Dell EMC SC Series Storage: Microsoft Multipath I/O

Transcription

1 Dell EMC SC Series Storage: Microsoft Multipath I/O Dell EMC Engineering June 2017 A Dell EMC Best Practices Guide

2 Revisions Date Description 10/11/2010 Initial release 10/21/2011 Corrected errors 11/29/2011 Additional content on Microsoft Windows Server Core 10/15/2012 Updated to include Windows Server 2012 content 5/29/2013 Updated to include Windows Server 2008 R2/2012 iscsi initiator setup and appendix listing recommended hotfixes and registry values 10/18/2013 Updated to include Windows Server 2012 R2 content 1/10/2014 Updated hotfix information 1/12/2015 Updated configuration recommendations 3/3/2015 Updated hotfix and configuration recommendations 4/17/2015 Added Dell SCv2000 series front-end SAS content 2/9/2016 Removed Windows Server 2003 content and updated hotfix recommendations 10/4/2016 Re-ordered document for clarity, added Windows Server 2016 and Nano Server content, and updated hotfix recommendations 1/20/2017 Updated configuration recommendations 6/30/2017 Updated hotfix info and configuration recommendations Acknowledgements Author: Kris Piepho The information in this publication is provided as is. Dell Inc. makes no representations or warranties of any kind with respect to the information in this publication, and specifically disclaims implied warranties of merchantability or fitness for a particular purpose. Use, copying, and distribution of any software described in this publication requires an applicable software license. Copyright Dell Inc. or its subsidiaries. All Rights Reserved. Dell, EMC, Dell EMC and other trademarks are trademarks of Dell Inc. or its subsidiaries. Other trademarks may be the property of their respective owners. Dell believes the information in this document is accurate as of its publication date. The information is subject to change without notice. 2 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

3 Table of contents Revisions... 2 Acknowledgements Preface Audience Introduction to Microsoft Multipath I/O SC Series storage connections Legacy port mode Virtual port mode Connectivity summary Configuring servers Fibre Channel iscsi SAS Automatic configuration of Fibre Channel and iscsi-connected servers Manual configuration of Fibre Channel and iscsi-connected servers Configuring a SAS server Automatic configuration Manual configuration Verifying Fibre Channel and iscsi connectivity Verifying SAS connectivity Restrict volume mapping paths (Fibre Channel and iscsi only) Restrict mapping paths on SAS-connected volumes Choose the I/O transport Installing MPIO Installing the MPIO feature on Windows Server 2008 R Server manager GUI Windows Server manager CLI To install MPIO on Server Core Installing the MPIO feature on Windows Server 2012 or later Server manager GUI PowerShell Configuring MPIO Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

4 5.1 Associating SC Series volumes with the Microsoft DSM Using the MPIO control panel Using PowerShell (Server 2012 or later) Using the MPCLAIM command Setting the default load balance policy Using the MPCLAIM command Using PowerShell (Server 2012 or later) Per-volume load balance settings Using the disk management GUI: Using the MPCLAIM command Configure a Windows Server 2008 R2 or later for iscsi MPIO Configuration MPIO on Windows Nano Server Enable MPIO Associating SC Series volumes with the Microsoft DSM Configuring iscsi A Windows Server single-path and MPIO configuration recommendations for SC Series storage A.1 Recommended updates and hotfixes for Windows Server 2008 R2 SP A.2 Recommended updates and hotfixes for Windows Server 2012 (non-r2 version) A.3 Recommended updates and hotfixes for Windows Server 2012 R A.4 Recommended updates and hotfixes for Windows Server A.5 Recommended registry settings for Windows Server A.6 iscsi initiator settings (single-path and MPIO) A.7 PowerShell script A.8 Resources B Additional resources B.1 Technical support and resources B.2 Related documentation Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

5 1 Preface This document provides an overview of Multipath I/O (MPIO) and introduces best practice guidelines for configuring MPIO on Microsoft Windows Server 2008 R2, 2012, 2012 R2, 2016, and Nano Server when using a Dell EMC SC Series array. 1.1 Audience This document was written for system administrators responsible for the setup and maintenance of Windows servers and associated storage. Readers should have a working knowledge of Windows Server and SC Series arrays. 5 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

6 2 Introduction to Microsoft Multipath I/O Microsoft MPIO is a framework that allows administrators to configure load balancing and failover processes for Fibre Channel, iscsi, and SAS connected storage devices. Load balancing can be configured to use up to 32 independent paths from the connected storage devices. SC Series arrays provide redundancy and failover with multiple controllers and RAID modes. However, servers still need a way to spread the I/O 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 Windows disk management. The MPIO framework uses Device Specific Modules (DSM) to allow path configuration. Microsoft provides a built-in generic Microsoft DSM (MSDSM) for Windows Server 2008 R2 and above. This MSDSM provides the MPIO functionality for Dell EMC storage customers. 2.1 SC Series storage connections Before reviewing server-specific MPIO functions, it is important to understand that various connection options are available with the SC Series arrays that allow multiple paths to be presented to the servers. The following section provides a quick overview and explains the differences between legacy port mode and virtual port mode. This overview does not take the place of the Storage Center Connectivity Guide available on the Dell SC Series Customer Portal (login required) Legacy port mode In legacy port mode, the front-end I/O ports are designated as either primary or reserve ports based on a fault domain. Primary and reserved ports allow I/O 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 as many I/O ports to enable multiple paths. Even more ports are required for a dual fabric. Figure 1 illustrates dual-fabric failover ports in legacy mode. Legacy mode example with Fibre Channel 6 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

