Compellent Storage Center

Transcription

1 Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices Guide Dell Compellent Technical Solutions Group October 2012

2 THIS BEST PRACTICES GUIDE IS FOR INFORMATIONAL PURPOSES ONLY, AND MAY CONTAIN TYPOGRAPHICAL ERRORS AND TECHNICAL INACCURACIES. THE CONTENT IS PROVIDED AS IS, WITHOUT EXPRESS OR IMPLIED WARRANTIES OF ANY KIND Dell Inc. All rights reserved. Reproduction of this material in any manner whatsoever without the express written permission of Dell Inc. is strictly forbidden. For more information, contact Dell. Dell, the DELL logo, and the DELL badge are trademarks of Dell Inc. Microsoft and Windows are either trademarks or registered trademarks of Microsoft Corporation in the United States and/or other countries. Other trademarks and trade names may be used in this document to refer to either the entities claiming the marks and names or their products. Dell disclaims any proprietary interest in the marks and names of others. ii

3 Table of Contents 1 Preface Audience Purpose Customer Support Introduction Introduction to Microsoft Multipath IO (MPIO) Dell Compellent Storage Center connections Legacy ports Virtual ports Conclusion Configuring servers Fibre Channel iscsi Automatic configuration Manual configuration Verifying connectivity Choosing the IO transport Using MPIO on Windows Server Dell Compellent Multipath Manager Configuration Which policy should you choose? iscsi multipath options Installing the Microsoft iscsi DSM Configuring the iscsi Initiator Configuring Microsoft iscsi DSM Using MPIO on Windows Server 2008 and 2008 R Installing the Microsoft MPIO DSM Server Manager GUI Server Manager CLI (2008 and 2008 R2 only) To install MPIO on server core: iii

4 5.2 Associating Dell Compellent volumes with the DSM Setting the default load balance policy Windows Server 2008 default load balance policy Windows Server 2008 R2 default load balance policy Per-volume load balance settings Using MPCLAIM in 2008 R Using MPIO on Windows Server Installing the Microsoft MPIO Feature Server Manager GUI PowerShell Associating Dell Compellent volumes with the In-box DSM Using the MPIO Control Panel Using PowerShell Setting the default load-balancing policy Per-volume load balance settings Using the Disk Management GUI: Using PowerShell: Additional Resources iv

5 Document Revisions Date Revision Author Comments 10/11/ Technical Solutions Initial Draft 10/21/ Technical Solutions Corrected Errors 11/29/ Technical Solutions Additional content on Server Core 10/15/ Technical Solutions Updated to include Windows Server 2012 content October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 1

6 1 Preface 1.1 Audience The audience for this document is System Administrators who are responsible for the setup and maintenance of Windows servers and associated storage. Readers should have a working knowledge of Windows and the Dell Compellent Storage Center. 1.2 Purpose This document provides an overview of MPIO and introduces best practice guidelines for configuring MPIO on Windows server 2003, 2008, 2008 R2, and 2012 when using the Dell Compellent Storage Center. For installation procedures, download the MPIO Users Guide from Customer Support Dell Compellent provides live support EZSTORE ( ), 24 hours a day, 7 days a week, 365 days a year. For additional support, Dell Compellent at support@compellent.com. Dell Compellent responds to s during normal business hours. October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 2

7 2 Introduction 2.1 Introduction to Microsoft Multipath IO (MPIO) Microsoft Multipath I/O (MPIO) is a framework that allows administrators to configure load balancing and failover processes for Fibre Channel and iscsi connected storage devices. You can configure load balancing to use up to 32 independent paths from the connected storage devices Although Dell Compellent Storage Centers provide redundancy and failover with multiple controllers and RAID, servers still need a way to spread the IO load and handle internal failover from one path to the next. This is where MPIO plays an important role. Without MPIO, servers see multiple instances of the same disk device in Disk Management. The MPIO framework uses Device Specific Modules (DSM) to allow path configuration. Currently there are two options available Microsoft provides a built-in generic Microsoft DSM (MSDSM) for Windows Server 2008 and above. For Windows Server 2008 and above, use the MSDSM; it provides adequate functionality for Dell Compellent customers. Dell Compellent provides a DSM for Windows Server 2003 only. October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 3

