HP LeftHand Storage DSM for MPIODeployment Guide

HP Part Number: AX696-96220Published: November 2012Edition: 2

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

1 Using MPIODescription 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 volumeresides, 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 beingrequested.

◦

◦ 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 systembased 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 storagesystem in the cluster. For example, in a cluster with five storage systems, DSM forMPIO-connected volumes have six iSCSI MPIO connections to the SAN, one for each storagesystem 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 asthe application server. Alternatively, you can assign an application server to a site. Applicationservers assigned to a site connect only to storage systems in the same site. Both of theseconfigurations permit higher performance and lower network utilization by reducing the amountof I/Os that traverse the WAN link.

:Refer to the instructions specific to Multi-Site SAN configurations in the rest of this chapter. Youcan also refer to the HP LeftHand Storage Multi-Site Configuration Guide, available on the HPLeftHand Management Software DVD or on the HP P4000 Manuals page of the HP BusinessSupport Center website.

http://www.hp.com/support/manuals

In the Storage section, navigate to Disk Storage Systems→P4000 SAN Solutions→HP LeftHandP4000 SAN Solutions or HP StorageWorks P4000 G2 SAN Solutions, depending upon your product.

Using Microsoft DSMBeginning with SAN/iQ software Version 9.0, you can use Microsoft DSM on your applicationservers. For additional information about the Microsoft DSM, see the MPIO white paper availablefrom 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 Robinoptions. For more information, see “Setting the Microsoft DSM MPIO load balancing policy”(page 8).

Using VMware ESX Server native MPIOWith 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 PracticesIf MPIO is not required, then do not install the DSM for MPIO or do not enable the Microsoft MPIOservice.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 willensure that reads are performed with a local replica when one is available. This is particularlyuseful for Microsoft clusters where a Microsoft cluster node is on each side of the inter-sitelink.

Configurations where the DSM for MPIO is not recommended:

• For any volumes that are accessed by ESX and Windows initiators (as might be done forVMware 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 MPIOmay 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 mightapply, multiply the expected number of volumes by the number of storage systems plus thenumber of server NICs.

NOTE: If the storage configuration is not recommended for DSM for MPIO, then uninstall theDSM for MPIO during the upgrade to V9.x and use the Microsoft DSM.

Installing the DSM for MPIO

Supported versions of Microsoft Windows ServerThe 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 2008with 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 MPIOand 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 MicrosoftiSCSI Initiator Driver Timers section of the Microsoft iSCSI Software Initiator Version 2.X UsersGuide.

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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 2008R2, or R2 Server Core installations

• The Microsoft iSCSI Initiator, which comes installed with all Windows Server 2008 and theServer Core installation

• The Microsoft Multipath IO optional component installed

If installing the DSM for MPIO into an existing Microsoft cluster1. 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/iQsoftware.

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 theMicrosoft MPIO Multipathing Support for iSCSI option when installing the Microsoft iSCSIInitiator.

◦ 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 ApplicationIntegration Solution Pack DVD to upgrade to Version 9.0.After upgrading to Version 9.0, use the new installer provided in the HP LeftHand ApplicationIntegration 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 option1. 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 MPIOOnce the DSM for MPIO or Microsoft DSM is installed on the server, all iSCSI volume connectionsmade to an iSCSI SAN will attempt to connect with the DSM. You do not need to configure themultiple I/O paths manually.If you are also using the Multi-Site SAN features, you can assign servers to specific sites to avoidhigh-latency connections between sites. For more information, see the HP LeftHand Storage Multi-SiteConfiguration Guide.

Connecting application servers with single or multiple NICs to volumesTo 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 Automaticallyrestore... 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.

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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 3 through 11 for the additional storage NICs.

Connecting volumes in a Multi-Site SANConnecting to volumes in a Multi-Site SAN is similar to connecting to volumes in a single-siteconfiguration, with a couple of important differences.