7 As shown in Figure 1, a dual-controller SC Series array in legacy mode is connected to a Fibre Channel server with two fault domains. Fault domain 1 (shown in orange) is comprised of primary port P1 on controller A and reserved port R1 on controller B. Fault domain 2 (shown in green) is comprised of primary port P2 on controller B and reserved port R2 on controller A Virtual port mode Virtual port mode provides port and storage controller redundancy by connecting multiple active ports to each Fibre Channel or Ethernet switch. In virtual port mode, each physical port has a WWN (World Wide Name) and a virtual WWN. Servers target only the virtual WWNs. During normal conditions, all ports process I/O. If a port or storage controller failure occurs, a virtual WWN moves to another physical WWN in the same fault domain. When the failure is resolved and ports are rebalanced, the virtual port returns to the preferred physical port. Virtual port mode provides the following advantages over legacy mode: Increased connectivity: Because all ports are active, additional front-end bandwidth is available without sacrificing redundancy. Improved redundancy: - Fibre Channel: A Fibre Channel port can fail over to another Fibre Channel port in the same fault domain on the storage controller. - iscsi: In a single fault domain configuration, an iscsi port can fail over to the other iscsi port on the storage controller. In a two fault domain configuration, an iscsi port cannot fail over to the other iscsi port on the storage controller. Simplified iscsi configuration: Each fault domain has an iscsi control port that coordinates discovery of the iscsi ports in the domain. When a server targets the iscsi port IP address, it automatically discovers all ports in the fault domain Fibre Channel To use virtual ports for Fibre Channel, all Fibre Channel switches and host bus adapters (HBAs) must support N_Port ID Virtualization (NPIV). As shown in Figure 2, a dual-controller SC Series array in virtual port mode is connected to a Fibre Channel (FC) server with a single fault domain. All ports belong to a single fault domain because they are connected to the same FC switch. 7 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

8 Virtual ports example with Fibre Channel 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 only the control port in the iscsi initiator software needs to be assigned. These differences are covered below in the OS-specific sections SAS With select SC Series models that support SAS front-end connectivity, hosts or servers can access storage by connecting directly to SC Series SAS ports. In SAS virtual port mode, a volume is active on only one storage controller, but is visible to both storage controllers. Asymmetric Logical Unit Access (ALUA) controls the path that a server uses to access a volume. If a storage controller becomes unavailable, the volume becomes active on the other storage controller. The state of the paths on the available storage controller are set to Active/Optimized and the state of the paths on the other storage controller are set to Standby. When the storage controller becomes available again and the ports are rebalanced, the volume moves back to its preferred storage controller and the ALUA states are updated. If a SAS path becomes unavailable, the Active/Optimized volumes on that path become active on the other storage controller. The state of the failed path for those volumes is set to Standby and the state of the active path for those volumes is set to Active/Optimized. Note: Failover in SAS virtual port mode occurs within a single fault domain. Therefore, a server must have both connections in the same fault domain. For example, if a server is connected to SAS port two on one storage controller, it must be connected to SAS port two on the other storage controller. If a server is not cabled correctly when a storage controller or SAS path becomes unavailable, access to the volume is lost. 8 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

9 In the example shown in Figure 3, four fault domains are spread across both storage controllers. The storage controllers are connected to each host server using four SAS connections. If a storage controller port fails, the virtual port on the failed port moves to the other storage controller. Storage system connected to two host servers Connectivity summary There are two methods to enable multiple paths from an SC Series array: legacy port mode and virtual port mode. Virtual ports are preferred because they reduce the number of HBAs required, reducing cost and overhead. Note that virtual ports are enabled based on protocol: virtual ports can be enabled on Fibre Channel only, iscsi only, SAS only, both Fibre Channel and iscsi, or both SAS and iscsi. 9 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

10 3 Configuring servers Before configuring MPIO at the operating system level, first configure servers using Dell Storage Manager. The following example assumes a server has two or more of the following types of connections: Fibre Channel ports that are zoned to see the SC Series HBAs iscsi I/O ports that are in a VLAN that can see the SC Series HBAs SAS ports directly connected to the SC Series HBAs With Fibre Channel, the process is the same for virtual ports as it is for legacy ports. However, with legacy ports, the server cannot see reserve ports. iscsi virtual ports connect only to an SC Series control port. 3.1 Fibre Channel To create the server, properly zone the switches so that the server and controller ports are in the same zone. Boot the server into the card BIOS and scan the SCSI devices on each port. An alternate method is to preconfigure the WWNs of the HBAs in the System Manager. 3.2 iscsi As with Fibre Channel, an iscsi server can be created automatically or manually. For automatic configuration, enter the IP address of the SC Series 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 port mode, enter the IP address of the primary port. This is covered in more detail in the OS specific sections. 3.3 SAS To configure a Windows server directly connected to an SC Series unit by SAS, it is highly recommended to use the wizard. Configure this host to access an array in the Dell Storage Manager client. The wizard will automatically create a server object on the array, detect all available paths, and assign them to the server, as well as automatically apply recommended MPIO registry settings to the server. MPIO registry settings are discussed in detail in appendix A. A directly connected SAS server can also be created automatically or manually using a Dell Storage Manager client. Refer to section 3.6, Configuring a SAS server, for details on creating a SAS server. 10 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

