Number: P0450150 Rev: A

http://www.nexsan.com/

Copyright © 2010–2018 Nexsan. All Rights Reserved Worldwide. www.nexsan.com

TrademarksNexsan®, BEAST™, Nexsan E60™, Nexsan E60V™, Nexsan E60VT™, Nexsan E60P™, Nexsan E60X™, Nexsan E60XV™ Nexsan E48™,Nexsan E48V™, Nexsan E48P™, Nexsan E48VT™, Nexsan E48X™, Nexsan E48XV™, Nexsan E32V™, Nexsan E32XV™, Nexsan E18™,Nexsan E18V™, Nexsan E18X™, Nexsan E18XV™, and the Nexsan logo are trademarks or registered trademarks of Nexsan.All other trademarks and registered trademarks are the property of their respective owners.

PatentsThis product is protected by one or more of the following patents, and other pending patent applications worldwide:United States patents US8,191,841, US8,120,922United Kingdom patents GB2296798B, GB2297636B, GB2466535B, GB2467622B, GB2467404B

Regulatory complianceUnited States Statement for FCC: This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant toPart 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment isoperated in a commercial environment. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used inaccordance with the instruction manual, may cause harmful interference to radio communications. Operation of this equipment in a residentialarea is likely to cause harmful interference in which case the user will be required to correct the interference at his own expense.Electromagnetic Emissions: FCC Class A, EN 55022 Class A, EN 61000-3-2/-3-3, CISPR 22 Class AElectromagnetic Immunity: EN 55024/CISPR 24, (EN 61000-4-2, EN 61000-4-3, EN 61000-4-4, EN 61000-4-5, EN 61000-4-6, EN 61000-4-8,EN 61000-4-11)Safety: CSA/EN/IEC/UL 60950-1 Compliant, UL or CSA Listed (USA and Canada), CE Marking (Europe)California Best Management Practices Regulations for Perchlorate Materials: This Perchlorate warning applies only to products containing CR(Manganese Dioxide) Lithium coin cells. Perchlorate Material-special handling may apply. Seewww.dtsc.ca.gov/hazardouswaste/perchlorate.

About this documentUnauthorized use, duplication, or modification of this document in whole or in part without the written consent of Nexsan is strictly prohibited.Nexsan reserves the right to make changes to this manual, as well as the equipment and software described in this manual, at any time withoutnotice. This manual may contain links to web sites that were current at the time of publication, but have since been moved or become inactive. Itmay also contain links to sites owned and operated by third parties. Nexsan is not responsible for the content of any such third-party site.

http://www.imation.com/

http://www.dtsc.ca.gov/hazardouswaste/perchlorate

Contents

Contents iii

About this document v

Chapter 1: Recommendations and requirements 9VAAI hardware acceleration 10Recommended Nexsan Storage Systems 11

BEAST with 42 drives 11Nexsan E32V™with 32 drives 11Nexsan E48™/E48V™/E48VT™with 48 drives 11Nexsan E60™/E60V™/E60VT™with 60 drives 11

Recommended settings for Nexsan Storage Systems 12Recommendations for virtual machines 14

Chapter 2: Setting up VMware and Nexsan Storage 15Setting up VMware for use with Nexsan Storage Systems 16Changing queue depth for QLogic and Emulex HBAs 17Setting up Nexsan Storage Systems for use with VMware 18

Path optimization 18Verifying or changingmultipathing 19

Glossary 21

Contents

Nexsan High-Density StorageVMware Best Practices Guide

Nexsanwww.nexsan.com

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iv Part Number: Rev: Bwww.nexsan.com


About this document

This best practices guide provides high-level information and guidance for setting up Nexsan® E-Series™ andBEAST™RAID Storage Systems in a VMware environment using vSphere.NoteWhile Nexsanmakes every effort to ensure the accuracy of technical documentation, screen imagesand procedures may change after publication. In case of discrepancy, please check for the latest updates onthe Nexsan Support Web site. Also, refer to the latest Release Notes for known and resolved issues andworkarounds.

