NEXSAN HIGH-DENSITY
STORAGE
BEAST™ and E-Series™
VMware
Best Practices Guide
Part Number: P0450150 Rev: A
NEXSAN | 910 E Hamilton Ave, Campbell, CA 95008| p. 1.760.690.1111 | www.nexsan.com
Copyright © 2010–2016 Nexsan. All Rights Reserved Worldwide. www.nexsan.com
Trademarks
Nexsan®, 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.
Patents
This product is protected by one or more of the following patents, and other pending patent applications worldwide:
United States patents US8,191,841, US8,120,922
United Kingdom patents GB2296798B, GB2297636B, GB2466535B, GB2467622B, GB2467404B
Regulatory compliance
United States Statement for FCC: This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to
Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is
operated in a commercial environment. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in
accordance with the instruction manual, may cause harmful interference to radio communications. Operation of this equipment in a residential
area 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 A
Electromagnetic 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. See
www.dtsc.ca.gov/hazardouswaste/perchlorate.
About this document
Unauthorized 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 without
notice. This manual may contain links to web sites that were current at the time of publication, but have since been moved or become inactive. It
may also contain links to sites owned and operated by third parties. Nexsan is not responsible for the content of any such third-party site.
Contents
Contents
About this manual
Audience
Conventions
Text
Notes, tips, cautions, and warnings
Contacting Nexsan
Contacting service and support
Related documents
iv
iv
iv
iv
iv
v
v
vi
Safety notices
vii
Revision history
viii
Chapter 1: Recommendations and requirements
VAAI overview
Recommendations for specific Nexsan units
BEAST with 42 drives
E18/E18V with 18 drives
E32V with 32 drives
E48/E48V/E48VT with 48 drives
E60/E60V/E60VT with 60 drives
Recommendations for all Nexsan units
Recommendations for virtual machines
1
2
3
3
3
3
3
3
5
7
Chapter 2: Set Up VMware and Storage Units
8
Set up VMware for use with Nexsan storage units
Changing queue depth for QLogic and Emulex HBAs
Verifying multipathing
Set up storage units for use with VMware
Path optimization
9
10
11
15
15
Glossary
Nexsan High-Density Storage
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About this manual
About this manual
This best practices guide provides high-level information and guidance for setting up Nexsan® E-Series™ and
BEAST™ RAID storage units in a VMware environment using vSphere.
Audience
This guide has been prepared for the following audience:
IT system administrators
Engineers
Technicians
Conventions
Text
Internal cross-references, hyperlinks, URLs, and email addresses are displayed in underlined blue.
Cross-references to other documents, system messages, and non-interactive items in the graphical user
interface (GUI) are displayed in italic.
Text that refers to labels on the physical unit or interactive items in the graphical user interface (GUI) is in
boldface.
Notes, tips, cautions, and warnings
Note 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 hardware manuals, cautions alert the user to items or situations which may cause
damage to the unit or result in mild injury to the user, or both. In software manuals, cautions alerts the
user to situations which may cause data corruption or data loss.
WARNING: Warnings alert the user to items or situations which may result in severe injury
or death to the user.
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About this manual
Contacting Nexsan
Nexsan Headquarters
910 E Hamilton Ave,
Campbell, CA 95008
UNITED STATES
Telephone
866-2-NEXSAN (1.866.263.9726)
Worldwide
1.760.690.1111
Contacting service and support
Nexsan's Technical Services Group provides worldwide assistance with installation, configuration, software
support, warranty and repair for all Nexsan products. A variety of service and support programs are available
to provide you with the level of coverage and availability your operation requires.