11 3.4 Automatic configuration of Fibre Channel and iscsi-connected servers Once a server has scanned for devices or logged into the target, the SC Series array automatically recognizes the WWN/IQN. To configure a server: 1. Log in to the Dell Storage Manager client. 2. In the tree view, right-click 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 section 3.5, Manual configuration. Note: If the WWN or IQN is not listed, make sure that the Only Show Up Connections box is not checked. Create Server window 11 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

12 3.5 Manual configuration of Fibre Channel and iscsi-connected servers To manually configure an HBA: 1. In the Create Server wizard shown in Figure 4, click Manually Add HBA. 2. In the Select Transport Type window, choose Fibre Channel or iscsi. 3. Enter the WWN or iscsi name, and click Continue. Repeat steps 1-3 for every WWN or iscsi HBA to be associated with the server. 4. Once all of the HBAs are added, check the appropriate HBA and continue the wizard. Note: The new HBA appears with a white X in a red circle. Once the server is connected the warning state is removed. Manually defined HBA 3.6 Configuring a SAS server Automatic configuration To configure a server: 1. Log in to the SC Series array using the Dell Storage Manager client. 2. Select the Storage tab. 3. In the tree view, right-click Servers. 4. From the shortcut menu, select Create Server. 12 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

13 5. In the Create Server window, assign the server a name. 6. Select a server folder (if applicable). 7. Select an operating system (Windows Server 2008 MPIO or Windows Server 2012 MPIO only). 8. Select the available HBA(s) and click OK. 13 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

14 3.6.2 Manual configuration To manually configure a SAS HBA: 1. In the Create Server window, click Manually Add HBA. 2. In the Manually Add HBA window, enter the SAS HBA WWN. 3. Select SAS in the HBA Port Type drop-down menu and click OK. 4. Repeat steps 1-3 to associate more SAS HBAs with the server. 5. Once all HBAs are added, check the appropriate HBA and continue the wizard. Note: The new HBA appears with a white X in a red circle. Once the server is connected the warning state is removed. 14 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

15 3.7 Verifying Fibre Channel and iscsi connectivity To ensure correct connectivity: 1. Login to the Dell Storage Manager client. 2. In the tree view, select a server. 3. Click Connectivity. This window shows all paths available to the server based on the HBA and controller ports. Fibre Channel connectivity The connectivity tab displays the HBAs that are defined for the server object and the SC Series array HBAs/control ports the server HBAs are attached to. In the example shown in Figure 6, there are a total of eight possible paths because each of the two Fibre Channel HBA ports on the server can see four Fibre Channel HBA ports assigned to each fault domain. 15 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

16 iscsi connectivity In the example shown in Figure 7, there are a total of four possible paths because each of the two iscsi NICs on the server can see two iscsi control ports assigned to each fault domain. 3.8 Verifying SAS connectivity To ensure correct SAS connectivity: 1. Log in to the Dell Storage Manager client. 2. Click the Storage tab. 3. In the tree view, select a server. 4. Click Connectivity. This view will show all defined SAS HBAs, and paths to ports on the top and bottom controllers. 16 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

17 SAS connectivity 3.9 Restrict volume mapping paths (Fibre Channel and iscsi only) An SC Series volume is mapped to all available paths unless the advanced mapping button is used to restrict mapping paths to FC only, iscsi only, or specified HBA ports and controller ports. To restrict mapping paths: 1. Log in to the Dell Storage Manager client. 2. In the tree view, right-click a volume and 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 Options. 5. Under Restrict Mapping Paths, uncheck the box to Map to All Available Ports. 6. Select one of the following: - Map using specific server ports (check the specific server ports) - Limit ports by transport type (select a transport from the drop-down menu) Note: The option to limit ports by transport type is only available on systems that have more than one transport type available, such as both Fibre Channel and iscsi. Note: Using mixed transports concurrently on the same Windows server host is not supported with Server 2012 R2 and newer. With Server 2012 R2 and newer, when a LUN is presented to the host that is using multiple transports such as Fibre Channel and iscsi, the host will default to one transport or the other (typically Fibre Channel is chosen by the host) and ignore the other transport. If all paths for one type of transport go down, the host may not send data using the other transport without a disk re-scan. This is default Windows Server behavior. 17 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

18 Map using specific server ports Limit ports by transport type Assuming the default mapping wizard is used and paths are not restricted, a volume is mapped to all available paths, creating multiple I/O paths from the server to the volume. To view the mapped paths, select a volume in the tree view and click the Mappings tab. 18 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

