1. Managing HP Enterprise Virtual Array
HP EVA Multipathing
HP EVA Multipathing
Module 12
U4879S L.01
HP Education Services
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2. Managing HP Enterprise Virtual Array
Objectives
Managing HP Enterprise Virtual Array
HP EVA Multipathing
Address Active/Active lun presentation
Discuss multi-pathing concepts
Understand Load Balancing theory
Recognize the supported multipath/failover solutions for:
Windows
HP-UX
Linux (RHEL and SUSE)
ESX 4 server
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3. Active-Active Lun Presentation
Managing HP Enterprise Virtual Array
HP EVA Multipathing
HBA
ctrl A
vdisk
Array
Server
vdisk/lun owned by Controller A, but i/o goes thru ports on both controllers
Switch 1
Switch 2
ctrl B
All vdisks/luns have an owning controller, either Controller A or B
With Gen 1 EVA arrays, all read and write request from a host to a lun were sent thru paths to the owing controller only; when owning controller went down, alternate paths were used
All Gen 2, 3, and 4 EVA arrays accept read and write requests to both the owning and non-owning controllers simultaneously, improving performance on reads and writes
Read requests to the non-owning controller are not as optimal as to the owning, but when array detects high percentage (60%) of read I/Os processed by the non-owning controller, array will move lun to the other controller, optimizing read performance The result: enhanced performance
Instructor notes
This is a simplified version of A/A lun presentation. You may want to explain A/P and and outline the paths that would be used for a read/write, the explain the difference with A/A.
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4. Multi-Pathing Concepts
Managing HP Enterprise Virtual Array
HP EVA Multipathing
HBA
ctrl A
vdisk
Array
Server
Multipath
drivers
Normal operation
Switch 1
Switch 2
ctrl B
HP multipath solutions provide path virtualization to mask the fabric and disk array complexity
HP multipath solutions provide automatic path failover between a server and HP disk arrays
Up to 32 paths are supported per LUN
Some multipath solutions provide load balancing over multiple HBA paths
Various algorithms may be used
Administrator controlled
CLI and GUI available for management
Multipath software is not required for operating environments with native capability, such as: HP-UX 11iv3, Tru64 UNIX, OpenVMS, and VMware
The result: enhanced data availability
Instructor notes
Multipath solutions may provide:
Automatic path failover and recovery to an alternate path
Dynamic load balancing over multiple paths
Both CLI and GUI-based management tools
Benefit: enhanced data availability.
Primary path
Alternate path
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5. Automatic path failover
Managing HP Enterprise Virtual Array
HP EVA Multipathing
Failover functionality
Supported via services, agents and drivers
Failover is transparent to applications
CLI used to configure preferred/alternate paths
Supports Fibre Channel direct and Fibre Channel SAN connectivity
Works with many clustering solutions
Path changes are logged and may support automatic notification
Command View enables primary path with failover/failback; settings are dependant on the OS support
HBA
ctrl A
vdisk
Array
Server
Multipath
drivers
Switch 1
Switch 2
ctrl B
Failover operation
Instructor notes
If a data path fails, multipath software can automatically tries to switch to an alternate path. The failover is not visible to applications.
All path changes are logged allowing service personnel to investigate and repair failed paths. You can configure most multipath software to automatically send notification of failures.
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6. Managing HP Enterprise Virtual Array
Load balancing
Managing HP Enterprise Virtual Array
HP EVA Multipathing
Load balancing functionality
Provides load balancing across all installed HBAs (ports) in a server
There are various load balancing policies (depending on solution):
Round robin
Least I/O
Least bandwidth
Shortest queue (requests, bytes, service time)
No load balancing (off)
ALB (adaptive load balance, Windows only)
Instructor notes
Multipath software detects multiple paths to each logical device and allocates the data load among the paths for optimum performance.
Multipath load balancing prevents any path from becoming overloaded, and it helps to prevent the congestion that occurs when many I/O operations are directed to common devices along the same path.
Load balancing is performed using a policy selected by the administrator. The policies find the least busy path, as determined by requests, bytes, or service time.
