Dell™ Storage Solutions Guide for Microsoft® Hyper-V™ w w w. d e l l . c o m | s u p p o r t . d e l l .
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Contents Getting Started With Microsoft® Hyper-V™ Technology . 5 . . . . . . . . . . . 5 . . . . . . . 7 . 7 . . . . . . . . . . . . . . . . . . . . . . . 8 Understanding Hyper-V Architecture iSCSI Connections Within the Guest OS Storage Options for Virtual Machines (VMs) in Hyper-V Disk Type Disk Location . . . . . . . . . . . . . . . . . . . . Disk Interface . 13 . . . . . . . . 15 . . . . . . . . . . . . . 17 . . . . . . . . . . . . . . . . . . . . 18 . . . . . . . . . . . . . . .
Appendix A: Planning for iSCSI-Based Storage Area Networks (SAN) 38 Physical Server Hosting Hyper-V . iSCSI Network Switches . . . . . . . . . 38 . . . . . . . . . . . . . . 38 Appendix B: Preparing Storage for Your VMs . . . . . . 40 Preparing the Disk for Use as a Passthrough Disk . 40 Preparing the Disk for Storing VHDs or VM Files . . 41 . . . . . . . . . . . . . . . . . . 42 Appendix C: Glossary Appendix D: References . 4 Contents . . . . . . . . . . . . . . . .
Getting Started With Microsoft® Hyper-V™ Technology The Dell Storage Solutions Guide for Microsoft Hyper-V provides an overview of: • Storage options available in Hyper-V • How Dell-supported storage solutions fit into a Hyper-V Deployment • Best practices associated with solution deployment The solutions guidance provided in this guide is primarily focused on storage arrays based on their support for key virtualization features, such as high availability and virtual machine migration.
Figure 1. Hyper-V Architectural Overview Guest operating systems requires specialized drivers (VSCs) provided by Microsoft in order to access the VMBus. The drivers are specific to the type of device that is presented to the guest operating system through the VM configuration and are installed as a part of the Integration Services that are available for Hyper-V supported guest operating systems.
iSCSI Connections Within the Guest OS Hyper-V supports iSCSI connections initiated directly from within a guest operating system to an iSCSI storage array. In this configuration, an iSCSI software initiator within the guest OS is connected to an iSCSI storage array. The iSCSI connection and any iSCSI LUNs that are provisioned directly to the guest OS are not visible by the parent partition.
Disk Type Virtual Hard Disk A VHD is a file that resides on a formatted partition that the parent partition has access to (see Figure 2). When presented to a VM, this file appears to the guest OS as a hard disk with a set of raw blocks. The guest OS can utilize the VHD just as it would a physical disk. Figure 2.
Passthrough Disk A passthrough disk is a physical disk mapped directly to a VM (see Figure 3). To the parent partition, the disk is an offline state and direct read/write access to the disk is not available. I/O requests from the VM are passed through the parent partition to the disk. With the parent partition free from managing the disk, additional CPU cycles are provided for virtual machine processing.
• Hyper-V does not restrict VMs from selecting disks that have been made a clustered resource as a passthrough disk. If disks that have been made a clustered resource are selected as passthrough disks for other VMs, data may be inadvertently overwritten. Ensure that you select the appropriate disk during configuration.
Disk Location When determining VHD and/or passthrough disk location for VM(s), the following options are available: • Internal storage • External storage • SMB/CIFS Share Internal Storage Internal storage encompasses disks that reside within the server chassis. Internal disks can be presented directly to the server or they can be managed by a RAID controller to provide disk aggregation and fault tolerance.
Figure 4. Storage Array (Single Server Configuration) SMB/CIFS Share In addition to supporting a VHD on a disk managed by the parent partition, Hyper-V also supports VHDs on a SMB/CIFS share; however, the use of SMB/CIFS shares is beyond the scope of this document. For more information see the Microsoft Hyper-V documentation or the Dell High Availability Solutions Guide for Microsoft Hyper-V at www.dell.com/hyper-v. Disk Location Summary Table 2.