19 Figure 11 shows MPIO 500GB_Volume mapped to the server with four FC ports and two iscsi ports. Volume mapping tab 3.10 Restrict mapping paths on SAS-connected volumes To restrict mapping paths on SAS-connected volumes: 1. Log in to Dell Storage Manager client. 2. Click the Storage tab. 3. In the tree view, right-click a volume and select Map Volume to Server. The Map Volume to Server wizard appears. 4. Select a server and click Next. 5. Select Advanced Options. 6. Under Restrict Mapping Paths, uncheck Map to All Available Server Ports. 7. Select the HBA(s) to use when mapping this volume. 8. Click Finish to map the volume to the selected server. 19 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

20 Restrict mapping paths To view the mapped paths, select a volume in the tree view and click the Mappings tab. Figure 13 shows volume SAS MPIO Volume mapped to the server with all available SAS ports. Volume mappings tab 20 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

21 3.11 Choose the I/O transport Dell EMC offers the following I/O transports: 8GB, 16GB, and 32GB Fibre Channel (SCv9000 series only), 10GB iscsi, and 12GB SAS. Choosing an I/O transport method largely depends on the current infrastructure in an organization and its future plans. Fibre Channel offers better performance than iscsi, but requires a dedicated infrastructure. For a converged fabric, iscsi is the best option because it can utilize existing networking infrastructure. For smaller organizations without existing infrastructure or environments where directly-attached storage is preferred, SAS offers excellent performance for a simple, cost-effective solution. It is recommended that there are multiple front-end controller paths to the servers and that the servers have multiple connections to the controller. Note: Windows Server 2012 or later includes the ability to use heterogeneous HBA types with MPIO. In previous versions of Windows Server, it was a requirement to use HBAs of the same model. 21 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

22 4 Installing MPIO Beginning with Windows Server 2008, Microsoft includes a built-in DSM that manages all aspects of failover and load balancing. Dell EMC storage uses this DSM because it provides all the functionality required for our customers. This also simplifies implementation, as it eliminates the need to install and maintain another piece of software in the environment. The Microsoft DSM is not functional on Windows Server until the MPIO feature is installed. The Microsoft DSM for Windows Server can manage iscsi, FC, and SAS volumes. Note: MPIO is required for directly-connected SAS volumes and is only supported on Windows Server 2008 R2 or later. Please refer to appendix A in this document for important Windows Server 2008 R2 MPIO configuration recommendations. 4.1 Installing the MPIO feature on Windows Server 2008 R2 On Windows Server 2008 R2, the MPIO feature can be installed using Server Manager. Server Manager offers two options for installing the MPIO feature: the Server Manager graphical unit interface (GUI) or the servermanagercmd command line interface (CLI). To access Server Manager, click Start > Control Panel > Administrative Tools > Server Manager, or click the Server Manager icon in the taskbar Server manager GUI To install using the Server Manager GUI: 1. Open Server Manager. 2. In the tree view, click Features. 3. Under Features Summary, click Add Features. 4. Check MPIO and click Next. 5. Click Install. Once the feature has been installed click Yes, if prompted, to allow the reboot Windows Server manager CLI To install using the CLI, open a command prompt with elevated (administrator) privileges and type: Servermanagercmd -install "Multipath-IO" To install MPIO on Server Core For a Window Server 2008 R2 Core installation, open a command prompt and type: DISM /online /enable-feature:multipathio Note: For Windows Server Core installations, the prior commands are case sensitive. 22 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

23 4.2 Installing the MPIO feature on Windows Server 2012 or later The MPIO feature can be installed on Windows Server 2012 or later either through the Server Manager GUI or through the MPIO module in Microsoft PowerShell. Note: On Windows Server 2012 and 2012 R2 Core installations, follow the instructions for PowerShell. To access PowerShell on a Server Core installation, type powershell and press Enter at the command prompt Server manager GUI 1. Open Server Manager. 2. From the Dashboard, click Add roles and features. 3. When the Add Roles and Features Wizard window opens, click Next. 23 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

24 4. Select Role-based or feature-based installation and click Next. 5. Choose the local server, and click Next. 6. Without selecting a role to install, click Next on the Select server roles screen. 7. Check Multipath I/O and click Next. 8. Check the box to restart the destination server automatically if required. 9. Click Install. 10. Click Close when finished. 24 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

25 4.2.2 PowerShell 1. Open a PowerShell window with elevated (administrator) privileges. 2. At the PowerShell prompt, enter the following command: Enable-WindowsOptionalFeature Online FeatureName MultiPathIO Note: When installing the MPIO feature using PowerShell on Windows Server 2016, the user is prompted to restart the server to complete installation: If possible, it is recommended to reboot the server immediately. To bypass the reboot prompt, specify the -NoRestart option at the end of the PowerShell command: 25 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

