HP Storevirtual 4000 Quick reference guide

HP LeftHand Storage DSM for MPIO
Deployment Guide
HP Part Number: AX696-96220
Published: November 2012
Edition: 2

© Copyright 2011, 2012 Hewlett-Packard Development Company, L.P.

1 Using MPIO
Description of the HP LeftHand DSM for Microsoft MPIO
The HP LeftHand DSM for Microsoft MPIO provides enhanced MPIO functionality as follows:
•Automatic creation of an I/O path to each storage system in the cluster on which the volume
resides, plus a path for the administrative connection.
•Improved performance architecture over native MPIO solutions:
Read I/Os are always serviced by a storage system that holds a copy of the data being
requested.
◦
◦Write I/Os are always serviced by a storage system that receives a copy of the data.
Remaining copies (replicas) of the data are forwarded to the appropriate storage system
based on the data protection level of the volume.
•The ability to build a robust, fault-tolerant solution because an I/O path is built to every storage
system in the cluster. For example, in a cluster with five storage systems, DSM for
MPIO-connected volumes have six iSCSI MPIO connections to the SAN, one for each storage
system and one for the administrative connection. Five of the six connections could go offline,
and I/O would still be serviced.
The DSM for MPIO supports connecting multiple NICs in the application server to the SAN.
Configuring with multiple NICs improves fault-tolerant physical network connections in the server.
The DSM for MPIO can be used in a Multi-Site SAN with one or more subnets. In this configuration,
the DSM for MPIO will only build I/O paths to the storage systems that are in the same subnet as
the application server. Alternatively, you can assign an application server to a site. Application
servers assigned to a site connect only to storage systems in the same site. Both of these
configurations permit higher performance and lower network utilization by reducing the amount
of I/Os that traverse the WAN link.
:
Refer to the instructions specific to Multi-Site SAN configurations in the rest of this chapter. You
can also refer to the HP LeftHand Storage Multi-Site Configuration Guide, available on the HP
LeftHand Management Software DVD or on the HP P4000 Manuals page of the HP Business
Support Center website.
http://www.hp.com/support/manuals
In the Storage section, navigate to Disk Storage Systems→P4000 SAN Solutions→HP LeftHand
P4000 SAN Solutions or HP StorageWorks P4000 G2 SAN Solutions, depending upon your product.
Using Microsoft DSM
Beginning with SAN/iQ software Version 9.0, you can use Microsoft DSM on your application
servers. For additional information about the Microsoft DSM, see the MPIO white paper available
from the Microsoft website:
http://www.microsoft.com/download/en/details.aspx?id=9787
When setting up the MPIO load balancing policy, use only the Fail Over Only or Round Robin
options. For more information, see “Setting the Microsoft DSM MPIO load balancing policy”
(page 8).
Using VMware ESX Server native MPIO
With VMware ESX, use the native ESX MPIO. For more information, see http://
h20195.www2.hp.com/V2/GetDocument.aspx?docname=4AA3-0261ENW.
Description of the HP LeftHand DSM for Microsoft MPIO 3

Best Practices
If MPIO is not required, then do not install the DSM for MPIO or do not enable the Microsoft MPIO
service.
If currently using the DSM for MPIO, then upgrade to the latest version.
Recommended uses for DSM for MPIO:
•For maximum possible performance for specified configurations.
•With Multi-Site SAN storage clusters, the DSM for MPIO with site preference is recommended,
particularly if the inter-site link is significantly slower than local access. This configuration will
ensure that reads are performed with a local replica when one is available. This is particularly
useful for Microsoft clusters where a Microsoft cluster node is on each side of the inter-site
link.
Configurations where the DSM for MPIO is not recommended:
•For any volumes that are accessed by ESX and Windows initiators (as might be done for
VMware Consolidated backup) do not use the DSM for MPIO.
•Configurations requiring connections through storage routers.
•Large Hyper-V clusters (either large storage cluster or many server NICs).
•Large storage clusters with simultaneous access to many volumes using the DSM for MPIO
may encounter the Microsoft limit of 255 iSCSI sessions. In this case, use Microsoft MPIO,
which uses fewer sessions. To determine whether the Microsoft MPIO iSCSI session limit might
apply, multiply the expected number of volumes by the number of storage systems plus the
number of server NICs.
NOTE: If the storage configuration is not recommended for DSM for MPIO, then uninstall the
DSM for MPIO during the upgrade to V9.x and use the Microsoft DSM.
Installing the DSM for MPIO
Supported versions of Microsoft Windows Server
The DSM for MPIO supports the following versions of Microsoft Windows Server.
•Windows Server 2003, Windows Server 2003 with Service Pack 1
•Windows Server 2003 SP1
•Windows Server 2008, Windows Server 2008 with Service Pack 1, Windows Server 2008
with Service Pack 2
•Windows Server 2008 Server Core
•Windows Server 2008 R2
•Windows Server 2008 R2 Server Core
•Windows Server 2012 Datacenter
NOTE: To help avoid issues with active/passive MPIO configurations (both the DSM for MPIO
and Microsoft DSM) and disk timeout errors when the iSCSI initiator detect a failure and reconnects,
you may want to change the EnableNOPOut registry setting to 1 as described in the Microsoft
iSCSI Initiator Driver Timers section of the Microsoft iSCSI Software Initiator Version 2.X Users
Guide.
4 Using MPIO