Type Advantages Disadvantages Storage array • Support for HA VMs and VM Quick Migration. • Provides additional storage capacity for the server. SMB/CIFS share • Support for HA VMs and • Does not support VM Quick Migration. passthrough disks. • Provides additional storage capacity for the server. • Relatively lower performance Disk Interface After the disk type and storage location have been determined, the next step is to determine what type of virtual storage controller the disk will reside on.
Figure 5. Disk Interface (With an Attached Fibre Channel Storage Array) Integration Services By default, a guest OS only supports emulated IDE devices. Emulated IDE devices typically require a large amount of processor overhead to handle the device emulation and do not utilize the high-speed VMBus. To utilize the VMBus and therefore increase I/O performance, Hyper-V supports synthetic SCSI devices and an enhanced mode for IDE devices through the installation of Integration Services within the guest OS.
• Windows Vista (x64) SP1 • Windows XP Professional (x86) SP2-SP3 • Windows XP Professional (x64) SP2 For a current list of guest operating systems that support synthetic SCSI devices, refer to the Hyper-V Planning and Deployment Guide available at www.microsoft.com/downloads. Disk Interface Summary Table 3. Disk Interface Summary IDE • All virtual machines must boot from an IDE device. • A maximum of four IDE devices are available for each virtual machine.
Figure 6. VHD I/O Path Passthrough The disk I/O request flows from the guest application through the storage stack of the guest OS and into the parent partition. Unlike VHDs that have a file system, volume, and disk partition in the parent partition, the passthrough disk is a raw device. Therefore, the I/O request is routed directly into the remainder of the parent partition's storage stack and onto the physical device.
Figure 7. Passthrough I/O Path Dell Supported Storage Arrays Storage arrays provide the capability to support Microsoft Failover Clusters and in turn provide support for highly available virtual machines and virtual machine migration. This section provides information on supported Dell PowerVault™, Dell EqualLogic™, and Dell|EMC™ arrays, an overview of configuration steps, and associated best practices. Table 4.
iSCSI Arrays In addition to supporting the features described for all storage arrays, iSCSI arrays also provide support for booting from an iSCSI SAN (BFi) where the Windows 2008 Server files, including the Hyper-V additions, reside on a disk on the iSCSI array. For more information on BFi, refer to the whitepaper, Dell PowerEdge™ Systems Instructions to Perform Boot from iSCSI for Dell Storage Arrays at support.dell.com/support/edocs/network/BFi.
Figure 8. Dell EqualLogic PS Series (Single Array) To provide VMs with access to storage residing on a Dell EqualLogic PS series array: 1 Confirm that your planned configuration is supported (see www.equallogic.com/resources/technicaldocumentsview.aspx). NOTE: The minimum required host software version is HIT 3.1.1. The recommended array firmware version is 4.0.1 or later. 2 Establish connectivity between the server and the array, and then provision LUNs to the server (see www.equallogic.
• For information on appropriately sizing the LUNs, see "Sizing Storage for Your VM" on page 30. • LUNs that store virtual machine data should reside on a fault tolerant RAID group. • Each virtual machine should have its own unique set of LUNs that contain the virtual machine files and virtual machine hard drives.
To provide VMs with access to storage residing on a Dell PowerVault MD3000i: 1 Confirm that your planned configuration is supported (see the MD3000i Support Matrix at support.dell.com/support/edocs/systems/md3000i). NOTE: The minimum versions required for support are array firmware version 06.70.17.60 and host software Resource CD version A04 (contains MPIO DSM v01.02.36.19).