US and Canada
Toll-free
866.263.9726
Outside of North America
760.690.1111
E-mail
[email protected]
Europe, Middle East, Africa
By phone
+44 (0) 1332 291600
E-mail
[email protected]
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About this manual
Related documents
The following Nexsan product manuals contain related information:
NexsanHigh-Density Storage User Guide
Nexsan E-Series™ Snapshots and Replication User Guide
Nexsan Multipathing Best Practices Guide
Nexsan E32V™ and Nexsan E18™/E18V™ RAID Storage Units Installation Guide
Nexsan E32V™ and Nexsan E18™/E18V™ RAID Storage Units FRU Removal and Replacement Guide
Nexsan E32XV™ and Nexsan E18X™/E18XV™ RAID Storage Expansion Units Installation Guide
Nexsan E32XV™ and Nexsan E18X™/E18XV™ RAID Storage Expansion Units FRU Removal and
Replacement Guide
Nexsan E60™/E60V™/E60VT™/E60P™ and Nexsan E48™/E48V™/E48VT™/E48P™ RAID Storage
Units Installation Guide
Nexsan E60™/E60V™/E60VT™/E60P™ and Nexsan E48™/E48V™/E48VT™/E48P™ RAID Storage
Units FRU Removal and Replacement Guide
Nexsan E60X™/E60XV™ and Nexsan E48X™/E48XV™ RAID Storage Units Installation Guide
Nexsan E60X™/E60XV™ and Nexsan E48X™/E48XV™ RAID Storage Units FRU Removal and
Replacement Guide
SATABeast/SASBeast Installation and Maintenance Manual
SATABoy/SASBoy Installation and Maintenance Manual
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Safety notices
Safety notices
Always observe the following precautions to reduce the risk of injury and equipment damage:
Computer components and disk drives are sensitive to static discharge. Take precautions to discharge
any electrostatic charge from your person before and while handling components with your hands or any
tools. Use an anti-static wrist-strap.
Ensure correct lifting methods are used when removing the unit from its packaging and positioning it into its
required location. When lifting the system, two people at either end should lift slowly with their feet spread
out to distribute the weight. Always keep your back straight and lift with your legs.
When removing the unit from the packaging, DO NOT lift the unit by any plastic parts or module handles on
the chassis. Doing so may cause damage to the chassis or to internal components, or both. Lift the unit
ONLY by the bottom edges of the chassis, using safe lifting practices.
Do not install the unit in an enclosed cabinet or other small area without ventilation.
When installing the unit as a rack-mounted component, ensure that all Nexsan-supplied mounting fixtures
are secure. All bolts and screws should be fully tightened. Failure to comply with this may result in the unit
not being fully supported in the rack and could lead to the product falling from the rack, causing personal
injury or damage to other rack components.
Ensure that the rack is sufficiently stable by having wall anchors and/or stabilizing legs, and that the floor
supporting the rack has sufficient strength for the overall weight loading.
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Revision history
Revision history
This section lists updates and new material added to Nexsan VMware Best Practices Guide.
NXS-ESVM-BP, Rev. 01, August 2014
Rordered and reorganized all information in the Nexsan VMware Best Practices Guide; removed Disk
Optimization section; added section Recommendations for virtual machines on page 7; expanded on
information in section Set up VMware for use with Nexsan storage units on page 9; added section To prepare
the Nexsan RAID storage unit: on page 15.
Old format
Version 2.5, September 2012
Expanded upon information for general setup of all Nexsan RAID storage units and settings for specific
Nexsan RAID storage units; added instructions for using the Nexsan performance document to analyze host
port and disk usage; removed section Poor performance and high disk latency with some storage
configurations; added section Verifying Multipathing; added section Additional Recommendations for vSphere
5.0; added section VAAI Support.
Version 2.1, August 2011
Condensed information about setup of Nexsan RAID storage units; added section Poor performance and high
disk latency with some storage configurations.
Version 2.0, July 2011
Updated document with new screenshots and corporate colors; added section E18 with 18 Drives; added
section E60 with 60 Drives.
Version 1.0
First release of the Nexsan VMware Best Practices Guide.
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Chapter
1
Chapter
Recommendations
1:
and requirements
This chapter contains the following sections:
VAAI overview
2
Recommendations for specific Nexsan units
3
Recommendations for all Nexsan units
5
Recommendations for virtual machines
7
VAAI overview
VAAI overview
Nexsan E-Series™ RAID storage units include a built-in VAAI (vStorage APIs for Array Integration) plugin to
provide hardware acceleration on the E-Series unit when integrated into a VMware ESX/ESXi environment.
VAAI hardware acceleration functionality enables the VMware ESX/ESXi host to offload specific virtual
machine and storage management operations to the E-Series unit. With storage hardware assistance, the
VMware ESX/ESXi host performs these operations faster and consumes less CPU, memory, and storage
fabric bandwidth.