ConventionsHere is a list of text conventions used in this document:

Convention Description

underlinedblue

Cross-references, hyperlinks, URLs, and email addresses.

boldface Text that refers to labels on the physical unit or interactive items in the graphical userinterface (GUI).

monospace Text that is displayed in the command-line interface (CLI) or text that refers to file ordirectory names.

monospacebold

Text strings that must be entered by the user in the command-line interface or in text fieldsin the graphical user interface (GUI).

italics Systemmessages and non-interactive items in the graphical user interface (GUI)References to Software User Guides



v

https://helper.nexsansupport.com/esr_support


Notes, tips, cautions, and warningsNote Notes contain important information, present alternative procedures, or call attention to certain items.Tip Tips contain handy information for end-users, such as other ways to perform an action.

CAUTION: In hardwaremanuals, cautions alert the user to items or situations whichmay causedamage to the unit or result in mild injury to the user, or both. In softwaremanuals, cautions alerts theuser to situations whichmay cause data corruption or data loss.

WARNING: Warnings alert the user to items or situations which may result in severe injuryor death to the user.

Contacting NexsanFor questions about Nexsan products, please visit the Nexsan support Web page, and the E-Series andBEAST Documents and Downloads page. If you are unable to find the answer to your question there, pleasesee our contact information below.

Service and supportNexsan's Technical Services Group provides worldwide assistance with installation, configuration, softwaresupport, warranty, and repair for all Nexsan products. A variety of service and support programs are availableto provide you with the level of coverage and availability your operation requires.

Nexsan Headquarters325 E. Hillcrest Drive, Suite #150ThousandOaks, CA 91360United States of America

Worldwide Web sitewww.nexsan.com

E-Series/BEAST support:https://helper.nexsansupport.com/esr_support

European Head Office, UKUnits 33–35 Parker CentreMansfield RoadDerby, DE21 4SZUnited Kingdom

Contact:https://helper.nexsansupport.com/contact

Related documentsThe following Nexsan product manuals contain related information:

Nexsan High-Density Storage User Guide

Nexsan E-Series™Snapshots and Replication User Guide

NexsanMultipathing Best Practices Guide

Nexsan RAID Storage Plugin for VMware vCenter User Guide

VMware Best Practices Guide

Nexsan E32V™andNexsan E18™/E18V™RAID Storage Units Installation Guide

Nexsan E32V™andNexsan E18™/E18V™RAID Storage Units FRU Removal and Replacement Guide

Nexsan E32XV™andNexsan E18X™/E18XV™RAID Storage Expansion Units Installation Guide

About this document

vi Nexsanwww.nexsan.com

Nexsan High Density StorageVMware Best Practices Guide

https://helper.nexsansupport.com/support

https://helper.nexsansupport.com/esr_downloads.html



https://helper.nexsansupport.com/contact


Nexsan E32XV™andNexsan E18X™/E18XV™RAID Storage Expansion Units FRU Removal andReplacement Guide

Nexsan E60™/E60V™/E60VT™/E60P™andNexsan E48™/E48V™/E48VT™/E48P™RAID StorageUnits Installation Guide

Nexsan E60™/E60V™/E60VT™/E60P™andNexsan E48™/E48V™/E48VT™/E48P™RAID StorageUnits FRU Removal and Replacement Guide

Nexsan E60X™/E60XV™andNexsan E48X™/E48XV™RAID Storage Units Installation Guide

Nexsan E60X™/E60XV™andNexsan E48X™/E48XV™RAID Storage Units FRU Removal andReplacement Guide

About this document



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viii Part Number: Rev: Bwww.nexsan.com


Chapter 1

Chapter 1:Recommendations and requirements

This chapter contains the following sections:

VAAI hardware acceleration 10Recommended Nexsan Storage Systems 11Recommended settings for Nexsan Storage Systems 12Recommendations for virtual machines 14