NOTE: xxxx represents a four-digit string. Multiple entries may be present; however, only one entry will contain the Parameters\LinkDownTime path. e In the right pane of the Registry Editor window, verify that the key value is set to 0x00000090 (144). f Close the Registry Editor window and reboot the system. 3 Register the server in MDSM and provision LUNs to the server (see the Dell PowerVault Modular Disk Storage Manager User’s Guide at support.dell.com/support/edocs/systems/md3000i).
c In the right pane of the Registry Editor window, verify that the key value is set to 0x000000a0 (160). d Close the Registry Editor window and reboot the VM. For VMs running a Linux operating system with the 2.6 kernel, perform the following steps: a Create a new udev rule by creating a file with the name 96-dellsto.rules at /etc/udev/rules.d/.
Figure 10. Dell|EMC CLARiiON (iSCSI Array) To provide VMs with access to storage residing on a Dell|EMC CLARiiON array: 1 Confirm that your planned configuration is supported (see the EMC Support Matrix and Virtualization Server Support at elabnavigator.emc.com). NOTE: The following minimum versions are required for support: Array: • CX4 Series: FLARE 28 • CX3 Series: FLARE 26 • AX4-5i: FLARE 23 • AX150i: FLARE 20 Host software: • PowerPath 5.
NOTE: Follow the steps for Windows Server 2008 within the documentation. The configuration and software installation detailed in the guide should be carried out in the parent partition. Best practices during configuration: • For information on appropriately sizing the LUNs, see "Sizing Storage for Your VM" on page 30. • LUNs that store virtual machine data should reside on a fault tolerant RAID group.
Figure 11. Dell|EMC CLARiiON (Fibre Channel Array) To provide VMs with access to storage residing on a Dell|EMC CLARiiON array: 1 Confirm that your planned configuration is supported (see the EMC Support Matrix and Virtualization Server Support at elabnavigator.emc.com). NOTE: The following minimum versions are required for support: Array: • CX4 Series: FLARE 28 • CX3 Series: FLARE 26 • CX300/500/700: FLARE 26 • AX4-5f: FLARE 23 • AX150: FLARE 20 Host software: • PowerPath 5.
NOTE: Follow the steps for Windows Server 2008 within the documentation. The configuration and software installation detailed in the guide should be carried out in the parent partition. Best practices during configuration: • For information on appropriately sizing the LUNs, see "Sizing Storage for Your VM" on page 30. • LUNs that store virtual machine data should reside on a fault tolerant RAID group.
Figure 12. Dell PowerVault MD3000 To provide VMs with access to storage residing on a MD3000: 1 Confirm that your planned configuration is supported (see the MD3000 Support Matrix at support.dell.com/support/edocs/systems/md3000). NOTE: The minimum versions required for support are array firmware version 06.70.17.60 and host software Resource CD version A05 (contains MPIO DSM v01.02.36.19).
• LUNs that store virtual machine data should reside on a fault tolerant disk group. • Each virtual machine should have its own unique set of LUNs that contain the virtual machine files and virtual machine hard drives. 4 Provide virtual machines with the provisioned storage as either passthrough disks or format the disks and place VHDs on the formatted partition (see "Appendix B: Preparing Storage for Your VMs" on page 40).
Additional Dell Supported Storage Solutions Internal Storage Any Dell internal storage device that is supported by Windows Server 2008 x64 is also supported by Hyper-V. Refer to the device documentation to confirm Windows Server 2008 x64 support. Host-Based RAID With External Enclosures Any host-based RAID controller (with external enclosure) that is supported by Windows Server 2008 x64 is also supported by Hyper-V. Refer to the device documentation to confirm Windows Server 2008 x64 support details.
The information in this section is meant to help you understand the space that will be utilized for your virtual machines. The worksheet below can be utilized for each VM in your solution. Component Notes Guest OS Base Image Size:_______ The guest OS will reside on the boot IDE device of the VM. Guest OS Page File Size:_________ Recommended size is 1.5 times the amount of RAM allocated to the VM.