Prerequisites
Windows Server 2003
•32-bit or 64-bit version of Windows Server 2003
•The latest Microsoft iSCSI Initiator
•Microsoft DSM installed
Windows Server 2008 and Server Core option
•32-bit or 64-bit version of Windows Server 2008, the Server Core, Windows Server 2008
R2, or R2 Server Core installations
•The Microsoft iSCSI Initiator, which comes installed with all Windows Server 2008 and the
Server Core installation
•The Microsoft Multipath IO optional component installed
If installing the DSM for MPIO into an existing Microsoft cluster
1. Move all cluster resources and related file shares to one system that will stay active.
2. Pause the system that holds no resources and install the DSM for MPIO.
Updating the DSM for MPIO
NOTE: The preferred update order is to update the DSM for MPIO first, then update the SAN/iQ
software.
Choose one of the following options:
•If you are running a Version 7.x of the DSM for MPIO
◦Uninstall the previous version of the DSM for MPIO.
◦Reboot the server.
◦Download and install the latest version of the MS iSCSI Initiator. You must select the
Microsoft MPIO Multipathing Support for iSCSI option when installing the Microsoft iSCSI
Initiator.
◦Install the Version 9.x DSM for MPIO.
•If you are running Version 8.0 or 8.1 of the DSM for MPIO, use the HP LeftHand Application
Integration Solution Pack DVD to upgrade to Version 9.0.
After upgrading to Version 9.0, use the new installer provided in the HP LeftHand Application
Integration Solution Pack DVD.
To install the DSM for MPIO
IMPORTANT: Installing the DSM for MPIO requires a server reboot to complete the installation.
1. Begin the installer one of the following ways:
•Insert the HP LeftHand Application Integration Solution Pack DVD in the DVD drive.
•Double-click the executable that you downloaded to start the installation.
2. From the Home page of HP LeftHand Application Integration Solution Pack installer, click DSM
for MPIO.
3. From the HP LeftHand DSM for Microsoft MPIO page, click Install DSM for MPIO to begin the
installer.
Installing the DSM for MPIO 5

4. Accept the terms of the license agreement and click Next.
The installation wizard takes you through the installation process for the DSM for MPIO.
5. Reboot the server to complete the installation.
Perform a silent install for Windows Server 2008 Server Core option
1. Open a command prompt and use the cd command to navigate to setup.exe in the
installation media.
2. Type the following command:
setup /s /f1".\setup.iss"
The setup begins. You will see nothing until after a minute or two, when the server reboots.
3. When the server is back up, check \Windows\dsminstall.log for errors.
Connecting volumes with MPIO
Once the DSM for MPIO or Microsoft DSM is installed on the server, all iSCSI volume connections
made to an iSCSI SAN will attempt to connect with the DSM. You do not need to configure the
multiple I/O paths manually.
If you are also using the Multi-Site SAN features, you can assign servers to specific sites to avoid
high-latency connections between sites. For more information, see the HP LeftHand Storage Multi-Site
Configuration Guide.
Connecting application servers with single or multiple NICs to volumes
To connect to the volumes using the iSCSI Initiator:
1. Open the iSCSI Initiator.
2. On the Discovery tab, enter the VIP address of the cluster.
3. On the Targets tab, select the volume to log on to.
4. Click Log On.
5. Select the Enable multi-path check box.
Figure 1 Enabling multi-path for DSM
6. [Optional] If you want this volume to be available after rebooting, select the Automatically
restore... check box.
7. Click Advanced to open the Advanced Settings window.
8. Configure the Advanced Settings as follows:
•For Local adaptor, select Microsoft iSCSI initiator.
•For Source IP, select the IP address of the storage NIC to connect to the volume.
•For Target portal, select the VIP of the cluster containing the volume.
6 Using MPIO

