• Setting Up a Windows or Mac OS Host to Use LUN storage over iSCSI

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    Setting Up a Windows or Mac OS Host to Use LUN storage over iSCSI

    Requirements for setting up a host

    These system and network requirements must be met before setting up a host to use Unity storage.

    Before you can set up a host to use Unity storage, the following storage system and network requirements must be met.

    Overview

    This document describes how to configure the following hosts to access Fibre Channel (FC) or iSCSI storage provisioned on a system running the latest operating environment:

    • Windows hosts
    • AIX hosts
    • Citrix XenServer hosts
    • HP-UX hosts
    • Linux hosts
    • Solaris hosts

    This document is intended for those who are responsible for setting up host to access storage.

    Readers of this document should be familiar with FC or iSCSI LUNs and with the operating system running on the hosts that will access the LUNs.

    The Unisphere online help provides specific information about storage, features, and functionality. The online help and a complete set of documentation are available on the EMC Online Support website.

    System requirements

    Before configuring hosts to access the storage system, ensure that these requirements are met.

    Complete the following tasks before connecting hosts to the storage system:

    • Install and configure the system using the Initial Configuration wizard.
    • Use Unisphere or the CLI to configure NAS servers or interfaces, or iSCSI or Fibre Channel (FC) LUNs, on the storage system.

    Network requirements

    For a host to connect to LUNs on an iSCSI interface, the host must be in the same network environment with the iSCSI interface. To achieve best performance, the host should be on a local subnet with each iSCSI interface that provides storage for it. In a multi-path environment, each physical interface must have two IP addresses assigned; one on each SP. The interfaces should be on separate subnets.

    To achieve maximum throughput, connect the iSCSI interface and the hosts for which it provides storage to their own private network. That is, a network just for them. When choosing the network, consider network performance.

    Path management network requirements

    Path management software is not supported for a Windows 7 or Mac OS host connected to a Unity system.

    When implementing a highly-available network between a host and your system, keep in mind that:

    • A LUN is visible to both SPs
    • You can configure up to 8 IPs per physical interface. If more than one interface is configured on a physical interface, each interface must be configured on a separate VLAN.
    • Network switches may be on separate subnets.
    Directly attaching a host to a Unity system is supported if the host connects to both SPs and has the required multipath software.

    The following figure shows a highly-available iSCSI network configuration for hosts accessing a storage resource (iSCSI LUNs). Switch A and Switch B are on separate subnets. Host A and Host B can each access the storage resource through separate NICs. If the storage resource is owned by SP A, the hosts can access the storage resource through the paths to the interfaces on SP A. Should SP A fail, the system transfers ownership of the resource to SP B and the hosts can access the storage resource through the paths to the interfaces on SP B.

    Figure 1. Highly-available iSCSI network sample
    Highly-available iSCSI network sample

    VSS HW Provider overview

    The VSS HW Provider runs as a Windows service and provides the interface between the Microsoft Volume Shadow Copy Service (VSS) and your storage system. The VSS HW Provider enables VSS requestor applications, such as VSS-enabled backup applications, to make snapshots of iSCSI and FC LUNs.

    Microsoft VSS

    VSS provides the backup framework for Windows Server 2003 R2, Windows Server 2008, and Windows Server 2012 and enables the creation of snapshots (called shadow copies for Microsoft VSS) — point-in-time copies of data. VSS is integrated with front-end applications so they can create and access shadow copies.

    The VSS architecture includes VSS providers. A VSS provider creates and maintains shadow copies and acts as the interface to point-in-time imaging capabilities either on a storage platform (hardware-based provider) or in a host operating system (software-based provider). The Unity VSS HW Provider is a hardware-based provider that works directly with iSCSI and FC LUNs on the Unity iSCSI and FC interfaces and with the VSS service on Windows Server 2003 R2, Windows Server 2008, or Windows Server 2012 hosts to provide consistent shadow copy creation and addressing.

    Because the Unity VSS HW Provider is a hardware-based provider, it reduces the load on the CPU and memory of the host. It is also more efficient in an environment where shadow copies of multiple volumes must be taken simultaneously.

    Refer to the Microsoft documentation for more information about VSS.

    Windows host — Using multi-path management software over iSCSI

    Multi-path management software manages the connections (paths) between the host and the storage system to provide access to the storage if one of the paths fails. The following types of multi-path management software are available for a Windows 2003, Windows Server 2008, or Window Server 2012 connected host :

    • EMC PowerPath software on a Windows 2003, Windows Server 2008, or Windows Server 2012 host. Refer to the Unity Support Matrix on the support website for compatibility and interoperability information.
      PowerPath is not supported for Windows 7.
    • Native MPIO on Windows 2003, Windows Server 2008, or Windows Server 2012 without Multiple Connections per Session (MCS).
      The MultiPath IO feature must first be enabled before it can be used.