E-Series units support these four VAAI functions:
Full Copy: This feature enables the storage arrays to make full copies of data within the array without the
need for the VMware ESXi server to read and write the data. Instead of the server having to read and write
each block of data, the server sends a single SCSI (Extended Copy) command for a set of contiguous
blocks to instruct the storage array to copy the blocks from one location to another. The command across
the network is small, and the actual work is performed on the storage array. This can be especially helpful
when cloning a virtual machine, performing a Storage Motion, 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 virtual
machine provisioning. Instead of sending multiple redundant write commands over the network, the server
uses the SCSI Write Same command to instruct the storage device to write the same data to a number of
blocks. Instead of having the host wait for the operation to complete, the storage array returns to the
requesting service as though the process of writing zeros has been completed. This can be especially
helpful when thick-provisioning virtual disks.
Hardware Assisted Locking: This feature provides an alternate means of protecting data in VMFS
cluster file system environments. When a host accesses a common datastore, instead of having to lock
and entire logical unit (which prevents any other hosts from accessing), the host has the ability to lock only
the data it is accessing at the block level, leaving the rest of the logical unit accessible by other hosts. This
also improves the scalability of large ESXi servers sharing a VMFS datastore.
These features are enabled by checking the SCSI third-party copy extensions check box on the System
Admin > Configure Cache page of the E-Series graphical user interface.
Notes: It is not recommended that this setting be changed on a live system.
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Chapter 1: Recommendations and requirements
Recommendations for specific Nexsan units
The following default array and volume configurations are recommended:
Note Nexsan recommends the default configurations because of their versatility. However, you may get
better performance using different settings based on your specific environment and I/O characteristics.
Note The [[[Undefined variable E-Series Variables.Boy]]] is not certified for use with VMware/vSphere
environments.
BEAST with 42 drives
Suggested array setup:
Four (4) 10-disk RAID 5 arrays
Two (2) pool spares
Create only one (1) volume per array.
E18/E18V with 18 drives
Suggested array setup:
One (1) 9-disk RAID 5 array
One (1) 8-disk RAID 5 array
One (1) pool spare
Create only one (1) volume per array.
E32V with 32 drives
Suggested array setup:
Two (2) 8-disk RAID 5 arrays
Two (2) 7-disk RAID 5 arrays
Two (2) pool spares
Create only one (1) volume per array.
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E48/E48V/E48VT with 48 drives
Suggested array setup:
One (1) 10-disk RAID 5 array
Four (4) 9-disk RAID 5 arrays
Two (2) pool spares
Create only one (1) volume per array.
E60/E60V/E60VT with 60 drives
Suggested array setup:
Four (4) 10-disk RAID 5 arrays
Two (2) 9-disk RAID 5 arrays
Two (2) pool spares
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Recommendations for specific Nexsan units
Create only one (1) volume per array.
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Chapter 1: Recommendations and requirements
Recommendations for all Nexsan units
To use Nexsan RAID storage systems in a VMware environment, make sure to review these requirements
and recommendations:
Use vCenter Update Manager to update all ESX hosts to the most recent version.
Note You can also manually update the servers by downloading the patches from the MyVMware.com
website.
Make sure that all of your host bus adapters (HBAs) are updated with the newest firmware version.
Make sure that the Nexsan unit’s System Mode is All Ports All LUNs (APAL).
Figure 1-1: System Mode page
(vSphere 4.x or earlier only) When creating volumes in the Nexsan GUI, select the Limit volume size to
less than 2TB option. The maximum LUN size that VMware vSphere 4.x or earlier can recognize is 2TB.
Figure 1-2: Volume creation page
1
Note The 2TB limit was increased to 60TB for VMFS-5 extents in vSphere 5.0.
Label each volume with a descriptive name.
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Recommendations for all Nexsan units
Map all volumes, starting with LUN 0. Make sure that the Use same LUN for all ports of the same type
check box is checked.
Figure 1-3: LUN mapping
Give read/write access to all ESX host ports.
Figure 1-4: Host port access
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Chapter 1: Recommendations and requirements
Recommendations for virtual machines
We recommend these best practices for VMware virtual machines:
Use VMware virtual machine version 8, minimum.