Sizing for VHDs Each LUN should be sized to support the target VHD. If the VM files will be stored on the LUN, then that must be taken into account as well. To avoid warning messages generated by the parent partition concerning disk running out of capacity, the LUN should have an addition 200MB allocated and this should be left as empty space on the volume. NOTE: For increased performance, fixed disk VHDs are recommended. It is also recommended that each VHD be placed on its own LUN (see Figure 14).
checkpoint is taken, a differencing disk is created for all VHDs assigned to the VM. The disk space required for the checkpoint files depends upon the frequency checkpoints are created, the rate of change of data, and the amount of memory assigned to the virtual machine.
Direct iSCSI Connectivity Within Guest OS To successfully create direct iSCSI connections within the guest OS, the guest OS must: • Support an iSCSI software initiator. • Be supported by the storage device. • Have the required storage device specific drivers and software installed. Setup and configuration of the iSCSI connection within the guest OS is the same as that for a physical server running the same OS. Refer to the storage device documentation for setup and configuration information.
Figure 17. iSCSI Connections From the Parent Partition and Guest OS Direct iSCSI Connection Storage I/O Path The disk I/O request flows from the guest application through the storage stack of the guest OS. The request is then placed into an iSCSI packet(s) and is transmitted through the networking stack of the guest OS, the networking stack of the parent partition, and to the iSCSI storage array.
Figure 18. iSCSI Direct From Guest OS I/O Path iSCSI Connection Summary Table 6.
iSCSI Initiator Running In Advantages (continued) Guest • Imported/exported VM does • Only supported on data not require modification of volumes storage array settings for iSCSI • Each Guest OS that connects direct LUNs reduces the number of host • In physical to virtual (P2V) connections available by the conversions, reconfiguration storage array* after conversion of the iSCSI • VSS host-based snapshots initiator or target is not (initiated in the parent required partition) do not capture the • Allows h
Appendix A: Planning for iSCSI-Based Storage Area Networks (SAN) Use the following best practices to enhance performance and high availability in the Hyper-V server, the networking environment, and iSCSI traffic. Physical Server Hosting Hyper-V • Use a minimum of two network adapters for high availability. If possible, the adapters selected should not reside on the same physical adapter. For example, one adapter may be from the LAN on motherboard (LOM) and the other may be from an add-in network card.
• Disable Unicast Storm Control on each switch that processes iSCSI traffic. • Enable Jumbo Frames on each switch and NIC that processes iSCSI traffic. • Use the proper iSCSI optimization settings for your iSCSI storage solution. See the documentation for your iSCSI storage solution. • Disable Spanning Tree Protocol (STP). STP may introduce a large delay before the switch port enters the forwarding mode, introducing undesirable network latency.
Appendix B: Preparing Storage for Your VMs Use the following procedures to prepare a raw disk for a VM after a LUNs has been provisioned to the parent partition.
Preparing the Disk for Storing VHDs or VM Files Both VHDs and VM files (configuration, saved state data, etc) must reside on a formatted partition. Perform the following steps after provisioning LUNs to the parent partition: 1 Using Disk Management or diskpart, place an NTFS partition on the provisioned disks and assign a drive letter to the partition.
Appendix C: Glossary B F I — Booting a system from a LUN residing on a iSCSI storage array G U E S T OS — The operating system that is running within a virtual machine. H Y P E R - V M A N A G E R — The Microsoft Management Console (MMC) that manages the Hyper-V Virtualization Role on Windows Server 2008. H Y P E R V I S O R — A layer of software that sits just above the hardware and below the parent partition and VMs. Its primary job is to provide isolated execution environments called partitions.
Appendix D: References • Dell Solutions for Windows Server 2008 Hyper-V at www.dell.com/hyper-v – Dell Virtualization Solutions Advisor Tool – Dell Solutions Overview Guide for Microsoft Hyper-V – Dell Networking Solutions Guide for Microsoft Hyper-V – Dell Storage Solutions Guide for Microsoft Hyper-V – Dell Virtualization Reference Architecture for Microsoft Hyper-V • Hyper-V RTM Update - Microsoft KB950050 from http://support.microsoft.
Storage Solutions Guide