      MCS is not supported by Unity.

    For information on data availability in your Unity system and your connectivity infrastructure, refer to EMC Unity High Availability, A Detailed Review white paper.

    Setting up your system for multi-path management software

    For your system to operate with hosts running multi-path management software, two iSCSI IPs are required. These IPs should be on separate physical interfaces on separate SPs.

    Verify the configuration in Unisphere. For details on how to configure iSCSI interfaces, refer to topics about iSCSI interfaces in the Unisphere online help.

    For highest availability, use two network interfaces on the iSCSI interface. The network interfaces should be on separate subnets. You can view the network interfaces for an iSCSI interface within Unisphere.

    Installing PowerPath

    Procedure
    1. On the host or virtual machine, download the latest PowerPath version from the PowerPath software downloads section on the EMC Online Support website.
    2. Install PowerPath as described in the appropriate PowerPath installation and administration guide for the host’s or virtual machine’s operating system.
      This guide is available on EMC Online Support. If the host or virtual machine is running the most recent version and a patch exists for this version, install it, as described in the readme file that accompanies the patch.
    3. When the installation is complete, reboot the host or virtual machine.
    4. When the host or virtual machine is back up, verify that the PowerPath service has started.

    Configuring iSCSI LUNs for the host

    Use Unisphere or the CLI to:
    Procedure
    1. Create storage over iSCSI for the host.
    2. Add the host to the storage system in Unisphere or by using the Unity CLI and creating a host. If your host is not already logged in, manually create an iSCSI initiator by providing the host IQN.
    3. Provide host access to the storage over iSCSI. Host access options are: No Access, LUN, Snapshot, LUN and Snapshot.
      On a Mac OS host, the Xtend SAN iSCSI initiator will not log into the iSCSI storage if no vdisk0 is configured on the target (iSCSI interface). We recommend that you to create a unique iSCSI interface, create an iSCSI resource on this iSCSI interface, and provide access to the Mac OS host. The first LUN that you create on this iSCSI resource is vdisk0.

      For information on performing the above Unisphere tasks, refer to the Unisphere online help.

    Windows host — Setting up for iSCSI LUNs

    Install the Unity VSS HW Provider

    Installing the Unity VSS HW Provider (for Windows Server 2003, Windows Server 2008, and Windows Server 2012) is optional. However, if you plan to take application consistent snapshots using backup software, you must install the Unity VSS HW Provider.

    It is recommended that you install the VSS HW Provider on the host that will use the iSCSI or FC LUNs with backup applications.

    To install the Unity VSS HW Provider:

    Procedure
    1. Log in to the host using an account with administrator privileges.
    2. Download the software package that you want to install as follows:
      1. Locate the Unity VSS tool on online support.
        You may need to filter by Support Tools.
      2. Choose the correct version for your Windows platform, and select the option to save the software to the host.
    3. In the directory where you saved the software, double-click the Unity VSS provider executable file to start the installation wizard.
    4. Follow the instructions in the wizard to complete the installation of the Unity VSS provider.

    Starting and stopping the Unity VSS HW Provider

    The Unity VSS HW Provider runs as a Windows service and is enabled by default. You can stop and start this service from the Windows Services administrative tool.

    Install the Microsoft iSCSI Initiator and iSCSI initiator service on the Windows host (Windows Server 2003 and Windows Server 2008 SP2)

    To connect to the iSCSI targets (iSCSI interfaces), the host uses an iSCSI initiator, which requires the Microsoft iSCSI Software Initiator and the iSCSI initiator service software. This software is not included with the Windows Server 2003 operating system software, so you must install it on the host if the host is running Windows Server 2003. When you install the software on the host, the iSCSI initiator software starts.

    To install the Microsoft iSCSI Initiator and iSCSI service:

    Procedure
    1. Download the latest iSCSI initiator software and related documentation from the Microsoft website to the host.
    2. After you download the appropriate software, double-click the executable to open the installation wizard, click Next in the Welcome page, and follow the steps in the installation wizard.
    3. If this is an upgrade of existing iSCSI initiator software, you must restart the host.
    4. For shared storage, make the LanManServer service dependent on the iSCSI initiator service by starting the LanManServer before the iSCSI initiator service with the following command:
                                    sc config LanManServer depend= MSiSCSI
                                  
      If you use LanManServer on a Windows Server 2003 host to set up shares on an iSCSI resource, these shares are available only after you reboot the host because the LanManServer service starts before the iSCSI initiator service.