Figure 2 Configuring advanced settings for multiple NICs
9. Click OK to close the Advanced Settings dialog.
10. Click OK again to finish logging on.
11. If you want to set the MPIO load balancing policy, see “Setting the Microsoft DSM MPIO load
balancing policy” (page 8).
12. If you have multiple NICs, repeat steps 3through 11 for the additional storage NICs.
Connecting volumes in a Multi-Site SAN
Connecting to volumes in a Multi-Site SAN is similar to connecting to volumes in a single-site
configuration, with a couple of important differences.
•For proper failover/failback configuration of a Multi-Site SAN you must configure all cluster
VIPs for discovery. List the VIPs in the preferred order of connection. For example, if Site A is
the first preference for connection, put the VIP associated to Site A first in the discovery list.
•You must also log on to the volumes with the default Target Portal setting.
Using multiple cluster VIPs when connecting to a Multi-Site SAN
Use the Virtual IP address of the HP LeftHand Storage cluster when connecting to volumes using
MPIO. In a Multi-Site SAN, you must enter the VIPs of all the multi-site clusters on all the application
servers to take advantage of the DSM's multipath I/O capabilities. In addition, all the application
servers must have the VIPs listed in the same order.
A sample Multi-Site SAN configuration is shown. In this configuration, the cluster has three sites:
Site A, Site B, and Site C. Site A is primary.
Connecting volumes with MPIO 7

Figure 3 Multi-site SAN VIPs with MPIO
Setting the Microsoft DSM MPIO load balancing policy
When you connect application servers to volumes, you can also set the MPIO load balancing
policy in the iSCSI Initiator.
Supported load balancing options
Only two load balancing options are supported, Fail Over and Round Robin. For the Microsoft
DSM with Windows 2003 Server, only the Fail Over Only option is supported.
•Fail Over Only – Also called active/passive MPIO. Two (or more) I/O paths are built between
the server and the storage. One path is actively used for I/O to the storage. The other paths
are available for failover only in the event the primary path goes down.
•Round Robin – Also called active/active MPIO. Two (or more) I/O paths are built between
the server and the storage. All paths are actively used for I/O to the storage.
In the DSM for MPIO, Vendor Specific is selected by default. This option is the same as selecting
Fail Over Only and will not be available after you select another option. In the Microsoft DSM,
Fail Over Only is the default selection for all Windows versions, except for Windows 2008 R2,
for which Round Robin is the default.
The MPIO load balancing policy affects the number of iSCSI connections created to the volume.
The number of connections also differs based on whether you are using the DSM for MPIO or the
Microsoft DSM. “DSM for MPIO with two NICs in the server and Failover MPIO load balancing”
(page 8) through “Microsoft DSM with two NICs in the server and Round Robin MPIO load
balancing” (page 9) show the connections created with applications servers that have two NICs.
Figure 4 DSM for MPIO with two NICs in the server and Failover MPIO load balancing
8 Using MPIO

Figure 5 DSM for MPIO with two NICs in the server and Round Robin MPIO load balancing
Figure 6 Microsoft DSM with two NICs in the server and Fail Over MPIO load balancing
Figure 7 Microsoft DSM with two NICs in the server and Round Robin MPIO load balancing
NOTE: Be sure to follow the steps below to set the MPIO load balancing policy. Similar options
are available for Multiple Connected Session (Windows 2008) or Session Connections (Windows
2003). These session load balancing policies will have no effect.
To set the MPIO load balancing policy:
1. Select the target you just logged on to and click Details.
2. Select the Devices tab.
3. Click Advanced.
This step is not needed for Windows 2008 Server R2.
Connecting volumes with MPIO 9

4. Click the MPIO button or tab.
If the MPIO button or tab is not available, MPIO is not installed and enabled.
5. From the Load balancing policy drop-down list, select either Fail Over Only or Round Robin.
6. Click OK.
7. Click OK.
Troubleshooting MPIO
Verifying DSM for MPIO operations
After logging on to a volume via iSCSI, the DSM for MPIO automatically builds a data path to
each storage system in the cluster and one administrative path. You can verify the DSM for MPIO
operations by looking at the Details window of the iSCSI connection for the volume after logging
on to that volume.
Figure 8 Verifying the DSM for MPIO connections
What happens if a path fails with the DSM for MPIO
If one I/O path fails, volume I/O continues because additional active I/O paths to the iSCSI SAN
remain, as illustrated in Figure 9 (page 11).
10 Using MPIO