8 2.2 Dell Compellent Storage Center connections Before reviewing server-specific MPIO functions, you must understand various connection options available with the Dell Compellent Storage Center that allow multiple paths to be presented to the servers. The following section provides a quick overview and explains the differences between Legacy Ports and Virtual Ports. This overview does not take the place of the Storage Center Connectivity Guide available on Legacy ports In legacy mode, front-end IO ports are broken into primary and reserve ports based on a fault domain. Primary/reserved ports allow IO to use the primary path; the reserve port is in a standby mode until a primary port fails over to the reserve port. In terms of MPIO, this requires twice the IO ports to enable multiple paths. Even more ports are required for a dual fabric. Figure 1 illustrates dual-fabric failover ports in legacy mode. Figure 1: Legacy Primary/Reserve Configuration Figure 1 shows four fault domains to the CT-SC040. Each fault domain has a primary and reserved port. For redundancy, a primary port connects to one controller; the reserved port in that fault domain connects to the other controller. While this is a highly robust failover solution, it requires a large number of ports. For this reason, Dell Compellent implemented Virtual Ports. October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 4

9 2.2.2 Virtual ports Dell Compellent introduced Virtual Ports in Storage Center 5.0. Virtual Ports allow all frontend IO ports to be virtualized. All front-end IO ports can be used at the same time for load balancing as well as failover to another port. Virtual Ports are available for Fibre Channel connections only, iscsi connections only, or both Fibre Channel and iscsi. Fibre Channel To use Virtual Ports for Fibre Channel, all Fibre Channel switches and HBAs must support NPIV (N_Port ID Virtualization). Figure 2: Virtual Ports Configuration Figure 2 shows a Virtual Port configuration. All ports of one transport type (Fibre Channel or iscsi) are in the same fault domain. All ports are active. If one port fails, the load is distributed between the remaining ports. Failover is just as robust as shown in Figure 1, with half the ports. iscsi iscsi follows the same wiring and port setup as Fibre Channel with the exception of the Control Port. iscsi uses a Control Port configured for each of the Fault Domains. Servers connect to the Control Port, which then redirects traffic to the appropriate virtual port. When configuring MPIO, this looks slightly different than with the Legacy Mode configuration because you need to assign only the Control Port in the iscsi Initiator software. These differences are covered later in the OS-specific sections Conclusion There are two methods to enable multiple paths from the Dell Compellent Storage Center, legacy ports and Virtual Ports. Virtual Ports are preferred because they reduce the number of HBAs required and thus reduce cost and overhead. Note that Virtual Ports are enabled based on protocol: you can enable Virtual Ports on Fibre Channel only, iscsi only, or both. October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 5

10 3 Configuring servers Before configuring MPIO at the operating system level, configure servers in the Dell Compellent System Manager. The following example assumes a server has two or more Fibre Channel or iscsi IO ports that are zoned/vlan to see the controller HBAs. With Fibre Channel, the process is the same for Virtual Ports as for legacy ports. However, with Legacy Ports the server cannot see Reserve ports. iscsi Virtual Ports connect only to a Control Port on the controller Fibre Channel To create the server, properly zone the switches so that the server and controller ports are in the same zone. The easiest way to do this is to boot the server into the card's BIOS and scan the SCSI devices on each port. An alternate method is to preconfigure the WWN's of the HBAs in the Storage Center System Manager iscsi As with Fibre Channel, you can create an iscsi server automatically or manually. For automatic configuration, enter the IP address of the controller HBA ports in the server iscsi HBA or Initiator Software. Use either the HBA BIOS or the Software Initiator configuration wizard. In Virtual Port mode, enter the IP address of the Control Port. In Legacy mode, enter the IP address of the primary port. This is covered in more detail in the OS sections. However, creating a server in the Storage Center is the same on all operating systems. October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 6

11 3.2 Automatic configuration Once a server has scanned for devices or logged into the target, Storage Center automatically recognizes the WWN/IQN. To configure a server: 1. Login to the Dell Compellent System Manager. 2. In the tree view, right-click on Servers. 3. From the shortcut menu, select Create Server. 4. Select the appropriate HBAs and continue the wizard. If the HBA does not appear, refer to Manual Configuration. Note: If the WWN or IQN is not listed, make sure that the Only Show Up Connections box is unchecked. Figure 3: Create Server October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 7