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7. Supported Multi-path Solutions
Managing HP Enterprise Virtual Array
HP EVA Multipathing
Windows: HP MPIO full featured DSM for EVA v4.01
HP-UX: HP-UX has OS native multi-path (DMP); HP Secure Path 3.0F SP3 for HP-UX and prior versions; LVM pvlinks native in HP-UX
Linux: HP Device Mapper Multipath kit v4.x; QLogic Failover driver available from QLogic/HP; Emulex MultiPulse driver available from Emulex/HP
Tru64: native in OS
OpenVMS: native in OS
AIX: MPIO x or 1.0.1
Sun Solaris: MPxIO ; VERITAS DMP available from VERITAS; Sun/Solaris (x86) has native multipathing
NetWare: MPIO native in OS
Mac OS X: included with HBA
Vmware: N/A
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8. Windows: Full Featured MPIO DSM and DSM Manager
Managing HP Enterprise Virtual Array
HP EVA Multipathing
Windows: Full Featured MPIO DSM and DSM Manager
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9. Managing HP Enterprise Virtual Array
HP MPIO DSM
Managing HP Enterprise Virtual Array
HP EVA Multipathing
System requirements for installing HP MPIO full-featured DSM for Windows for EVA 4/6/8x00 disk arrays are:
Supported platforms
Windows Server 2003 with Service Pack 1 (x86, IA64 and x64)
Windows Server 2003 with Service Pack 2 (x86, IA64 and x64)
Windows Server 2003 R2 with Service Pack 2 (x86 and x64)
Windows Server 2008 (x86, IA64 and x64)
Windows Server 2008 – Server Core (x86 and x64)
40MB (approximately) free disk space.
Supported Fibre Channel host bus adapters (HBA) with the supported HBA driver and firmware installed (verify before MPIO installation)
Instructor notes
HP MPIO DSM 4.10 is the latest version.
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10. Managing HP Enterprise Virtual Array
Installing HP DSM
Managing HP Enterprise Virtual Array
HP EVA Multipathing
Win 2008
example
Instructor Notes
This is a Win 2008 example comes with the Microsoft MPIO framework installed so the HP DSM only needs to be installed normally. Pre-Win 2008 by default the MPIO Framework and DSM were installed at the same time. Reboot is required after installation.
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11. Installing DSM Manager and Notification Editor
Managing HP Enterprise Virtual Array
HP EVA Multipathing
DSM Manager integrates into MMC
Provides path and load balance options
Optional notification available
Configured during the installation (or later)
Select Cancel to configure later
Requires existing SMTP server
Instructor Notes
Adaptive Load Balance (ALB) is available as an enhancement to the other load balancing policies. When ALB is enabled, only optimal paths are used for load balancing. ALB’s primary function is to balance Read IOs, all writes must go to both controllers no matter what the load balancing setting is because of the need to mirror cache.
Optimal paths are paths to the controller that the lun is online to. For example, with an EVA 4400, there is a controller 1 and 2. The array has two host ports on each controller. If the lun is online to controller 1, then the optimal paths are the paths that use the FP1 and FP2 host ports on controller 1 only.
The practical effect of ALB is that all IO for a lun is distributed across the host ports of one controller. To distribute the IO between the two controllers using ALB, it is necessary to ensure that there are luns online to each controller in such a way that the IO is divided in the proportion desired.
Check ‘Enable ALB’ to use Asymmetric Logical Unit Access for the selected LUN
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12. Managing HP Enterprise Virtual Array
HP DSM utilities
Managing HP Enterprise Virtual Array
HP EVA Multipathing
hpdsm.exe
Instructor notes
HPDSM PR Utility; persistent binding reservation manager (used in MS Cluster configurations)
To bring up DSM utilities
Start/All Programs then Hewlett-Packard (Win 2008
Shown)
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13. Asymmetric Logical Unit Access (ALUA)
Managing HP Enterprise Virtual Array
HP EVA Multipathing
Asymmetric Logical Unit Access (ALUA)
Defined by INCITS T10 / Adaptive Load Balance
A LUN can be accessed trough multiple Target Ports.