26 5 Configuring MPIO This section describes how to associate the Microsoft DSM with SC Series volumes and how to set up and configure the Microsoft DSM based on the failover and load balancing policies of an organization. These instructions assume that servers have been created in Dell Storage Manager and that at least one volume is mapped to the server using FC, iscsi, or SAS with MPIO enabled. Note: When the MPIO configuration is complete, refer to appendix A for important MPIO-specific hotfix and registry settings. 5.1 Associating SC Series volumes with the Microsoft DSM At this point, the Microsoft MPIO DSM has been installed but not configured. SC Series volumes must be associated with the DSM so that it can manage MPIO characteristics. The Microsoft DSM manages all Fibre Channel, iscsi, and SAS volumes presented. The built-in iscsi initiator or an iscsi HBA can also be used with the same management for the iscsi Multipath I/O. Note: The software iscsi initiator included in Windows Server 2008 R2 or later provides the necessary performance and stability required for iscsi connections to an SC Series array. However, Dell supports the use of an iscsi HBA Using the MPIO control panel To associate the SC Series volumes with the DSM through the use of the MPIO Control Panel, follow these steps: 1. Open the MPIO control panel by clicking Start > Administrative Tools > MPIO. 2. Click the Discover Multi-Paths tab. 26 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

27 3. Under Others, COMPELNTCompellent Vol should be displayed. Note: If COMPELNTCompellent Vol does not appear, rescan disk devices in Disk Management. 4. Highlight COMPELNTCompellent Vol, and click Add. 5. Click Yes on the Reboot Required window. 6. Once the server has rebooted, open the MPIO Control Panel and verify that COMPELNTCompellent Vol is listed under Devices on the MPIO Devices tab. 7. Click OK to close the window. 27 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

28 5.1.2 Using PowerShell (Server 2012 or later) Windows Server 2012 or later includes the MPIO module in Windows PowerShell. The MPIO module is a powerful alternative to using the mpclaim command. Although the mpclaim command is also included in Windows Server 2012 and above, Microsoft recommends using the MPIO module in PowerShell. To associate the SC Series volumes with the DSM through the use of PowerShell, follow these steps. 1. Open a PowerShell window with elevated (administrator) privileges. a. On Server Core installations, type powershell and then press [Enter] at the command prompt. 2. At the PowerShell prompt type: New-MSDSMSupportedHW VendorID "COMPELNT" ProductID "Compellent Vol" Note: On Windows Server 2016, if the server has not been rebooted after the MPIO feature installation, the prior command will fail. In this case, reboot the server and re-run the command to associate SC Series volumes with the DSM. 3. Now that SC Series storage is supported through the Microsoft DSM, claim all available SC volumes to be used by MPIO by typing: Update-MPIOClaimedHW Confirm:$false 4. Restart the server by typing: shutdown r t 0 [Enter] Using the MPCLAIM command The MPCLAIM CLI command can also be used to associate SC Series volumes with the Microsoft DSM. Open a command prompt with elevated (administrator) privileges and type the following: mpclaim.exe -r -i -d "COMPELNTCompellent Vol" This command provides the same result as the MPIO Control Panel and PowerShell options. It associates SC Series volumes and then restarts the server. To bypass the reboot option (if rebooting later is desired), use -n in place of -r. Once the server reboots, use Disk Management to verify that the configuration is correct. There should only be one instance of each SAN volume listed in Disk Management. 28 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

29 5.2 Setting the default load balance policy Once the SC Series volumes are associated with the Microsoft DSM, specify the default load balance policy and change any existing volumes to use the new policy. The default load balancing policy can be changed system-wide or on a per-volume basis. For SCOS versions 6.5 and earlier, the default load balance policy for SC Series volumes is round robin. Note: Failover only and round robin are the only MPIO load balancing policies supported on SCOS versions 6.5 and earlier. For SCOS version 6.6 and later, Fibre Channel and iscsi-connected volumes (both single and multi-path) will default to round robin. SAS-connected volumes default to round robin with subset. SC Series volumes mapped with both Fibre Channel and iscsi transports will default to round robin. Volumes mapped with both SAS and iscsi will default to round robin with subset. Note that on SCOS 6.6 and later: Failover only, round robin, and least queue depth are the only MPIO load balancing policies supported on Fibre Channel and iscsi volumes. SC series SAS-connected volumes support the following MPIO load balancing policies: round robin with subset, least queue depth and weighted paths Using the MPCLAIM command To use the MPCLAIM command to change the default load balance policy, open a command prompt with elevated (administrator) privileges and type the following: mpclaim.exe -L -M <0-7> -d "COMPELNTCompellent Vol" <0-7> refers to the desired load balance policy as shown in Table 1. Parameter MPCLAIM load balancing options Definition 0 Clear the policy 1 Failover only 2 Round robin 3 Round robin with subset 4 Least queue depth 5 Weighted paths 6 Least blocks 7 Vendor specific 29 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