12 3.3 Manual configuration To manually configure an HBA: 1. In the Create Server wizard shown in Figure 3, click Manually Define HBA. 2. In the Select Transport Type window, choose Fibre Channel or iscsi. 3. Enter the WWN or iscsi name. Click Continue. Repeat for every WWN or iscsi HBA to be associated with the server. 4. Once HBAs are added, check the appropriate HBA and continue the wizard. Note: The new HBA appears with a red X. Once the server is connected the red X is removed. Figure 4: Manually defined HBA October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 8

13 3.4 Verifying connectivity To verify that the connectivity is correct: 1. In the tree view, select a Server. 2. Click on Connectivity. This window shows all paths available to the server based on the HBA and controller ports. Figure 5: Connectivity Tab The connectivity tab displays HBAs and controller ports the server can see. For Fibre Channel there are four possible paths: two HBAs see two Storage Center ports. However for iscsi there are a total of six connections: two separate IP Addresses going to three Storage Center ports. If MPIO is not installed and the volume is mapped using the default mapping method, the server has visibility to a total of 10 paths to a volume. October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 9

14 In Storage Center, a volume is mapped to all available paths unless you use the advanced mapping button to restrict mapping paths to FC only, iscsi only, or specified HBA ports and controller ports. To restrict mapping paths: 1. In the tree view, right-click on a Volume. 2. From the shortcut menu, select Map Volume to Server. The Map Volume to Server window appears. 3. Select a server and click Continue. The Map Volume window appears. 4. Click Advanced. 5. Check Only map using specified server ports. 6. Select one of the following: a. Limit ports by transport type. Select a transport from the drop-down menu. or b. Map using specific server ports. Check the specific server ports. Figure 6: Advanced Mapping Wizard October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 10

15 Assuming the default mapping wizard is used and paths are not restricted, a volume is mapped to all available paths, creating multiple IO paths from the server to the volume. To view the mapped paths: 1. In the tree view, select a volume. 2. Click on the Mapping tab. Figure 7: Volume Mapping Tab Figure 7 shows that MPIO Volume 1 was mapped to the server with four FC ports and two iscsi ports. 3.5 Choosing the IO transport Most organizations today have settled on Fibre Channel or iscsi for the IO transport mechanism. With the advent of 10GB iscsi, the difference in performance characteristics between these two protocols has gotten smaller. Choosing between these two depends on what the organization has in place today and where they are heading in the future. Dell Compellent offers both 8GB Fibre Channel and 10GB iscsi. If you are looking for a converged fabric then iscsi may be the best option because it can utilize existing networking infrastructure. However for most organizations, Fibre Channel remains the top choice for high bandwidth enterprise applications. The remainder of this document focuses on specific MPIO configuration options available from: Windows Server 2003 Dell Compellent provided DSM Windows Server 2008 and above MSDSM Microsoft iscsi DSM. It is assumed that there are multiple Front-End paths to the servers and that the servers have multiple connections to the controller. October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 11

16 4 Using MPIO on Windows Server 2003 Windows Server 2003 offers two methods for handling MPIO: Storage Center ISV-provided DSM. Microsoft iscsi DSM. These two methods cannot be used concurrently in the Windows 2003 platform. This chapter describes each of these options and provides guidance on how to configure MPIO with both the Storage Center DSM and the Microsoft DSM. 4.1 Dell Compellent Multipath Manager The Dell Compellent Multipath Manager is a Dell Compellent-provided DSM that handles all Fibre Channel and iscsi failover and load balancing. Fibre Channel requires the Dell Compellent Multipath Manager. iscsi can be configured with either the Microsoft iscsi DSM or the Dell Compellent Multipath Manager. For information on installing and configuring the Dell Compellent Multipath Manager, refer to the Storage Center Multipath IO (MPIO) Manager for Microsoft Servers User Guide on the Dell Compellent Knowledge Center. Once the Dell Compellent DSM has been installed, configure the load balance policies for the volumes attached to the server. The default Load Balance policy for the Dell Compellent DSM is Failover-Only. However, this can be changed to Round Robin or Round Robin Subset. Failover Only: Only one path is Active. IO fails over to the next available Standby path only when the Active path fails. The new Active path remains Active until another failover occurs. By default, the first discovered path is the Active path. You can configure the Failover Only policy to behave as Failback by setting the Active path and enabling the Preferred Path option. For Failback, the system fails back to the original Active path when it becomes available after a failover. Round Robin: All paths are active and IO is distributed across all paths. Round Robin Subset. Allows multiple Active and Standby paths and IO is distributed across all Active paths. Standby paths are used only when all Active paths fail. You can configure the Round Robin Subset policy to behave as Failback by explicitly setting one or more Active paths. For Failback, the system fails back to the original Active path when it becomes available after a failover. October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 12