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VAAI hardware accelerationNexsan E-Series™Storage Systems include a built-in VAAI (vStorage APIs for Array Integration) plugin toprovide hardware acceleration for VMware ESX/ESXi environments. VAAI hardware accelerationfunctionality enables the VMware ESX/ESXi host to offload specific virtual machine and storagemanagementoperations to E-Series Storage Systems. With storage hardware assistance, the VMware ESX/ESXi hostperforms these operations faster and consumes less CPU, memory, and storage fabric bandwidth.E-Series supports these VAAI functions:

Full Copy: This feature enables the storage arrays tomake full copies of data within the array without theneed for the VMware ESXi server to read and write the data. Instead of the server having to read and writeeach block of data, the server sends a single SCSI (Extended Copy) command for a set of contiguousblocks to instruct the storage array to copy the blocks from one location to another. The actual work isperformed on the storage array. This enhancement saves time when cloning a virtual machine, performinga StorageMotion, or deploying virtual machines from a template.

Block Zero: This feature enables storage arrays to zero out a large number of blocks to speed up virtualmachine provisioning. Instead of sendingmultiple redundant write commands over the network, the serveruses the SCSI Write Same command to instruct the storage device to write the same data to a number ofblocks. Instead of having the host wait for the operation to complete, the storage array returns to therequesting service as though the process of writing zeros has been completed. This can be especiallyhelpful when thick-provisioning virtual disks.

Hardware Assisted Locking: This feature provides an alternatemeans of protecting data in VMwarevirtual machine file systems (VMFS). When a host accesses a common data store, only block-level data islocked during access, leaving the rest of the logical unit accessible by other hosts. This also improves thescalability of large ESXi servers sharing a VMFS data store.

► To enable VAAI hardware acceleration:Note VAAI hardware acceleration is enabled by default. Use this procedure only as needed. A reboot isrequired to complete this procedure, so advance preparationmay be required.1. Select System Admin > Cache.

2. EnableSCSI third-party copy extensions.

3. Reboot the Nexsan Storage System.

VAAI hardware acceleration

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Recommended Nexsan Storage SystemsNexsan recommends the following default Nexsan Storage Systems, and array and volume configurations foruse with VMware:Note Nexsan recommends these default configurations because of their versatility. However, youmay getbetter performance using different settings based on your specific environment and I/O characteristics.

BEAST with 42 drivesSuggested array setup:

Four (4) 10-disk RAID 5 arrays

Two (2) pool spares

Create only one (1) volume per array.

Nexsan E32V™with 32 drivesSuggested array setup:

Two (2) 8-disk RAID 5 arrays


Two (2) pool spares


Nexsan E48™/E48V™/E48VT™with 48 drivesSuggested array setup:

One (1) 10-disk RAID 5 array


Two (2) pool spares


Nexsan E60™/E60V™/E60VT™with 60 drivesSuggested array setup:



Two (2) pool spares


Chapter 1: Recommendations and requirements



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Recommended settings for Nexsan Storage SystemsTo use Nexsan Storage Systems in a VMware environment, make sure to review these requirements andrecommendations:

Use vCenter UpdateManager to update all ESX hosts to themost recent version.Note You can alsomanually update the servers by downloading the patches from themy.vmware.comwebsite.

Make sure that all of your host bus adapters (HBAs) are updated to the latest firmware version.

Make sure that the Nexsan Storage System’s SystemMode is All Ports All LUNs (APAL).Figure 1-1: SystemMode page

Recommended settings for Nexsan Storage Systems


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http://my.vmware.com/


(vSphere 4.x systems only)When creating volumes with the NexsanWeb interface, select the Limitvolume size to less than 2TB option. Themaximum LUN size that VMware vSphere 4.x or earlier canrecognize is 2TB.

Figure 1-2: Volume creation page

Note The 2TB limit was increased to 60TB for VAMPS-5 extents in vSphere 6.5.

Label each volumewith a descriptive name.

Map all volumes, starting with LUN 0. Make sure that theUse same LUN for all ports of the same typecheck box is checked.

Figure 1-3: LUN mapping

Give read/write access to all ESX host ports.Figure 1-4: Host port access

Chapter 1: Recommendations and requirements



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Recommendations for virtualmachinesWe recommend these best practices for VMware virtual machines:

Use VMware virtual machine, version 8minimum.