Target Ports Groups can be defined to manage Target Ports with the same attributes
The ALUA inquiry string reports one of the following states/attributes:
Active/optimized
Active/non-optimized
Standby
Unavailable
Active/optimized path
Active/non-optimized path
HBA 1
HBA 2
Target Port Group n
Target Port Group 1
Target Port 1
Target Port 2
Target Port n
LUN
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14. Managing HP Enterprise Virtual Array
HPDSM CLI (hpdsm.exe)
Managing HP Enterprise Virtual Array
HP EVA Multipathing
Start  Programs  Hewlett-Packard  EVA DSM  HPDSM CLI
 hpdsm [options]
Command
Description
hpdsm devices
Displays details of devices
hpdsm paths device=#
Displays details of paths to device # (* at the end of a path signifies that it is the preferred path)
hpdsm set device=# path=#
Sets preferred path to device # as path #
hpdsm set device=# subset=add|remove path=#
Set up a subset of paths that are to be actively used
hpdsm set device=# policy=<policy_name>
Sets load balance policy for device #
hpdsm cleanup device=#
Removes the failed path information for the device #
hpdsm notify event=# time=#
registers for the notification of the event specified by event # with the time in minutes as time #
Instructor notes
The one command/option we do not discuss subsets you may want to mention what this option is used for.
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15. Managing HP Enterprise Virtual Array
hpdsm paths
Managing HP Enterprise Virtual Array
HP EVA Multipathing
Display device and storage system information:
primary path
lun number
In this example, LUN 1:
Controller B: SN=P8BC8F3AAS4028 (and is the owning controller)
Controller A: SN=P8BC8F3AAS3016
Path #4 becomes default path if load balance is disabled
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16. Setting storage system properties (hpdsm)
Managing HP Enterprise Virtual Array
HP EVA Multipathing
Set the following properties:
Load balancing
hpdsm set device=# policy=<policy_name>
where <policy_name> is one of:
NLB (No_Load_Balance) NLB
RR (Round_Robin)
SQR (Shortest_Queue_Requests)
SQB (Shortest_Queue_Bytes)
SQST (Shortest_Queue_Service_Time)
Adaptive load balancing
hpdsm set device=# alb=<policy_state>
where <policy_state> is one of:
n (adaptive load balance disabled)
y (adaptive load balance enabled)
Path preference (disables load balancing)
hpdsm set device=# path=#
Instructor notes
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17. Managing HP Enterprise Virtual Array
MPIO DSM Mgr
Managing HP Enterprise Virtual Array
HP EVA Multipathing
Load Balancing Policies
Preferred Path
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18. HP-UX: Native Load Balancing
Managing HP Enterprise Virtual Array
HP EVA Multipathing
HP-UX: Native Load Balancing
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19. HP-UX 11iv3 native multi-pathing
Managing HP Enterprise Virtual Array
HP EVA Multipathing
Load balancing policies available:
round_robin (default)
weighted_rr
least_cmd_load
preferred_path
pref_tport
cl_round_robin (for cell based systems)
closest_path (for cell based systems)
Managing load_balancing policies:
To view: scsimgr get_attr –a load_bal_policy
To modify: scsimgr set_attr –a load_bal_policy=<policy>
or scsimgr save_attr –a load_bal_policy=<policy>
To view statistics: scsimgr get_stat
HP-UX 11iv3 introduces native multi-pathing. All paths to a LUN are automatically discovered. The various paths to LUN devices are correlated based on a world-wide unique identifier (WWID) that is used to create a persistent DSF offering agile addressing.
The new scsimgr command can be used to view and configure various attributes of a device, including the load balancing policy. scsimgr also enables you to monitor the behavior of lunpaths and LUN components. Using error related statistics such as I/O errors and open errors system administrators can readily identify failing components and understand the cause of the failure.
Use scsimgr get_attr to view attributes. Use scsimgr set_attr to temporarily change attributes. Setting will revert back to the default after a reboot. Use scsimgr save_attr to permanently change an attribute. These changes will survive a reboot.
  The following load balancing policies are supported:
round_robin
LUN paths are selected in a round robin manner. This is more appropriate when all the paths to the device have similar I/O turn-around characteristics. This is the default.