17 4.2 Configuration To configure the default Load Balance policy or to change the active configuration of the DSM, open the Dell Compellent Multipath Manager Configuration wizard from the Program Files menu. Below is a brief overview of how to change the policies. Figure 8: Multipath Manager Configuration To change the default load balance policy for all future volumes attached to the system: 1. Click Set Default Policy at the top of the screen. 2. In the Policy field, select a policy for the environment. Figure 9: Set Default Policy October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 13

18 To change the policy for a given device: 1. Click on the device. 2. From the drop down menu, set the load balance policy. Note: If moving to a Round Robin policy, notice that the device paths do not change from Standby to Active until the settings are applied and the wizard is restarted or refreshed. 4.3 Which policy should you choose? Determining the best failover policy is accomplished by deciding which is more important for the application: failover, performance, or a combination of both. Cost also plays a significant role in the decision since having multiple paths adds to the overall cost of a solution. However, in today's world of zero downtime, failover is required in most organizations. As mentioned previously in Failover Only mode, the server uses only one path at a time. While this ensures redundancy, it may not provide adequate bandwidth for certain workloads. Also, any IO ports in standby mode are sitting idle until a failover occurs, resulting in underutilized resources in a data center. Round Robin, on the other hand, provides a means for IO to traverse all available paths while still providing a level of redundancy. If one path fails, the system uses the remaining paths to complete the request. Round Robin Subset is a mix of both of the above policies and provides greater granularity for managing when and where IO travels. With Round Robin Subset, you can group a set of ports to provide the benefits of round robin performance and provide a means for failover and failback with an alternate path or group of paths. Round Robin Subset is most commonly used when utilizing both FC and iscsi transports for the same volume. October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 14

19 4.4 iscsi multipath options As mentioned previously, the Dell Compellent Multipath Manager handles both FC and iscsi connections. In the Dell Compellent Configuration window, you can see the transport for each connection and configure them for each volume. Figure 10: Dell Compellent DSM with both FC and iscsi However, if you install the built-in Microsoft iscsi DSM, the Dell Compellent Multipath Manager software must be uninstalled. Typically this is done for a server with volumes connected only via an iscsi transport. Otherwise there is no way to control the Fibre Channel MPIO functionality. If the server has both transports in Windows Server 2003, the best practice is to use the Dell Compellent DSM and not install the Microsoft iscsi DSM Installing the Microsoft iscsi DSM To install the MS iscsi DSM, simply install the iscsi initiator software and select the checkbox next to Microsoft MPIO Multipathing Support for iscsi. Figure 11: Installing MS iscsi DSM Once installed, all iscsi volume MPIO characteristics are controlled by the MS iscsi DSM. Before jumping into MPIO configuration with iscsi you need to understand connecting and configuring the iscsi initiator. October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 15