For raw devices and for LUNs larger than 2 TB, use raw devicemapping (RDM).

If you are usingMicrosoft Volume Shadow Copy, use RDM in physical compatibility mode.

Install the VMware Client Tools. For more information on these tools and how to install them, refer to theVMware documentation.

When working with theMicrosoft Windows platform, ensure that you have the latest service pack and allrecommended patches installed.

Thin provisioning is not recommended.

Recommendations for virtual machines


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Chapter 2

Chapter 2:Setting up VMware and Nexsan Storage

This chapter contains the following sections:

Setting up VMware for use with Nexsan Storage Systems 16Changing queue depth for QLogic and Emulex HBAs 17Setting up Nexsan Storage Systems for use with VMware 18Verifying or changingmultipathing 19



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Setting up VMware for use with Nexsan Storage SystemsPerform the following steps to configure the vSphere client for hosting a Nexsan Storage System.

► To prepare vSphere for hosting Nexsan Storage Systems:1. When creating the virtual machines, be sure of the following:

Volumes are configured as datastores.

If you are setting up VMware for failover, set up two datastores.

The storage type is Disk/LUN.

For the connection to the E-Series Storage System, the connection type is VMkernel.

Thin provisioning is NOT used.

All recommendations listed under Recommendations for virtual machines on page 14 are followed.

2. If available, configure Datastore Heartbeating.

3. For host bus adapters (HBAs) and their drivers, do the following:Ensure that all storage HBAs and driver versions are approved for VMware.

Ensure that the driver’s queue depth is set to 16. See Changing queue depth for QLogic and EmulexHBAs on the facing page.As a best practice, QDepth should be set between 8 and 16 to retain some headroom for expansion.In general, the following formula applies to each path between the host machine and the array:[Total number of LUNs] * QDepth < [Array queue depth]Notes:

As queue depth increases, often so does IOPS and latency. You should select a QDepth thatmeets the IOPS and latency requirements of your installation.

The default queue depth value of 32 is usually satisfactory for Emulex HBA cards.

For Fibre Channel HBAs under vSphere 6.5, set the QDepth to its maximum setting.

4. If you expect to have heavy disk I/O loads, youmay want to assign separate storage processors (SPs)to separate systems to handle the amount of traffic bound for storage.

5. To optimize storage array performance, spread I/O loads over the available paths to the storage (that is,across multiple HBAs and storage processors).

6. To help avoid performance problems, make sure that end-to-end Fibre Channel speeds are consistent.

7. For better Sequential and Random Reads performance, use the “Virtual” disk type and either thePVSCSI(Para Virtual SCSI) or LSI Logic Parallel SCSI controller type.

8. When usingmultipathing (recommended), verify that multipathing is correctly implemented. SeeVerifying or changingmultipathing on page 19.

Setting up VMware for use with Nexsan Storage Systems


2


Changing queue depth for QLogic and Emulex HBAsIf you notice unsatisfactory performance of your HBAs, you can change their maximum queue depths. Themaximum value refers to the queue depths reported for various paths to the LUN.Note You only need to set themaximum queue depth when only one virtual machine is active on a LUN.Whenmultiple virtual machines are active on a LUN, the value of Disk.SchedNumReqOutstanding is alsorelevant. In this case, the queue depth value, is equal to whichever value is the lower of the two settings:adapter queue depth orDisk.SchedNumReqOutstanding. In that case, set both adapter queue depth andDisk.SchedNumReqOutstanding to the same lower setting value.

► To change the queue depth for an HBA:1. Determine which HBA module is loaded by running the applicable command in the service console.

If you are using QLogic, run:vmkload_mod -l | grep qla

If you are using Emulex, run:vmkload_mod -l | grep lpfc

2. Run the applicable queue depth command.

If you are using QLogic, run:esxcfg-module -s ql2xmaxqdepth=16 <HBA module>

(where <HBA module> is the result of the previous step)

OR

If you are using Emulex, run:esxcfg-module -s lpfc0_lun_queue_depth=16 <HBA module>

(where <HBA module> is the result of the previous step)Note These example commands set HBA LUN queue depths to 16.