• For proper failover/failback configuration of a Multi-Site SAN you must configure all clusterVIPs for discovery. List the VIPs in the preferred order of connection. For example, if Site A isthe 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 SANUse the Virtual IP address of the HP LeftHand Storage cluster when connecting to volumes usingMPIO. In a Multi-Site SAN, you must enter the VIPs of all the multi-site clusters on all the applicationservers to take advantage of the DSM's multipath I/O capabilities. In addition, all the applicationservers 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 policyWhen you connect application servers to volumes, you can also set the MPIO load balancingpolicy in the iSCSI Initiator.

Supported load balancing optionsOnly two load balancing options are supported, Fail Over and Round Robin. For the MicrosoftDSM 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 betweenthe server and the storage. One path is actively used for I/O to the storage. The other pathsare 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 betweenthe 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 selectingFail 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 theMicrosoft 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 loadbalancing” (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

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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 optionsare available for Multiple Connected Session (Windows 2008) or Session Connections (Windows2003). 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 operationsAfter logging on to a volume via iSCSI, the DSM for MPIO automatically builds a data path toeach storage system in the cluster and one administrative path. You can verify the DSM for MPIOoperations by looking at the Details window of the iSCSI connection for the volume after loggingon to that volume.

Figure 8 Verifying the DSM for MPIO connections

What happens if a path fails with the DSM for MPIOIf one I/O path fails, volume I/O continues because additional active I/O paths to the iSCSI SANremain, as illustrated in Figure 9 (page 11).

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Figure 9 Multiple paths ensure continued I/O in event of path failure

When the problem with the I/O path is repaired, the DSM for MPIO reconnects an I/O path tothe storage system, thus restoring optimized performance and fault tolerance.

Verifying Microsoft DSM operationsIf you see two devices that are exactly the same listed in the Disk Manager or My Computer, youmay not have MPIO installed or you may not have logged using MPIO. For more information, see“Using Microsoft DSM” (page 3) and “Connecting volumes with MPIO” (page 6).

Trouble bringing disks onlineIf you cannot access volumes or do not see the disks (in Disk Manager or My Computer), you mayneed to bring the disks online. You may also see that the device in the iSCSI Initiator is listed witha device number —1 or with no device name. Use the following Windows utilities to solve theproblem:• The automount setting in theWindows 2008 andWindows 2008 R2 DiskPart Command-Line

affects whether disks will mount after changes in MPIO status, such as uninstalling genericMPIO or the DSM for MPIO.To run DiskPart, open a Windows command line and run diskpart.exe.For detailed information about the DiskPart Command-Line, see http://technet.microsoft.com/en-us/library/cc766465(WS.10).aspx.

• Log off all iSCSI sessions and use the command automount scrub to clean up volumemount point directories and registry settings for volumes that are no longer in the system. Thiscan clean up conflicting disk information that prevents disks from coming online. Informationabout automount is available by typing the command help automount from the diskpartcommand line.

• Check the SAN policy setting. The SAN policy should be set to Online All for SAN/iQ volumesto remount after uninstalling the DSM for MPIO. Information about the SAN policy is availableby typing the command help SAN from the diskpart command line.

Uninstalling the DSM for MPIOIMPORTANT: Uninstalling the DSM for MPIO requires a reboot of the system.

1. Log off all iSCSI sessions.2. Navigate to Control Panel and select Add or Remove Programs or Programs and Features,

depending on which version of Windows you are running.3. Remove the DSM for MPIO.4. Reboot the system.

Uninstalling the DSM for MPIO 11

Performing a silent uninstall for the Windows 2008 Server Core option

IMPORTANT: Uninstalling the DSM for MPIO requires a reboot of the system.

1. Open a command prompt and use the cd command to navigate to setup.exe in theinstallation media.

2. Type the following command:setup /removeonly /s /f1”.\uninst.iss”

3. The uninstall begins. You will see nothing until after a minute or two, when the server reboots.4. When the server is back up, check \Windows\dsminstall.log for errors.

12 Using MPIO

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