30 For example, to change all SC Series volumes to a failover only policy, use the following command: mpclaim.exe -L -M 1 -d "COMPELNTCompellent Vol" Using PowerShell (Server 2012 or later) The MPIO module in PowerShell provides the ability to set the default load balance policy to round robin (RR), failover only (FOO), least blocks (LB), or least queue depth (LQD). To change the default load balancing policy to failover only, open a PowerShell window with elevated (administrator) privileges and type: Set-MSDSMGlobalDefaultLoadBalancePolicy Policy "FOO" To change the default load balancing back to round robin, type: Set-MSDSMGlobalDefaultLoadBalancePolicy Policy "RR" To verify the default load balance policy, type: Get-MSDSMGlobalDefaultLoadBalancePolicy If the default policy is set to round robin, the result will return RR: If the default policy is set to failover only, the result will return FOO: 5.3 Per-volume load balance settings Now that the default policy is set, it is important to 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 or the MPCLAIM utility to change the per-volume policy. Note: The PowerShell MPIO module does not include cmdlets that can change the default load balancing policy on a specific volume. 30 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

31 5.3.1 Using the disk management GUI: 1. Click Start > Administrative Tools > Computer Management. 2. In the tree view, click Storage > Disk Management. 3. Right-click the desired disk number and select Properties. 4. Select the MPIO tab. 5. From the drop-down menu, select the appropriate MPIO policy for the volume. 31 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

32 5.3.2 Using the MPCLAIM command Note: The load balancing policy cannot be changed from round robin to failover only using the MPCLAIM command. MPCLAIM only supports switching from failover only to round robin. To change the default load balancing policy on a single volume, open a command prompt or PowerShell window with elevated (administrator) privileges (commands will work in both). To list all MPIO volumes on the system, type: mpclaim s d Figure 14 shows that the load balancing policy (LB Policy) is set to RR (round robin) for disks 0 and 1. Listing MPIO volumes The syntax to change the load balancing policy on a specific volume is: mpclaim l d <disk #> <0-7> Refer to Table 1 for load balancing policies and the associated numbers for the mpclaim command. To change the load balancing policy of MPIO disk 2 to round robin, type: mpclaim l d 2 2 Verify the new settings by typing: mpclaim s d To verify MPIO settings, refer to Microsoft TechNet for the full MPCLAIM reference guide. 32 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

33 6 Configure a Windows Server 2008 R2 or later for iscsi MPIO Windows Server 2008 R2 or later supports MPIO with the iscsi software initiator. iscsi initiator software is provided natively by the Windows Server OS. Note: For instructions on how to configure Windows Nano Server for iscsi MPIO, refer to section 7, MPIO on Windows Nano Server. The iscsi quick connect feature works well for single iscsi path connectivity. Configuring iscsi to use MPIO requires a few more steps, but is still easy to configure. Figure 15 represents a dual-controller SC Series array that is configured with virtual front-end ports with two fault domains. Two physical iscsi ports (one from each controller) are grouped logically as a virtual domain that is assigned a virtual iscsi IP address. Each virtual domain physical port is connected to two separate iscsi switches to ensure full path redundancy to the dual iscsi NICs on the server. iscsi virtual ports and domains 33 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

34 6.1 Configuration The environment created for this configuration is illustrated in Figure 15 and includes: Windows Server 2008 R2 or later Two dedicated NIC ports (one for each fault domain) on the server for iscsi communications An SC Series array with dual controllers configured with virtual front-end iscsi ports and two virtual fault domains The MPIO feature installed on the server To configure the server for iscsi MPIO, complete the following steps. 1. Configure two physical NIC ports on the server to use iscsi. 2. Configure one NIC (including the necessary cabling and switching configurations) to access one virtual iscsi domain, and configure the second NIC to access the other virtual iscsi domain. 3. In the example shown in Figure 15, the server NICs are assigned with IPs of (for fault domain 100), and (for fault domain 200). 4. Once configured, the server should be able to ping both of the virtual iscsi IP addresses associated with the two fault domains on the array. In this example, (fault domain 100) and (fault domain 200). 5. Log on to the Windows server and launch the iscsi initiator software. 6. Go to Start > Administrative Tools > iscsi Initiator. Note: If receiving a prompt to start the iscsi service, click Yes. 7. Select the Discovery tab, and click Discover Portal. 34 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

35 8. Enter the IP address of the first iscsi control port (in this example, the virtual iscsi IP address associated with the first fault domain on the array), and click Advanced. 9. From the Local adapter drop-down menu, select Microsoft iscsi Initiator. From the Initiator IP drop-down menu, select the local IP address of the server NIC that is to be associated with the first fault domain (fault domain 100). This example uses Initiator IP Click OK, and then OK again to return to the iscsi Initiator properties window. 11. Verify that the target IP address and adapter IP address are displayed in the Target portals section. 12. Repeat steps 1-11 to add the second target IP for the second virtual fault domain and the server second iscsi NIC (in this example, and ). 35 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

36 13. When completed, both pairs of iscsi initiators and targets are listed. 14. Select the Targets tab. This should be populated with the discovered iscsi target ports on the array. 15. Highlight the first target, and click Connect. 16. On the Connect To Target screen, verify that both Add this connection to the list of Favorite Targets and Enable multi-path are checked. 17. Click Advanced to display additional options. 36 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

37 18. Set Local adapter to Microsoft iscsi Initiator. 19. Select the correct IP addresses for the Target portal IP and Initiator IP from the drop-down menus. 20. Click OK, and then OK again to return to the iscsi Initiator properties window. 21. Repeat steps for each additional target listed. 22. When finished, all the targets show a Connected status. 23. Click OK to exit the iscsi Initiator Properties window. 37 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