20 4.5 Configuring the iscsi Initiator Whether you use the MS DSM or the Dell Compellent DSM for iscsi, the server must first be configured to communicate with the Dell Compellent iscsi front-end ports. This section describes how to configure the iscsi Initiator and make this connection. It assumes that the initiator software is installed, the server has been rebooted, and the Dell Compellent Storage Center has two or more iscsi front-end ports. In the following examples, the server is configured with two NIC cards, each used to communicate with the iscsi network. To configure the connection to the Dell Compellent Storage Center: 1. Open the iscsi Initiator. 2. Click on the Discovery tab. The Discovery tab contains two sections, Target Portals and isns Servers. (isns Servers are described in another document.) Dell Compellent front-end ports are added as Target Portals. 3. Click on Add. If you are using Virtual Ports, enter the IP Address of the Control Port. If you are using Legacy Mode, enter the first Primary port IP Address. Do not enter Reserve ports. Continue until all front-end ports have been added. Figure 12: Configure Discovery Targets 4. Click on the Targets tab. In this example there are two targets. For MPIO to function correctly, each of the NIC cards must be logged in to each target, thus providing multiple connections to that specific target. 5. Select the first target and click Log On. 6. Check Automatically Restore to reconnect after a reboot. 7. Check Enable multi-path. 8. Click Advanced. October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 16

21 The advanced options window is where you select each NIC card to connect to the target. This log-on sequence must be done for each IP address that communicates with the frontend port. In this example, it entered two times for each target. The following steps will make a connection for each. 9. Select Microsoft iscsi Initiator from the Local adapter drop-down box. 10. Select the first IP address from the Source IP. 11. Select the Target Portal. 12. Select the necessary checkboxes for Data Digest and Header Digest. 13. Enter any Chap login information and click OK. 14. Select the same target and click Log On again. 15. Repeat steps 1-6 for each Source IP. 16. Select each additional Target and repeat steps 1-7. Figure 13: Configure Multiple Logons for Each Target Portal In this example, there are two targets and two source IP addresses. Each IP address is logged in to each target, creating four separate connections to the controller. October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 17

22 To verify: 1. Open the Dell Compellent System Manager. Create a server (if it hasn't already been done). 2. Click on the server in the tree view. 3. Click on the Connectivity tab. The connectivity window shows the IQN of the server and associated controller ports (target IP Addresses) that the server can see. Figure 14: System Manager iscsi Connectivity As can be seen in Figure 14, the two Dell Compellent ports see each of the server IP addresses as being connected ( and ). The iscsi Initiator is another method of verification: 1. From the Targets tab in the iscsi Initiator, select each of the targets. 2. Click on Details. There are two connections for each of the targets. 3. Click on Connections to verify that each connection is using a different source IP address. Figure 15: iscsi Initiator Connectivity Verification October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 18

23 4.6 Configuring Microsoft iscsi DSM At this point the server and the Dell Compellent Storage Center are connected and the connectivity has been verified. The next step is to use the Microsoft iscsi DSM to configure the default load balance policy for any new volumes that are mapped to the server. To configure the default MPIO policy: 1. Open the iscsi Initiator. 2. Click on the Targets tab. 3. Select each target and click on Details. Within the details section, there are two or more Identifiers. 4. Select each one and click on Connections. 5. Using the drop down menu, select an appropriate load balance policy for that connection, and click Apply. Note that this must be done for each connection. Figure 16: Default Load Balance Policy October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 19

24 To configure the MPIO policy for pre-existing volumes: 1. Open the iscsi Initiator. Click on Targets. 2. Select each of the targets. 3. Click Details. 4. Click Devices. 5. For each device, click Advanced. The Advanced window appears. 6. Click MPIO. 7. Select the appropriate policy for each volume. 8. Click Apply. Figure 17: Change Policy for Existing Volumes The Microsoft iscsi DSM offers three additional policies that the Dell Compellent DSM does not. Least Queue Depth: The DSM routes IO to the path with the least number of outstanding requests. Weighted Paths: A weight is assigned to each path. The weight indicates the relative priority of a given path. The larger the number the lower the priority. The DSM chooses the path with least weight. Least Blocks: The DSM routes requests to the processing path with the least number of pending IO blocks. In conclusion, there are two methods for handling MPIO in the Windows Server 2003 operating system. If you are using multiple protocols on the server, you must use the Dell Compellent Multipath Manager Software. However if iscsi is the only transport, the Microsoft iscsi DSM is a valid choice. Note: Remember that you cannot use both DSMs on the same server or there will be issues with the MPIO stack. October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 20