3. Reboot the ESX host.

Chapter 2: Setting up VMware and Nexsan Storage



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Setting up Nexsan Storage Systems for use with VMwarePerform the following steps to configure Nexsan Storage Systems for use with vSphere:

► To prepare the Nexsan Storage Systems:1. When setting up RAID arrays and volumes, follow the recommendations for the Storage System you are

configuring, which are listed in Recommended Nexsan Storage Systems on page 11 and Recommendedsettings for Nexsan Storage Systems on page 12.

2. Wherever possible, update your Nexsan Storage System to the latest available firmware. Please seeService and support on page vi.

3. (E-Series units only) If you wish to implement VAAI (see VAAI hardware acceleration on page 10), youmust have firmware version Q011.1101 or later. See "Update Firmware" in Chapter 2 of theNexsanHigh-Density Storage User Guide.

4. For iSCSI connections, use Jumbo Frames wherever possible. See "Configure 10Ge iSCSI" and"Configure 1Ge iSCSI" in Chapter 3 of theNexsan High-Density Storage User Guide.

5. Install the Nexsan RAID Storage plugin for VMware vCenter. See the installation guide on NexsanSupport page for E-Series.

Path optimizationNexsan Storage Systems support all modes of VMwaremultipathing.

► To optimize load balancing:1. Run the system at full production level for several days to fill the performance logs.

2. Use the Nexsan performance page to analyze the host port and disk usage.a. Open the unit’s performance data page by going to

<unit.IP.address>/admin/perfdata.asp.

b. Examine the hosts’ read and write throughput, noting especially the hosts that have abnormally highor low throughput.

c. Examine the arrays’ data loads, noting especially the arrays that have abnormally high or low load.

3. Adjust array load by moving VMs to less-used datastores.

4. Adjust port load by changing the primary fixed path in ESX Pathmanagement.

This applies to both iSCSI and Fibre Channel connections.

Setting up Nexsan Storage Systems for use with VMware


2




Verifying or changingmultipathingUse this process to identify the storage system and to verify that the volume or array is owned by thecontroller orWWN (WorldWide Name) that vSphere has selected as the I/O path.Nexsan Storage Systems support all modes of VMwaremultipathing.

► To verify or change multipathing:1. On the VMware vSphere Client Shortcuts page (HTML5 client, shown) orHome page (Flash Client),

select theNexsan Storage icon.

2. In the Viewing pane, select Connectivity and Multipathing.

3. Click aHost icon as shown.

Chapter 2: Setting up VMware and Nexsan Storage



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4. In the Connectivity andMultipathing pane, you can:a. Mount and unmount host servers,

b. View multipathing Policies and Paths, and

c. Open the Edit Multipathing window if you need to change the Path selection policy.

► To edit multipathing:5. In theEdit Multipathingwindow, you can

Change thePath selection policy for selected or multiple runtimes.

Verifying or changingmultipathing


2


Glossary

110Gb Ethernet

A 10 gigabit per second (Gb/s) Ethernet connection using either fiber-optic cables or twisted-pair copperwires.

10Gb iSCSIAn iSCSI connection that runs on a 10Gb Ethernet network.

10GbESee “10Gb Ethernet” and “10Gb iSCSI”.

AActive Directory

Microsoft’s directory service, used by all supportedWindows operating systems. Abbreviated “AD”.

All Ports All LUNs (APAL)modeA systemmode for Nexsan storage systems. In this mode, the entire system operates as a single node.The volumes can bemapped to any or all ports on both RAID controllers. When a controller fails, theports on that controller become inaccessible. However, if the volumes aremapped to ports on the othercontroller as well (which requires the host to be configured for multipathing), they remain accessible tothe host, which sees the storage become active through its second path.

arrayIn Nexsan storage terms, an array is a linked group of one or more physical, independent hard diskdrives. In VMware, a storage pool is equivalent to an array. See also “RAID”.