Weighted round-robin (weighted_rr)
This policy distributes the I/O load across all active lunpaths in a round-robin manner and according to the weight assigned to each lunpath. A number of I/O operations corresponding to the weight of the lunpath is transferred on the same lunpath before another lunpath is selected. Lunpaths with a weight of 0 are excluded from I/O transfer. This is the best choice for an XP. Set the weight such that approximately 8MB will be transferred before a switch occurs.
least_cmd_load
The LUN path with the least number of active I/O requests is selected to execute the next I/O. This policy is appropriate when the paths to the LUN exhibit asymmetric latency characteristics. The load is distributed to optimize the bandwidth on each LUN path.
preferred_path
The LUN path set in the preferred_path attribute is preferably used for I/O transfer. If this LUN path is not available or if the preferred_path attribute was not set, any other path is selected for I/O transfer. Manual load balancing can be accomplished by selecting different preferred paths for different LUNs
pref_tport
LUN paths to the target port set in the pref_tport attribute are preferably used for I/O transfer in a round robin manner, when the I/O load balancing policy is set to pref_tport. If no LUN path to the preferred target port is available, or if the pref_tport attribute is not set, any other path is selected for I/O transfer. This policy allows you to ensure that I/O requests will go to the same CHA port while still taking advantage of multiple HBA connections to that CHA port.
cl_round_robin (cell aware round robin)
This load balancing policy is applicable to HP cell-based platforms. The LUN paths are selected in a round robin manner within the locality of CPU on which the I/O was initiated, to ensure that memory access latencies are optimized.
closest_path
The LUN path is selected based on its affinity with the CPU issuing the I/O so as to minimize latency. This policy is more appropriate on cell based platforms.
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20. HP-UX 11iv3 native multi-pathing examples
Managing HP Enterprise Virtual Array
HP EVA Multipathing
View load balancing policy
# scsimgr get_attr -D /dev/rdisk/disk10 -a load_bal_policy
SCSI ATTRIBUTES FOR LUN : /dev/rdisk/disk31
name = load_bal_policy
current = round_robin
default = round_robin
Setting load balancing policy
# scsimgr set_attr -D /dev/rdisk/disk10 \
-a load_bal_policy=least_cmd_load
# scsimgr save_attr -D /dev/rdisk/disk10 \
-a load_bal_policy=pref_tport \
-a pref_tport=0x50001fe150072fc9
SecurePath was used prior to 11iv3. This content was removed from the class materail. You may want to mention it but since it is no longer required for the new version of HPUX was taken out of the class materials except for the student notes.
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21. Linux: HP Device Mapper Multipath & HP Fibre Channel Enablement
Managing HP Enterprise Virtual Array
HP EVA Multipathing
Linux: HP Device Mapper Multipath & HP Fibre Channel Enablement
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22. Linux multipath solutions
Managing HP Enterprise Virtual Array
HP EVA Multipathing
Overview
HP Device Mapper Multipath kit 4.x
Works with various combinations of RHEL and SuSE OSes using QLogic or Emulex drivers
Recommended multipathing solution
Can be used with both OS and HP provided drivers
HP Fibre Channel Enablement Kit
Provides additional libraries and configuration utilities to enable HP StorageWorks fibre channel storage arrays to work with Linux.
Is not required to use the lpfc and qla2xxx kernel modules but it does provide configuration scripts to make sure that they the correct settings to work with HP StorageWorks FC arrays.
Sets the correct lpfc and qla2xxx kernel module setting that are used with Device Mapper Multipathing
QLogic and Emulex failover drivers
Instructor Notes
You may just want to mention at a high level the multipathing options for Linux and have the students look at the material themselves rather than going into a lot of detail on this subject.
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23. HP Device Mapper Multipath kit 4.x
Managing HP Enterprise Virtual Array
HP EVA Multipathing
Features
I/O failover and failback
Path grouping policies
I/O load balancing policies
Device name persistence
Persistent device settings
Device exclusion
Path monitoring
Online device addition and deletion
Management Utility
Boot from SAN
Cluster support
Volume Manager support
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24. HP Device Mapper Multipath kit 4.x
Managing HP Enterprise Virtual Array
HP EVA Multipathing
DM Multipath operation
On a Linux host, when there are multiple paths to a storage controller, each path appears as a separate block device and hence results in multiple block devices for single LUN.
DM Multipath creates a new Multipath block device for those devices that have the same LUN WWN.
Example
Host with two HBAs when attached to a storage controller with two ports through a single FC switch provides four block devices: /dev/sda, /dev/sdb, /dev/sdc, and /dev/sdd.
DM Multipath creates a single block device, /dev/mapper/mpath1, that reroutes I/O through these four underlying block devices
Obtaining and installation
Download the HPDM Multipath Enablement Kit for HP StorageWorks Disk Arrays v4.x available at
Log in as root to the host system.