25 5 Using MPIO on Windows Server 2008 and 2008 R2 Windows Server 2008 and 2008 R2 have a built in Microsoft DSM out of the box that manages all aspects of failover and load balancing. Dell Compellent uses this DSM because it provides all required functionality for our customers. This also simplifies implementation, as there is no other software piece to install and maintain in the infrastructure. The built-in DSM for Windows Server 2008 and above can manage both iscsi and FC volumes. Note that the process for mapping volumes and creating servers is identical to the 2003 section described in Configuring Servers. It will not be covered again. The remaining sections cover Windows Server 2008 and 2008 R2 configuration options. October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 21

26 5.1 Installing the Microsoft MPIO DSM For Windows 2008 and above, the process of installing and configuring the Microsoft MPIO DSM has been streamlined. A new configuration tool, the Server Manager, provides a single interface for installing Features and Roles onto the server. To access Server Manager click on Start Administrative Tools Server Manager or click on the icon in the toolbar. There are currently two available options for installing the DSM: the Server Manager GUI or the servermanagercmd CLI Server Manager GUI To install using the GUI on 2008 and 2008 R2: 1. Open Server Manager. 2. In the tree view, click on Features. 3. Check MPIO. 4. Click Next. 5. Click Install. Once the feature has been installed click Yes, if prompted, to allow the reboot Server Manager CLI (2008 and 2008 R2 only) To install using the CLI, open an elevated command prompt. Enter:Servermanagercmd - install "Multipath-IO" To install MPIO on server core: Windows Server 2008: At the command prompt, type start ocsetup MultipathIo Window Server 2008 R2: At the command prompt, type DISM /online /enable-feature:multipathio Note: For server core installation, the above commands are case sensitive and must be run before you can use the MPCLAIM command. At this point the Microsoft MPIO DSM has been installed but not configured. You must associate Dell Compellent volumes with the DSM so that it can manage MPIO characteristics. The Microsoft DSM manages all Fibre Channel and iscsi volumes presented by the Dell Compellent Storage Center. You can choose either or both of these transports. You can also use the built-in iscsi initiator or an iscsi HBA; management of the iscsi Multipath IO is the same. The iscsi initiator provides all necessary performance and stability. However if you choose to use an HBA, it is still supported and available from Dell Compellent. October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 22

27 5.2 Associating Dell Compellent volumes with the DSM In the following section we will consider how to associate the DSM with Dell Compellent volumes and how to setup and configure the DSM based on the failover and load balancing policies of an organization. This section assumes that servers were created in the Dell Compellent System Manager and that at least one volume was mapped to the server via FC or iscsi in an MPIO based configuration. To associate the DSM with Dell Compellent volumes: 1. Open the MPIO control panel by clicking Start Administrative Tools MPIO. 2. Once opened click on Discover Multi-Paths. 3. Under Others, COMPELNTCompellent Vol appears. Note: If COMPELNTCompellent Vol does not appear, rescan disk devices in Disk Management. Click on COMPELNTCompellent Vol. Click Add. This can take a minute. Disk Management prompts you to reboot the server. Accept the prompt and allow the reboot. This one-time reboot sets up the associations. Another option for providing associations is the MPCLAIM CLI command. Open an elevated command prompt and type the following: mpclaim.exe -r -i -d "COMPELNTCompellent Vol" This command provides the same result as the Control Panel version. It associates a Dell Compellent volume and then restarts the server. To bypass the reboot option, for rebooting later, use the -n option rather than the -r option. Once the server reboots, use the Disk Management control panel to verify that everything is correct. There should only be one listing for the volumes in disk management. October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 23

28 5.3 Setting the default load balance policy Once volumes are associated, specify the default load balance policy and change any existing volumes to use the new policy. There are some slight differences between Windows 2008 and Windows 2008 R Windows Server 2008 default load balance policy By default in Windows Server 2008, the Dell Compellent volumes have a default load balance policy of Failover Only because a Storage Center is not an ALUA device. Unfortunately in the 2008 product there is no way to change the default policy. Therefore it is imperative that the policy is changed to reflect the best practices of an organization each time a volume is mapped to the server. The same procedure is used to change the policy on a per-volume basis with both Windows 2008 and Windows 2008 R Windows Server 2008 R2 default load balance policy As of the 2008 R2 release, a Storage Center is designated as a Round Robin device by default. However, R2 provides a method for changing the default policy system-wide as well as on a per-volume basis. To change the default load balance policy in 2008 R2 and 2012, use the MPCLAIM CLI command as follows: mpclaim.exe -L -M <0-7> -d "COMPELNTCompellent Vol" <0-7> refers to the desired load balance policy as shown in Table 1: Table 1: Windows 2008 R2 Load Balance Policy October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 24