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Glossary

22 Nexsanwww.nexsan.com


Bbit

The smallest unit of digital data, representing a 0or a 1. Abbreviated “b”.

boot driveThe device from which a computer’s operatingsystem is loaded. Typically, an internal harddisk drive (or one of several partitions on such adrive) is used for this purpose, but any attachedstorage device—such as an optical disc drive, aUSB flash drive, or other attached storage—canbe used.

byteA unit of data that is 8 bits long. Often used foralphanumeric characters. Abbreviated “B”.

CController

See RAID Controller

DDatastore

In VMware, datastores are virtual containerssimilar to file systems, designed to containstorage devices. Datastores contain structuresused to store virtual machines and hiddendetails about each storage device. Datastorescan also store VM templates, ISO images, andfloppy images. See https://pubs.vmware.com

DNSSee “Domain Name System”.

Domain Name SystemA program or computer server that implements aname-service protocol. It maps a human-recognizable identifier to a system-internal,often numeric, identification or addressingcomponent (usually an IP address).

EE-Series

The series of Nexsan units that includes theNexsan E18, E48, and E60 storage units (andtheir V and VT variants), the Nexsan E32V, theNexsan E18X, E48X, and E60X expansion units(and their XV variants), and the Nexsan E32XV.Nexsan E-Series units feature Active DrawerTechnology, Anti-Vibration Design, andCoolDrive Technology.

EthernetA system for connecting a number of computersystems to form a local area network (LAN),with protocols to control the passing ofinformation and to avoid simultaneoustransmission by two or more systems. Supportsdata transfer rates of 10, 100, 1,000, and 10,000megabits per second (Mb/s). 10, 100, and1,000Mb/s networks are often referred to as10BASE-T, 100BASE-T, and 1000BASE-T,respectively. 10,000Mb/s networks are usuallyreferred to as 10Gb Ethernet or 10GbE.

Ffailover

The capability of a system to switch overautomatically to a redundant or standby systemupon the failure or abnormal termination of thepreviously active system. In Nexsan storagesystems, failover describes one RAID controllertaking over the host connections and RAID setcontrol of the other RAID Controller when thatcontroller fails.

Fibre ChannelA gigabit (Gb) speed network technologyprimarily used for storage networking and thecurrent standard connection type for storagearea networks (SANs). Despite its name, FibreChannel signaling can run on both twisted-paircopper wire and fibre-optic cables.


Glossary



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Fibre Channel portAny entity that actively communicates over aFibre Channel network. Usually implemented ina device such as disk storage or a FibreChannel switch. Depending on the system, theFibre Channel ports on Nexsan StorageExpansions can support 2Gb/s, 4Gb/s, or 8Gb/sconnections.

Fibre Channel switchA network switch compatible with the FibreChannel protocol. Allows the creation of a FibreChannel network, which is currently the corecomponent of most storage area networks(SANs).

firmwareSmall, fixed software applications, stored inread-only memory (ROM) or programmableread-only memory (PROM), that internallycontrol various electronic devices. In Nexsan E-Series, and SATABeast/SASBeast storagesystems, each RAID controller is loaded withfirmware to control its functionality.Occasionally, this firmwaremust be updatedusing the Update Firmware page in the graphicaluser interface.

frameA data packet on an Ethernet or Fiber Channellink. Each frame encapsulates a piece of datawith sender and destination information, alongwith a data integrity check routine. Normalframes can contain data up to 1,500 bytes inlength. Jumbo frames can contain larger datapayloads (9,000 bytes on Nexsan storagesystems) and are supported on 1Gb/s and10Gb/s Ethernet (10GbE) networks. Jumboframes are typically used to boost performanceof iSCSI traffic.

GGB

Gigabyte. Approximately one billion(1,000,000,000) bytes. Used to describe thestorage capacity of hard disk drives. A gigabyte

is usually computed as 10^9 (1,000,000,000)bytes, but can also be computed as 2^30(1,073,741,824) bytes (often called a “binarygigabyte” and abbreviated GiB).