For raw devices and for LUNs with more than 2 TB, use raw device mapping (RDM).
If you are using Microsoft 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 the
VMware documentation.
When working with the Microsoft Windows platform, ensure that you have the latest service pack and all
recommended patches installed.
Thin provisioning is not recommended.
For more information about configuration maximums for vSphere 5.0, 5.1, and 5.5, please refer to the
following VMware documentation:
http://www.vmware.com/pdf/vsphere5/r50/vsphere-50-configuration-maximums.pdf
http://www.vmware.com/pdf/vsphere5/r51/vsphere-51-configuration-maximums.pdf
http://www.vmware.com/pdf/vsphere5/r55/vsphere-55-configuration-maximums.pdf
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Chapter
2
Chapter
Set Up
2: VMware and Storage Units
This chapter contains the following sections:
Set up VMware for use with Nexsan storage units
Set up storage units for use with VMware
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Set up VMware for use with Nexsan storage units
Set up VMware for use with Nexsan storage units
Perform the following steps to configure the vSphere client for hosting a Nexsan RAID storage unit.
► To prepare vSphere for hosting Nexsan RAID storage:
1. When creating the virtual machines, be sure of the following:
Volumes are configured as datastores.
If you are setting up VMware for failover, two datastores are in use.
The storage type is Disk/LUN.
For the connection to the E-Series unit, the connection type is VMkernel.
Thin provisioning is NOT used.
All recommendations listed under Recommendations for virtual machines on page 7 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 Emulex
HBAs on the facing page for specific information regarding QLogic and Emulex HBAs.
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 that
meets 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 5.0, set the QDepth to its maximum setting.
4. If you expect to have heavy disk I/O loads, you may want to assign separate storage processors (SPs)
to separate systems to handle the amount of traffic bound for storage.
2
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. Make sure that end-to-end Fibre Channel speeds are consistent to help avoid performance problems.
7. It has been observed that using the “Virtual” disk type and either the “PVSCSI (Para Virtual SCSI)” or
“LSI Logic Parallel” SCSI controller type yielded better performance numbers for Sequential and Random
Reads.
8. When using multipathing (recommended), verify that multipathing is correctly implemented. See
Verifying multipathing on page 11.
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Chapter 2: Set Up VMware and Storage Units
Changing queue depth for QLogic and Emulex HBAs
If you notice unsatisfactory performance of your HBAs, you can change their maximum queue depths. The
maximum value refers to the queue depths reported for various paths to the LUN.
You only need to set the maximum queue depth when one virtual machine is active on a LUN. When multiple
virtual machines are active on a LUN, the value of Disk.SchedNumReqOutstanding is also relevant. The
queue depth value, in this case, is equal to whichever value is the lower of the two settings: adapter queue
depth or Disk.SchedNumReqOutstanding. The recommendation is to set both
Disk.SchedNumReqOutstanding and the adapter queue depth to the same value.
► To change the queue depth for an HBA:
1. Determine which HBA module is loaded by using the following commands in the service console:
QLogic: vmkload_mod -l | grep qla
Emulex: vmkload_mod -l | grep lpfc
2. Run one of the following commands:
QLogic: esxcfg-module -s ql2xmaxqdepth=16 <HBA module> (where <HBA module> is the
result of the previous step)
Emulex: esxcfg-module -s lpfc0_lun_queue_depth=16 <HBA module> (where
<HBA module> is the result of the previous step)
Note In these examples, the HBAs will have their LUN queue depths set to 16.
3. Reboot the ESX host.
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Set up VMware for use with Nexsan storage units
Verifying multipathing
Use this process to identify the storage system and to verify that the volume/array is owned by the
controller/WWN that vSphere has picked as the I/O path.
Figure 2-1: vSphere Client, storage adapter configuration screen
2
► To verify multipathing:
1. In the vSphere Client, select the appropriate ESX host or cluster in the list.
2. Click the Configuration tab.
3. Click the Storage Adapters link.
4. Select one of the HBA ports (Fibre Channel or iSCSI) to display its information in the Details section.
5. Make sure that the View is set to Devices.
6. Right-click the listed device and select Manage Paths.
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Chapter 2: Set Up VMware and Storage Units
7. Do one of the following:
For Fibre Channel networks:
Figure 2-2: Manage Paths dialog for Fibre Channel
a. In the Status column, find the path that is listed as Active (I/O).
b. In the Target column, look at the pair of numbers fifth from the end:
If this number is 20 through 23, the path is to Controller 0.