29 For example, to change all Dell Compellent volumes to a Failover Only policy, use the following command: mpclaim.exe -L -M 1 -d "COMPELNTCompellent Vol" 5.4 Per-volume load balance settings Now that you set the default policy, you must understand how to change the policy on a per-volume basis. Some organizations may require a different policy based on the type of application or service provided. Use Disk Management in 2008 and 2008 R2 or through the MPCLAIM utility in 2008 R2 to change the per-volume policy. To change the policy in Disk Management: 1. Click Start Administrative Tools Server Manager. 2. In the tree view, click on Storage Disk Management. Figure 18: Disk Management 3. Right-click on the Disk number column for the disk. Select Properties. 4. Select the MPIO tab. October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 25

30 Figure 19: MPIO Settings Tab 5. From the drop-down box, select the appropriate MPIO policy for the volume. Refer to page 24 for a listing of the available policies and their intended functions Using MPCLAIM in 2008 R2 Windows Server 2008 R2 and 2012 provide an enhanced MPCLAIM utility that allows the policy to be changed on a per-volume basis much like Disk Management. The command is similar to setting the default policy for all volumes; however in this case the Administrator chooses which volume to set. List of all MPIO volumes on the system with the mpclaim command: mpclaim.exe -s d Figure 20: List disks with MPCLAIM Figure 20 shows that the current policy for Disk 0 is RR or Round Robin. Use the mpclaim.exe command to change the policy for this disk. mpclaim.exe -L -M 1 -d 0 Refer to the Microsoft TechNet site for the full MPCLAIM reference guide. October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 26

31 6 Using MPIO on Windows Server 2012 MPIO on Windows Server 2012 functions in the same way as on 2008 R2. However, Server 2012 introduces the MPIO module in PowerShell. The MPIO module is a powerful alternative to using the MPCLAIM command. Although the MPCLAIM command is included in Server 2012, Microsoft recommends using the MPIO module in PowerShell. This chapter will focus on using the GUI and PowerShell to install and configure MPIO. Note: On Server Core installations, please follow the instructions for PowerShell. PowerShell can be accessed on a Server Core installation by typing in powershell <enter> at the command prompt. Also new to Server 2012 is ability to use heterogeneous HBA types with MPIO. In previous versions of Windows Server, it was a requirement to use HBA s of the same model. Like Windows Server 2008 and 2008 R2, Windows Server 2012 contains a built-in Microsoft DSM out of the box that manages all aspects of failover and load balancing. 6.1 Installing the Microsoft MPIO Feature The MPIO DSM can be installed on Server 2012 either through the GUI or through the MPIO module in PowerShell Server Manager GUI 1. Open Server Manager. Figure 21: Server Manager 2. From the Dashboard, click on Add roles and features. October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 27

32 Figure 22: Add Roles and Features 3. When the Add Roles and Features Wizard window opens, click Next on the Before you Begin screen. 4. Select Role-based or feature-based installation and click Next. Figure 23: Role-based or feature-based installation 5. Choose the local server from the Select destination server screen and click Next. 6. Click Next on the Select server roles screen (do not select any roles to install). 7. Check Multipath I/O October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 28

33 Figure 24: Select Multipath I/O 8. Click Next. 9. Check the box to Restart the destination server automatically if required. 10. Click Install. 11. Click Close when finished PowerShell 1. Open an elevated PowerShell window 2. At the PowerShell Prompt, type in the following command: a. Enable-WindowsOptionalFeature online FeatureName MultiPathIO <enter> Figure 25: Enabling MPIO in PowerShell October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 29