GB/sGigabytes (GB) per second. Used to describethe speed of network data transmission. 1 GB/sis eight times faster than 1Gb/s.

GiBA binary gigabyte, computed as 2^30(1,073,741,824) bytes. See “GB”.

gigabit interface converterA standard for transceivers, commonly usedwith Gigabit (Gb) Ethernet and Fiber Channel,with a hot-swappable electrical interface.Gigabit interface converter ports can support awide range of physical media, from copper tooptical fiber, at lengths of up to hundreds ofkilometers.

graphical user interfaceA type of user interface that allows users tointeract with electronic devices using imagesrather than text commands. Nexsan storageunits use a graphical user interface for systemconfiguration.

GUISee “graphical user interface”.

Hhost

A physical computer, server, or other devicewhich accesses the volumes in a NexsanStorage System. The host can be connected tothe Nexsan Storage System with a FibreChannel connection, an iSCSI connection, or aSAS connection. A VMware host computer runsvirtual machines.

hot spareA spare disk in a RAID array designated as "hotstandby", available to replace a failed diskwithout requiring a system shutdown.


Glossary



HTTPS(HTTP Secure) Communications protocol forsecure communication over a computernetwork, with especially wide deployment onthe Internet. Technically, it is not a protocol initself; rather, it is the result of simply layering theHypertext Transfer Protocol (HTTP) on top ofthe SSL/TLS protocol, thus adding the securitycapabilities of SSL/TLS to standard HTTPcommunications.

II/O

Input/Output. The communication between aninformation processing system (such as acomputer or a Nexsan storage system’sRAID controller), and the outside world (eitheran operator or another information processingsystem). Inputs are the signals or data receivedby the system, and outputs are the signals ordata sent from it.

IP addressInternet Protocol address. A numerical labelassigned to each device (such as a computer,printer, or Nexsan storage unit) on a computernetwork that uses TCP/IP for communication.

IP Configuration ToolOne of six Nexsan Storage Tools. Allows usersto configure the IP address of a Nexsan storagesystem on the local subnet.

iSCSIInternet Small Computer System Interface. Atransport protocol that provides for the SCSIprotocol to be carried over a TCP/IP network.

iSCSI initiatorIn storage networks, initiators are typicallysoftware or hardware Fibre Channel, iSCSI, orSAS adapters accessing information on diskstorage systems, the targets.

Jjumbo frame

See “frame”.

KKB

Kilobyte. Approximately one thousand (1,000)bytes. Used to describe the storage capacity ofhard disk drives and the stripe size in RAIDs. Akilobyte is usually computed as 10^3 (1,000)bytes, but can also be computed as 2^10 (1,024)bytes (often called a “binary kilobyte” andabbreviated KiB).

KbitKilobit. Approximately one thousand (1,000)bits.

KiBA binary kilobyte. Computer as 2^10 (1,024)bytes. See “KB”.

Lload balance policy

In multipathing, a set of instructions for themultipathing software to follow in order to ensurethat I/O transfers through host paths areoptimally routed and that no one path getsoverloaded with data.

logical unitSee “volume”.

LUNLogical Unit Number. An identification schemefor storage disks that supports a small numberof logical units. On Nexsan storage systems,LUNs are assigned to volumes and areaddressed as LUN 0 through 254.


Glossary



25

MMB

Megabyte. Approximately onemillion(1,000,000) bytes. Used to describe the storagecapacity of hard disk drives. A megabyte isusually computed as 10^6 (1,000,000) bytes,but can also be computed as 2^20 (1,048,576)bytes (often called a “binary megabyte” andabbreviatedMiB).

MB/sMegabytes (MByte) per second. Used todescribe the speed of network datatransmission. 1MB/s is eight times faster than1Mb/s.

MbitMegabit. Approximately onemillion (1,000,000)bits.

Mbit/sMegabits (Mb) per second. Used to describe thespeed of network data transmission.