If this number is 24 through 27, the path is to Controller 1.
c. In the Target column, note the last four digits.
d. In the LUN column, note the LUN number.
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Set up VMware for use with Nexsan storage units
For iSCSI networks:
Figure 2-3: Manage Paths dialog for iSCSI
a. In the Status column, find the path that is listed as Active (I/O).
b. In the Target column, look at the number after the p near the middle of the iqn.
If this number is 0, 1, 2, or 3, the path is to Controller 0.
If this number is 4, 5, 6, or 7, the path is to Controller 1.
c. In the Target column, note the four digits that immediately preceed the IP address.
d. In the LUN column, note the LUN number.
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8. Launch the Nexsan IP Configuration Tool.
Figure 2-4: Nexsan IP Configuration Tool
9. In the System ID column, find the system ID with the last four digits matching those of the Target in the
Manage Paths dialog . The unit with that system ID is the unit that the path goes to.
10. Open a browser and navigate to the unit by its IP address.
11. Select RAID Information > Volumes to go to the Configured Logical Volumes page.
Figure 2-5: Configured Logical Volumes page in the E-Series unit GUI
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12. Find the LUN number in the Fibre or iSCSI column and verify that the array to which the volume belongs
is assigned to the controller you identified earl;ier.
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Set up storage units for use with VMware
Set up storage units for use with VMware
Perform the following steps to configure the Nexsan RAID storage unit for use with vSphere:
► To prepare the Nexsan RAID storage unit:
1. When setting up RAID arrays and volumes, follow the recommendations for the unit you are configuring,
which are listed in Recommendations for specific Nexsan units on page 3 and Recommendations for all
Nexsan units on page 5.
2. Wherever possible, update your Nexsan RAID storage unit to the latest available firmware. Contact
Nexsan Technical Support (see Contacting service and support on page v) for assistance.
3. (E-Series units only) If you wish to implement VAAI (see VAAI overview on page 2), you must have
firmware version Q011.1101 or newer. See Update Firmware in Chapter 2 of the Nexsan High-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 the Nexsan High-Density Storage User Guide.
Path optimization
The Nexsan system supports all modes of VMware Multipathing.
► 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 high
or 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 VM’s to less-used Datastores.
4. Adjust port load by changing the primary fixed path in ESX Path management.
2
This applies to both iSCSI and Fibre Channel connections.
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Glossary
Glossary
1
10Gb Ethernet
A 10 gigabit per second (Gb/s) Ethernet
connection using either fiber-optic cables or
twisted-pair copper wires.
10Gb iSCSI
An iSCSI connection that runs on a 10Gb
Ethernet network.
10GbE
See “10Gb Ethernet” and “10Gb iSCSI”.
A
boot drive
The device from which a computer’s operating
system is loaded. Typically, an internal hard disk
drive (or one of several partitions on such a drive)
is used for this purpose, but any attached
storage device—such as an optical disc drive, a
USB flash drive, or other attached storage—can
be used.
byte
A unit of data that is 8 bits long. Often used for
alphanumeric characters. Abbreviated “B”.
C
Controller
See RAID Controller
D
Active Directory
Microsoft’s directory service, used by all
supported Windows operating systems.
Abbreviated “AD”.
DNS
See “Domain Name System”.
Domain Name System
A program or computer server that implements a
All Ports All LUNs (APAL) mode
name-service protocol. It maps a humanA system mode for Nexsan storage systems. In
recognizable identifier to a system-internal, often
this mode, the entire system operates as a single
numeric, identification or addressing component
node. The volumes can be mapped to any or all
(usually an IP address).
ports on both RAID controllers. When a
controller fails, the ports on that controller
become inaccessible. However, if the volumes
are mapped to ports on the other controller as
well (which requires the host to be configured for
E-Series
multipathing), they remain accessible to the
The series of Nexsan units that includes the
host, which sees the storage become active
Nexsan E18, E48, and E60 storage units (and
through its second path.
their V and VT variants), the Nexsan E32V, the
Nexsan E18X, E48X, and E60X expansion units
array
(and their XV variants), and the Nexsan E32XV.