Copy the installation tar package to a temporary directory (for example, /tmp/HPDMmultipath)
Unbundle the package by executing the following commands:
#cd /tmp/HPDMmultipath
#tar -xvzf HPDMmultipath tar.gz
#cd HPDMmultipath-4.3.0
Verify that the directory contains INSTALL, README.txt, COPYING, bin, SRPMS, conf, and docs directories.
To install, execute the following command:
#./INSTALL
Configuration (for FC HBAs)
To enable HP arrays, edit /etc/multipath.conf file by adding the following under devices section (installer does it automatically)
Configure HBA parameters (configured automatically by HP Fibre Channel Enablement Kit)
Edit the /etc/modprobe.conf file in RHEL hosts and /etc/modprobe.conf.local file in SLES hosts
Rebuild the initrd
Edit the value for default parameter in /boot/grub/menu.lst file to boot with the new initrd image
Reboot the host.
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25. HP Device Mapper Multipath kit 4.x
Managing HP Enterprise Virtual Array
HP EVA Multipathing
Using /etc/multipath.conf
Specify only the sections that you need for your configuration, or that you wish to change from the default.
Sections of the file that are not relevant to your environment or for which you do not need to override the default values, you can leave them commented out
The /etc/multipath.conf file consists of the following sections to configure the attributes of a multipath device:
System defaults (defaults)
Black-listed devices (blacklist)
Blacklist exceptions (blacklist_exceptions)
Storage array model settings (device)
Multipath device settings (multipaths)
/etc/multipath.conf
For EVA3000/EVA5000/EVA4x00/EVA6x00/EVA8x00
device {
vendor "(COMPAQ|HP)"
product "HSV1[01]1|HSV2[01]0|HSV300|HSV4[05]0"
getuid_callout "/sbin/scsi_id -g -u -s /block/%n"
prio_callout "/sbin/mpath_prio_alua /dev/%n"
hardware_handler "0"
path_selector "round-robin 0"
path_grouping_policy group_by_prio
failback immediate
rr_weight uniform
no_path_retry 18
rr_min_io 100
path_checker tur }
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26. HP Device Mapper Multipath kit 4.x
Managing HP Enterprise Virtual Array
HP EVA Multipathing
Black-listed devices (blacklist)
Devices that are blacklisted will not be grouped into a multipath device. Based on wwid ( using wwid ) or device names ( using devnode ) or vendor and product id ( using device block).
Blacklist exceptions (blacklist_exceptions)
List device names to be treated as multipath candidates even if they are on the blacklist.
Blacklist exceptions are only valid in the same class. It is not possible to blacklist devices using the devnode keyword and to exclude some devices of them using the wwid keyword
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27. HP Device Mapper Multipath kit 4.x
Managing HP Enterprise Virtual Array
HP EVA Multipathing
Storage array model settings (device)
If you need to add a storage device that is not supported by default
Overrides the attributes set in the defaults section
device {
vendor "HP|COMPAQ"
product "HSV1[01]1\(C\)COMPAQ|HSV[2][01]0|HSV300|HSV4[05]0"
path_grouping_policy group_by_prio
getuid_callout "/sbin/scsi_id -g -u -s /block/%n"
path_checker tur
path_selector "round-robin 0"
prio_callout "/sbin/mpath_prio_alua /dev/%n"
rr_weight uniform
failback immediate
hardware_handler "0"
no_path_retry
rr_min_io
Multi-path device settings:
multipath {
wwid
alias red
path_grouping_policy group_by_prio
path_selector "round-robin 0"
failback immediate
rr_weight uniform
no_path_retry
rr_min_io }
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28. HP Fibre Channel Enablement Kit
Managing HP Enterprise Virtual Array
HP EVA Multipathing
Installation
Download the hp-fc-enablement-yyyy-mm-dd.tar.gz file for your operating system and copy it to the target server
Untar the enablement kit and browse to the result directory
Do one of the following to execute the install.sh script:
If you are not using Device Mapper multipathing execute
# ./install.sh –s
If you are using Device Mapper multipathing execute
# ./install.sh –m
The hp-fc-enablement and fibreutils RPMs should be installed once this install completes. To verify the installation, enter the following commands:
# rpm -q hp-fc-enablement
# rpm -q fibreutils
/etc/multipath.conf
For EVA3000/EVA5000/EVA4x00/EVA6x00/EVA8x00
device {
vendor "(COMPAQ|HP)"