34 6.2 Associating Dell Compellent volumes with the In-box DSM Now that the DSM has been installed, you must associate Dell Compellent volumes with the DSM so that the DSM can manage MPIO characteristics. On Windows Server 2012, Dell Compellent volumes can be associated with the DSM through the use of either the MPIO Control Panel, or through PowerShell. Note: Once the DSM is associated with Dell Compellent volumes, Windows will automatically claim all Fibre Channel and iscsi volumes presented from Storage Center and apply default MPIO settings to those volumes Using the MPIO Control Panel 1. Open the MPIO Control Panel through Server Manager, by clicking on Tools, then MPIO a. The MPIO Control Panel can also be accessed through the Control Panel Figure 26: MPIO Control Panel 2. Click on the Discover Multi-Paths tab 3. Under Others, you should see COMPELNTCompellent Vol October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 30

35 Figure 27: Discover Multi-Paths 4. Highlight COMPLENTCompellent Vol, and click Add 5. Click Yes on the Reboot Required window. Figure 28: Reboot Required 6. Once the server has rebooted, open up the MPIO Control Panel and verify that COMPELNTCompellent Vol is listed under Devices on the MPIO Devices tab. October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 31

36 Figure 29: MPIO Device Listing 7. Click OK to close the window Using PowerShell 1. Open an elevated PowerShell window a. On Server Core installations, type in powershell <enter> at the command prompt 2. At the PowerShell prompt type in: a. New-MSDSMSupportedHW VendorID COMPELNT ProductID Compellent Vol <enter> Figure 30: Adding Compellent to DSM 3. Dell Compellent is now supported through the Microsoft DSM. The next step is to claim all available Dell Compellent volumes to be used by MPIO. To do so, type in the following: a. Update-MPIOClaimedHW Confirm:$false Figure 31: Claiming Available Volumes 4. Restart the server by typing in the following: a. shutdown r t 0 <enter> October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 32

37 6.3 Setting the default load-balancing policy Like Server 2008 R2, the default load balancing policy on Server 2012 is Round Robin. However, the default load balancing policy can be changed system-wide or on a per-volume basis. Storage Center supports the Round Robin and Failover Only load-balancing policies on Server To change the default load balancing policy to Failover Only, open an elevated PowerShell window, and type in the following command: Set-MSDSMGlobalDefaultLoadBalancePolicy Policy FOO <enter> Figure 32: Set default load balance policy to Failover Only To change the default load balancing back to Round Robin, type in the following command: Set-MSDSMGlobalDefaultLoadBalancePolicy Policy RR <enter> Figure 33: Set default load balance policy to Round Robin To verify the default load balance policy, type in the following command: Get-MSDSMGlobalDefaultLoad BalancePolicy <enter> If the default policy is set to Round Robin, the result will read RR : Figure 34: Round Robin default load balance policy If the default policy is set to the Failover Only, the result will read FOO : Figure 35: Failover Only default load balance policy October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 33

38 6.4 Per-volume load balance settings Changing load balance settings on specific volumes can be done through the Disk Management GUI, or from PowerShell Using the Disk Management GUI: 1. Click Start Administrative Tools Computer Management. 2. In the tree view, click on Storage Disk Management. Figure 36: Disk Management 3. Right-click on the Disk number column for the disk. Select Properties. 4. Select the MPIO tab. Figure 37: MPIO Properties October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 34

39 5. From the drop-down box, select the appropriate MPIO policy (Failover Only or Round Robin) for the volume Using PowerShell: The PowerShell MPIO module doesn t include any cmdlets that can change the default load balancing policy on a specific volume. Like in Server 2008 R2, the MPCLAIM command must be used to make changes to specific volumes. Note: You cannot change the load balancing policy from Round Robin to Failover Only using the MPCLAIM command. You can only switch from Failover Only to Round Robin. To change the default load balancing policy on a single volume, open an elevated command prompt or PowerShell window (commands will work in both): To list all MPIO volumes on the system type in the following command: mpclaim s -d Figure 38: Listing MPIO volumes Figure 38 shows that the load balancing policy (LB Policy) is set to Round Robin for all 3 volumes. The syntax to change the load balancing policy on a specific volume is as follows: mpclaim l d <disk #> <0-7> <0-7> refers to the desired load balance policy in the following table: October 2012 (version 1.3)Dell Compellent Storage Center Microsoft Multipath IO (MPIO) Best Practices 35