A linked group of one or more physical,
Nexsan E-Series units feature Active Drawer
independent hard disk drives. See also “RAID”.
Technology, Anti-Vibration Design, and
CoolDrive Technology.
E
B
bit
Ethernet
A system for connecting a number of computer
systems to form a local area network (LAN), with
The smallest unit of digital data, representing a 0
protocols to control the passing of information
or a 1. Abbreviated “b”.
and to avoid simultaneous transmission by two
or more systems. Supports data transfer rates of
10, 100, 1,000, and 10,000 megabits per second
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Glossary
(Mb/s). 10, 100, and 1,000Mb/s networks are
often referred to as 10BASE-T, 100BASE-T, and
1000BASE-T, respectively. 10,000Mb/s
Gb
networks are usually referred to as 10Gb
Ethernet or 10GbE.
G
F
Gigabit. Approximately one billion
(1,000,000,000) bits.
GB
Gigabyte. Approximately one billion
(1,000,000,000) bytes. Used to describe the
storage 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 “binary
gigabyte” and abbreviated GiB).
failover
The capability of a system to switch over
automatically to a redundant or standby system
upon the failure or abnormal termination of the
previously active system. In Nexsan storage
systems, failover describes one RAID controller
taking over the host connections and RAID set Gb/s
control of the other RAID Controller when that
Gigabits (Gb) per second. Used to describe the
controller fails.
speed of network data transmission.
Fiber Channel
GB/s
A gigabit (Gb) speed network technology
Gigabytes (GB) per second. Used to describe
primarily used for storage networking and the
the speed of network data transmission. 1 GB/s
current standard connection type for storage area
is eight times faster than 1Gb/s.
networks (SANs). Despite its name, Fiber
Channel signaling can run on both twisted-pair GBIC
copper wire and fiber-optic cables.
See “gigabit interface converter”.
firmware
GiB
Small, fixed software applications, stored in
A binary gigabyte, computed as 2^30
read-only memory (ROM) or programmable read(1,073,741,824) bytes. See “GB”.
only memory (PROM), that internally control
various electronic devices. In Nexsan E-Series, gigabit interface converter
A standard for transceivers, commonly used with
SATABeast/SASBeast, and SATABoy/SASBoy
Gigabit (Gb) Ethernet and Fiber Channel, with a
storage systems, each RAID controller is loaded
hot-swappable electrical interface. Gigabit
with firmware to control its functionality.
interface converter ports can support a wide
Occasionally, this firmware must be updated
range of physical media, from copper to optical
using the Update Firmware page in the graphical
fiber, at lengths of up to hundreds of kilometers.
user interface.
graphical user interface
frame
A type of user interface that allows users to
A data packet on an Ethernet or Fiber Channel
interact with electronic devices using images
link. Each frame encapsulates a piece of data
rather than text commands. Nexsan storage
with sender and destination information, along
units use a graphical user interface for system
with a data integrity check routine. Normal
configuration.
frames can contain data up to 1,500 bytes in
length. Jumbo frames can contain larger data
GUI
payloads (9,000 bytes on Nexsan storage
See “graphical user interface”.
systems) and are supported on 1Gb/s and
10Gb/s Ethernet (10GbE) networks. Jumbo
frames are typically used to boost performance
of iSCSI traffic.
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Glossary
KB
H
Kilobyte. Approximately one thousand (1,000)
bytes. Used to describe the storage capacity of
hard disk drives and the stripe size in RAIDs. A
kilobyte 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” and
abbreviated KiB).
host
A computer, server, or other device which
accesses the volumes in a Nexsan storage
system. The host can be connected to the
Nexsan storage system with a Fiber Channel
connection, an iSCSI connection, or a SAS
connection.
KiB
A binary kilobyte. Computer as 2^10 (1,024)
bytes. See “KB”.
I
L
I/O
Input/Output. The communication between an
information processing system (such as a
load balance policy
computer or a Nexsan storage system’s
In multipathing, a set of instructions for the
RAID controller), and the outside world (either an
multipathing software to follow in order to ensure
operator or another information processing
that I/O transfers through host paths are
system). Inputs are the signals or data received
optimally routed and that no one path gets
by the system, and outputs are the signals or
overloaded with data.
data sent from it.