product "HSV1[01]1|HSV2[01]0|HSV300|HSV4[05]0"
getuid_callout "/sbin/scsi_id -g -u -s /block/%n"
prio_callout "/sbin/mpath_prio_alua /dev/%n"
hardware_handler "0"
path_selector "round-robin 0"
path_grouping_policy group_by_prio
failback immediate
rr_weight uniform
no_path_retry 18
rr_min_io 100
path_checker tur }
May need editing depending on OS. Check Device Mapper Multipath Enablement Kit for HP StorageWorks Disk Arrays v4.3.0 release notes for details
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29. Using HP Device Mapper Multipath and Fibre Channel Enablement Kit
Managing HP Enterprise Virtual Array
HP EVA Multipathing
Show Node and Port WWNs: adapter_info
Scan HBAs for new LUNs: hp_rescan
Starting HPDM multipath:
/etc/init.d/multipathd restart
/sbin/multipath
Show multipath topology: multipath -ll
/etc/multipath.conf
For EVA3000/EVA5000/EVA4x00/EVA6x00/EVA8x00
device {
vendor "(COMPAQ|HP)"
product "HSV1[01]1|HSV2[01]0|HSV300|HSV4[05]0"
getuid_callout "/sbin/scsi_id -g -u -s /block/%n"
prio_callout "/sbin/mpath_prio_alua /dev/%n"
hardware_handler "0"
path_selector "round-robin 0"
path_grouping_policy group_by_prio
failback immediate
rr_weight uniform
no_path_retry 18
rr_min_io 100
path_checker tur }
May need editing depending on OS. Check Device Mapper Multipath Enablement Kit for HP StorageWorks Disk Arrays v4.3.0 release notes for details
One LUN, presented to
2 ports accessible
via 4 paths
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30. Vmware ESX4 Server: Native multipathing via vSphere Client
Managing HP Enterprise Virtual Array
HP EVA Multipathing
Vmware ESX4 Server: Native multipathing via vSphere Client
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31. VMware ESX Server - Intro
Managing HP Enterprise Virtual Array
HP EVA Multipathing
Native multipathing management via vSphere Client GUI
Basic operations accessible from “Configuration->Storage Adapters”:
Disabling paths runing via choosen vmhba (Virtual Machine HBA)
Monitoring paths
More operations available with LUN’s “Manage Paths” menu
Paths disabling
Load Balancing policy setting
Fixed (static) path setting
Instructor Notes
You may just want to mention at a high level the multipathing options for VMware and have the students look at the material themselves rather than going into a lot of detail on this subject.
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32. VMware ESX Server – Basic operations
Managing HP Enterprise Virtual Array
HP EVA Multipathing
Configuration -> Storage Adapters
Select vmhba and switch view from Devices to Paths to monitor and/or disable paths running via choosen HBA
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33. VMware ESX Server – More operations
Managing HP Enterprise Virtual Array
HP EVA Multipathing
Configuration -> Storage Adapters
Select vmhba and switch view to Devices, right click at LUN and select “Manage Paths…”
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34. VMware ESX Server – Manage Paths
Managing HP Enterprise Virtual Array
HP EVA Multipathing
Path Selection policy
The pathing policies that can be used with ESX 4 are:
Most Recently Used (MRU) — Selects the first working path discovered at system boot time. If this path becomes unavailable, the ESX host switches to an alternative path and continues to use the new path while it is available. This is the default policy for LUNs presented from an Active/Passive array.
Fixed (Fixed) — Uses the designated preferred path, if it has been configured. Otherwise, it uses the first working path discovered at system boot time. If the ESX host cannot use the preferred path, it selects a random alternative available path. The ESX host automatically reverts back to the preferred path as soon as the path becomes available. This is the default policy for LUNs presented from an Active/Active array.
Round Robin (RR) – Uses an automatic path selection rotating through all available paths and enabling the distribution of the load across the paths. For Active/Passive arrays, only the paths to the active controller will used in the round robin. For Active/Active arrays, all paths will used in the round robin.
U4879S L.01 – © 2011 Hewlett-Packard Development Company, L.P.
U4879S L.01

35. Managing HP Enterprise Virtual Array
HP EVA Multipathing
Lab activity
U4879S L.01

36. Managing HP Enterprise Virtual Array
HP EVA Multipathing
U4879S L.01