38 7 MPIO on Windows Nano Server Nano Server is a new deployment option for Windows Server Nano Server is a headless, lightweight, more secure version of Windows Server that requires fewer updates and restarts. Nano Server includes PowerShell 5.1 Core Edition. PowerShell Core Edition was built to run on reduced footprint editions of Windows such as Nano Server, and contains fewer modules and cmdlets than the Desktop Edition, which is included with Windows Desktop and Core editions. Nano Server can be administered through a remote PowerShell connection, or by using GUI tools on a full Windows Server 2016 installation. All the commands in this section are issued through a remote PowerShell session (PSsession) to the Nano Server. For more information about Nano Server, refer to the Getting Started with Nano Server page on Microsoft TechNet. 7.1 Enable MPIO At the PowerShell prompt, enter the following command: Enable-WindowsOptionalFeature Online FeatureName "MultiPathIO" When prompted, answer Yes to restart Nano Server immediately, or No to restart the server later. After restarting Nano, re-establish a remote PowerShell connection to the Nano Server. To verify MPIO is enabled, type the following command: (Get-WindowsOptionalFeature Online FeatureName "MultiPathIO").State The command will return Enabled if the MPIO feature is working properly. 38 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

39 7.2 Associating SC Series volumes with the Microsoft DSM Unlike previous versions of Windows Server, Nano Server does not include the MPIO PowerShell module or the mpclaim command. A Microsoft-provided PowerShell script must be run on the Nano Server to associate SC Series volumes with the Microsoft DSM. The script and instructions for using it can be found on TechNet. Keep in mind that when running the MPIO claim script, the load-balance policy is chosen dynamically and cannot be modified. All Fibre Channel and iscsi-connected SC Series volumes will use round robin as the load balance policy. SAS-connected SC Series volumes will use round robin with subset as the default policy. By default, the script will configure the server to claim all volumes on all transports (FC, iscsi, and SAS). If desired, the script can be configured to claim volumes on a specific transport. A reboot is required when the script has completed running. 7.3 Configuring iscsi Nano Server includes a software iscsi initiator which is configured through PowerShell. The Nano Server iscsi initiator supports both single-path and multi-path connections to iscsi-connected SC Series volumes. For the examples that follow, the Nano Server will be configured to connect to a dual-controller SC Series array configured with two iscsi fault domains. The Nano Server has two dedicated NIC ports that will be used for iscsi traffic (one port for each SC Series fault domain). By default, the iscsi service is not running on a Nano Server. The service must be started, and the service must all be set to start automatically when the server starts. To start the iscsi service, type: Start-Service Name "MSiSCSI" To verify the iscsi service is running, type: Get-Service Name "MSiSCSI" The Status shows Running. 39 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

40 To set the iscsi server to automatic startup: 1. Type the following: Set-Service Name "MSiSCSI" StartupType "Automatic" 2. Establish a connection to the first SC Series iscsi fault domain. New-IscsiTargetPortal TargetPortalAddress "<fault domain 1 IP Address>" ` -InitiatorPortalAddress "<iscsi adapter 1 IP address>" ` -InitiatorInstanceName "ROOT\ISCSIPRT\0000_0" 3. Obtain a list of targets on the established portal. Get-IscsiTarget 40 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

41 4. Connect to each target listed, enabling multipath and making the connection persistent. Connect-IscsiTarget IsMultipathEnabled $true NodeAddress ` "<SC node address>" -InitiatorPortalAddress "<iscsi adapter 1 IP address>" ` -IsPersistent $true 5. Repeat this process for all the targets listed in Get-IscsiTarget: 41 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

42 6. When the targets are connected, use Get-IscsiTarget to view the IsConnected status as True for each node address. 7. View active iscsi connections. Get-IscsiConnection 8. Establish a connection to the second SC Series iscsi fault domain. New-IscsiTargetPortal TargetPortalAddress "<fault domain 2 IP Address>" ` -InitiatorAddress "<iscsi adapter 2 IP address>" ` -InitiatorInstanceName "ROOT\ISCSIPRT\0000_0" 42 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

43 9. Obtain a list of targets on the established portal to the second fault domain. Get-IscsiTarget 10. Connect to each target that is not connected to enable multipath and make the connection persistent. Connect-IscsiTarget IsMultipathEnabled $true NodeAddress ` "<SC node address>" -InitiatorPortalAddress "<iscsi adapter 2 IP address>" ` -IsPersistent $true 43 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

44 11. Repeat this process for any other non-connected targets listed in Get-IscsiTarget. 12. All items shown in Get-IscsiTarget should now show as connected: At this point iscsi connectivity between the Nano Server and SC Series array has been established. A server object can now be created on the SC Series array, allowing volumes to be mapped to the Nano Server using the iscsi transport method. For detailed instructions on how to create a server object on an SC Series array, refer to section 3, Configuring servers. 44 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