IP address
Internet Protocol address. A numerical label
assigned to each device (such as a computer,
printer, or Nexsan storage unit) on a computer
network that uses TCP/IP for communication.
logical unit
See “volume”.
LUN
Logical Unit Number. An identification scheme
for storage disks that supports a small number of
logical units. On Nexsan storage systems,
LUNs are assigned to volumes and are
addressed as LUN 0 through 254.
IP Configuration Tool
One of six Nexsan Storage Tools. Allows users
to configure the IP address of a Nexsan storage
system on the local subnet.
iSCSI
Internet Small Computer System Interface. A
transport protocol that provides for the SCSI
protocol to be carried over a TCP/IP network.
M
Mb
Megabit. Approximately one million (1,000,000)
bits.
MB
J
Megabyte. Approximately one million (1,000,000)
bytes. Used to describe the storage capacity of
hard disk drives. A megabyte is usually
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” and
abbreviated MiB).
jumbo frame
See “frame”.
K
Kb
Mb/s
Kilobit. Approximately one thousand (1,000) bits.
Nexsan High-Density Storage
VMware Best Practices Guide
Megabits (Mb) per second. Used to describe the
speed of network data transmission.
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18
Glossary
MB/s
Megabytes (MByte) per second. Used to
describe the speed of network data
transmission. 1 MB/s is eight times faster than
1Mb/s.
S
SCSI
Small Computer System Interface. A collection
of standards and proposed standards for
input/output (I/O) communication, primarily
intended for connecting storage subsystems or
devices to hosts.
MiB
A binary megabyte. Computed as 2^20
(1,048,576) bytes. See MByte.
multipathing
A means of presenting volumes to a particular
host or hosts via redundant data paths. The
TB
intent is to maintain I/O in the event of a path
failure. Multipathing may also be used to
increase performance. If not configured properly,
multipathing may lead to data corruption, as an
operating system may not inherently realize that
the redundant paths are of the same volume and
thus could treat them as different volumes.
T
R
Terabyte. Approximately one trillion
(1,000,000,000,000) bytes. Used to describe the
storage capacity of hard disk drives. A terabyte
is usually computed as 10^12
(1,000,000,000,000) bytes, but can also be
computed as 2^40 (1,099,511,627,776) bytes
(often called a “binary terabyte” and abbreviated
TiB).
TiB
A binary terabyte. Computed as 2^40
RAID
(1,099,511,627,776) bytes. See TB.
Redundant Array of Independent Disks. A
system using multiple hard drives organized into
a single logical unit for the sharing or replication
of data in order to increase data integrity, faulttolerance, and throughput. Also referred to as a
volume
RAID set. RAIDs are organized into
An area of usable storage that is addressed as a
RAID levels, which describe their architecture
single unit as if it were a separate, physical disk
and configuration.
drive. Volumes can exist on a single disk drive or
on a RAID that spans multiple disk drives.
RAID Controller
A hardware device, software program, or
combination of the two which manages the
physical disk drives in a RAID and presents
them as a single logical unit to attached devices.
The RAID Controllers in Nexsan storage units
are hardware modules. Nexsan RAID
Controllers also provide connections for system
administration and configuration.
V
reboot
To restart a computer or computerized electronic
device. See also system reboot.
19
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Nexsan — San Diego, USA
Nexsan — European Head Office, UK
910 E Hamilton Ave, Campbell
CA 95008, United States
Units 33–35 Parker Centre, Mansfield Road
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Technical Services:
Technical Services:
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Worldwide: 1.760.690.1111
Worldwide: 1.760.690.1111
Support E-mail: [email protected]
Support E-mail: [email protected]
Sales E-mail: [email protected]
Sales E-mail: [email protected]
Copyright © 2010–2016 Nexsan. All Rights Reserved.
This product is protected by one or more of the following patents, and other
pending patent applications worldwide: United States patents US8,191,841,
US8,120,922; United Kingdom patents GB2466535B, GB2467622B,
GB2467404B, GB2296798B, GB2297636B
Nexsan® and the Nexsan logo are trademarks or registered trademarks of
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Part Number: P0450150 Rev: A