MiBA binary megabyte. Computed as 2^20(1,048,576) bytes. SeeMByte.

multipathingA means of presenting volumes to a particularhost or hosts via redundant data paths. Theintent is to maintain I/O in the event of a pathfailure. Multipathingmay also be used toincrease performance. If not configuredproperly, multipathingmay lead to datacorruption, as an operating systemmay notinherently realize that the redundant paths are ofthe same volume and thus could treat them asdifferent volumes.

PPSC

Platform Services Controller (PSC) "is acomponent of the VMware Cloud Infrastructure

Suite. PSC deals with identity management foradministrators and applications that interactwith the vSphere platform." Seehttp://docs.vmware.com

RRAID

Redundant Array of Independent Disks. Asystem usingmultiple hard drives organized intoa single logical unit for the sharing or replicationof data in order to increase data integrity, fault-tolerance, and throughput. Also referred to as aRAID set. RAIDs are organized intoRAID levels, which describe their architectureand configuration.

RAID ControllerA hardware device, software program, orcombination of the two whichmanages thephysical disk drives in a RAID and presentsthem as a single logical unit to attacheddevices. The RAID Controllers in Nexsanstorage units are hardwaremodules. NexsanRAID Controllers also provide connections forsystem administration and configuration.

RDMRDM is "amapping file in a separate VMFSvolume that acts as a proxy for a raw physicalstorage device. The RDM allows a virtualmachine to directly access and use the storagedevice. The RDM contains metadata formanaging and redirecting disk access to thephysical device." See About Raw DEviceMapping, in http://docs.vmware.com

rebootTo restart a computer or computerizedelectronic device. See also system reboot.

SSAS

Serial Attached SCSI. A serial version of theSCSI interface. A point-to-point architecture that


Glossary



uses a disk controller with four or more channelsthat operate simultaneously. Each full-duplexchannel, known as a SAS port, transfers data at1.5Gb/s, 3Gb/s, or 6Gb/s in each direction. SASalso supports Serial ATA (SATA) drives, whichcan bemixed with SAS drives in a variety ofconfigurations.

SATASerial Advanced Technology Attachment. Aconnection standard for fixed and removablehard disk drives.

SCSISmall Computer System Interface. A collectionof standards and proposed standards forinput/output (I/O) communication, primarilyintended for connecting storage subsystems ordevices to hosts.

Storage PoolSee "Array"

TTB

Terabyte. Approximately one trillion(1,000,000,000,000) bytes. Used to describe thestorage capacity of hard disk drives. A terabyteis usually computed as 10^12(1,000,000,000,000) bytes, but can also becomputed as 2^40 (1,099,511,627,776) bytes(often called a “binary terabyte” and abbreviatedTiB).

TiBA binary terabyte. Computed as 2^40(1,099,511,627,776) bytes. See TB.

VVAAI

vStorage APIs for Array Integration is a pluginthat provides hardware acceleration in VMwareESX/ESXi environments.

vCSAThe vCenter Server Appliance is apreconfigured Linux virtual machine, which isoptimized for running VMware vCenter Server®and the associated services on Linux. Seehttp://docs.vmware.com

VMFSVirtual machine file system, a clustered filesystem used by VMware vSphere to storevirtual machine disk images and snapshots.

volumeAn area of usable storage that is addressed as asingle unit as if it were a separate, physical diskdrive. Volumes can exist on a single disk driveor on a RAID that spans multiple disk drives.

WWWN

AWorldWide Name (WWN) "orWorldWideIdentifier (WWID) is a unique identifier used instorage technologies including Fibre Channel,Advanced Technology Attachment (ATA) orSerial Attached SCSI (SAS)." Seehttp://www.wikipedia.org


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Nexsan® and the Nexsan logo are trademarksor registered trademarksofNexsan.

All other trademarksand registered trademarksare the property of theirrespective owners.

This product is protected byone or more of the following patents, and otherpending patent applicationsworldwide: United StatespatentsUS8,191,841,US8,120,922; United Kingdom patentsGB2466535B, GB2467622B,GB2467404B, GB2296798B, GB2297636B

Part Number: Rev: B



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