45 A Windows Server single-path and MPIO configuration recommendations for SC Series storage Note: The recommended updates and hotfixes in this section list the names (msdsm.sys, mpio.sys, storport.sys, and msiscsi.sys) and modified dates of storage-specific files that are loaded when the associated update or hotfix is applied. If a newer version of the file listed is already loaded on the server, the recommended update or hotfix does not need to be loaded. Note: In some cases, prerequisite updates must be installed on the server before the following hotfixes can be installed. Please read the prerequisite information for each applicable hotfix before proceeding. Note: Updates and hotfixes are listed in the order in which they should be installed. Note: The registry settings below should be made on all Windows Server hosts that use the Microsoft DSM to access LUNs on SC Series arrays in order to ensure proper behavior and performance. This includes hosts configured to use single-path and MPIO. Note: Using mixed transports concurrently on the same Windows Server host is not supported with Server 2012 R2 and newer. With Windows Server 2012 R2 and newer, when a LUN is presented to the host that is using multiple transports such as Fibre Channel and iscsi, the host will default to one transport or the other (typically Fibre Channel is chosen by the host over iscsi) and ignore the other transport. When configured to use multiple transports, if all paths for one type of transport go down, the host may not send data using the other transport without a disk re-scan. This is default Windows Server behavior. 45 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

46 A.1 Recommended updates and hotfixes for Windows Server 2008 R2 SP1 Recommended updates and hotfixes for Windows Server 2008 R2 SP1 KB number Title Link KB Convenience rollup update for Windows 7 SP1 and Windows Server 2008 R2 SP1 (mpio.sys, msdsm.sys, storport.sys, msiscsi.sys 3/25/16) A.2 Recommended updates and hotfixes for Windows Server 2012 (non-r2 version) Recommended updates and hotfixes for Windows Server 2012 (non-r2 version) KB number Title Link KB KB KB KB Windows-based MSDSM doesn t handle sense code 02/04/03 (LUN Not Ready Manual Intervention Required) (mpio.sys 9/24/2014) No host bus adapter is present error when querying SAS cable issues in Windows Server 2012 R2 or Windows Server 2012 (storport.sys 11/19/2014) Server may freeze during startup when ALUAcapable storage is used in Windows Server 2012 R2 or Windows Server 2012 (msdsm.sys - 5/6/2015) Data is corrupted after iscsi sessions or paths recover in Windows Server 2012 R2 or Windows Server 2012 (msiscsi.sys 11/9/2015) Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

47 A.3 Recommended updates and hotfixes for Windows Server 2012 R2 Recommended updates and hotfixes for Windows Server 2012 R2 KB Number Title Link KB KB KB KB System fails back to a host copy instead of an array copy or storages go down after LUN reset in Windows Server 2012 R2 (msdsm.sys 1/24/2016) October 2016 Preview of Monthly Quality Rollup for Windows 8.1 and Windows Server 2012 R2 (msiscsi.sys 9/9/2016) "0x000000D1" Stop error with update rollups on Windows Server 2012 R2 (mpio.sys 12/9/2016) iscsi disks are lost on upgrade for StorSimple appliances after update is installed on Windows Server 2012 R2 (storport.sys 12/9/2016) A.4 Recommended updates and hotfixes for Windows Server 2016 Microsoft publishes updates for Windows Server 2016 cumulatively. Any updates for storage-related files are included in the cumulative updates. Recommended updates and hotfixes for Windows Server 2016 KB Number Title Link KB Cumulative Update for Windows Server 2016 for x64-based Systems May 2017 (mpio.sys 4/27/2017, storport.sys 3/4/2017, msiscsi.sys 3/28/2017) 47 Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004

48 A.5 Recommended registry settings for Windows Server The recommend registry settings listed in this section can be applied using the registry editor (regedit.exe) or through PowerShell. The registry editor can be used on all versions of Windows Server Desktop (Server with a GUI). PowerShell is the only option available to change registry settings on Nano Server, but can also be used on all versions of Windows Server Desktop. Refer to section A.7 for a PowerShell script that will apply recommended registry settings to all versions of Windows Server and Nano Server. Note: Recommended registry settings apply to all versions of Windows Server unless directly specified. Setting name Recommended registry settings location: HKLM\SYSTEM\CurrentControlSet\Services\mpio\Parameters Description Default value Recommended value PDORemovePeriod PathRecoveryInterval This setting controls the number of seconds that the multipath pseudo-lun remains in system memory, even after losing all paths to the device. When this timer value is exceeded, pending I/O operations will be failed, and the failure is exposed to the application rather than attempting to continue to recover active paths. The maximum time allowed is MAXULONG (49,000 days). Represents the period after which PathRecovery is attempted. This setting is only used if it is not set to 0 and UseCustomPathRecoveryInterval is set to UseCustomPathRecoveryInterval If this key exists and is set to 1, it allows the use of PathRecoveryInterval. 0 1 PathVerifyEnabled This flag enables path verification by MPIO on all paths every N seconds (where N depends on the value set in PathVerificationPeriod). This Boolean function must be filled with either 0 (disable) or 1 (enable). By default, it is disabled Dell EMC SC Series Storage: Microsoft Multipath I/O CML1004