    Start the iSCSI initiator service (Windows Server 2008 R2 and Windows Server 2012)

    To connect to the targets (iSCSI interfaces), the host uses an iSCSI initiator, which requires the Microsoft iSCSI Software Initiator software and the iSCSI initiator service. This software and service are part of the Windows Server 2008 software; however, the driver for it is not installed until you start the service. You must start the iSCSI initiator service using the administrative tools.

    If the host is behind a Windows firewall, Microsoft asks if you want to communicate through the firewall. Before proceeding, we suggest that you consult with your network support administrator.

    For a multi-path configuration, install the MPIO feature (Windows 2003 and Windows Server 2008 SP2)

    This task is mandatory. Powerpath is an alternative to Native MS MPIO.

    If the Windows host will use a multi-path configuration to connect to the LUNs, you should install the MPIO feature. To install MPIO on Windows Server 2008:

    Procedure
    1. Open Server Manager.
    2. In the Server Manager tree, click Features.
    3. In the Features pane, under Features Summary, click Add Features.
    4. In the Add Features Wizard, select Multipath I/O, and click Next.
    5. In the Confirm Installation Selections dialog box, click Install.
    6. When the installation is complete, in the Installation Results dialog box, click Close.
    7. When prompted to restart the computer, click Yes.
      After restarting, the host finalizes the MPIO installation.
    8. Click Close.

    Set registry values

    Incorrectly modifying the Registry can cause serious system-wide problems that can require you to reinstall the system. Use the Windows Registry Editor at your own risk.
    Procedure
    1. On the host, run the Windows Registry Editor (regedit.exe).
    2. Go to HKEY_LOCAL_MACHINE\SYSTEM\.
    3. Right-click CurrentControlSet, and search for the MaxRequestHoldTime key and modify its value from 60 to 600 (decimal) or from 3c to 258 (hexadecimal).
      Verify that the path to the parameter that you found in the CurrentControlSet. If it is not, search for the parameter again. If you make changes to ControlSets other than the top level current set, those changes will not affect the system.
    4. If the host is running PowerPath:
      1. Search for the register keys list in Table 1.
        Verify that the path to the parameter that you found in the CurrentControlSet. If it is not, search for the parameter again. If you make changes to ControlSets other than the top level current set, those changes will not affect the system.
      2. Record the value of each of these registry keys, so you have them in case you need to uninstall PowerPath.
      3. Update each of these registry keys. See Table 1.
        Table 1. Registry keys to update (iSCSI only)
        Registry keys
        Instructions
        LinkDownTime
        Set to 600.
        AsyncLogoutPauseTimeout (new value)
        Add this REG_DWORD key in the same key as LinkDownTime. Set it to 600.
        DelayBetweenReconnect

        PortalRetryCount

        Find the DelayBetweenReconnect value. Set the PortalRetryCount value so that PortalRetryCount*DelayBetweenReconnect=600
        SrbTimeoutDelta (for PowerPath only)
        Set to 100 for PowerPath only.
    5. Quit the Registry Editor.

    Windows host — Configuring to connect to an iSCSI interface

    Before an initiator can establish a session with a target, the initiator must discover where the targets are located and the names of the targets available to it. To obtain this information the initiator uses the iSCSI discovery process. The iSCSI interfaces support discovery with or without an iSNS server. Without iSNS discovery, you must add the target information to the Microsoft iSCSI Initiator. With iSNS discovery, the initiator queries the iSNS server where all iSCSI initiators and targets register themselves, and the server responds with a list of available targets. When the target information is available to the Microsoft iSCSI Initiator, you can connect the host initiator to the target so the host can access the iSCSI LUNs.

    Unless you are using iSCSI targets in a clustered environment, avoid giving more than one initiator access to the same LUN. Conflicts can occur if more than one initiator tries to write to the LUN. If the LUN is formatted with the NTFS file system in Windows, simultaneous writes can corrupt the NTFS file system on the LUN.

    Each iSCSI interface is a target. If a storage system has two iSCSI interfaces, it has two targets. Each target has one session.

    To connect to an iSCSI target, you must add the target IP address in Microsoft iSCSI Initiator. If you have multiple targets (iSCSI interfaces), you can use the Microsoft iSCSI initiator to discover the targets through an individual IP address.

    To configure the Windows host initiators:

    Go to the section below for the host’s configuration:

    For Windows Server 2003 or Windows Server 2008 SP2 or earlier: For Windows Server 2008 R2 or Windows Server 2012:

    Setting Up MPIO for a Windows Cluster Using a Storage System gives an end-to-end example of setting up a two-node Windows Server 2008 R2 Exchange cluster in an MPIO multi-path configuration.

    For Windows 7:

    Configuring a Windows 7 initiator to connect to a storage system iSCSI interface

    Configuring a Windows Server 2003 or Windows Server 2008 SP2 or earlier initiator to connect to an iSCSI interface — multi-path configuration

    Before you configure a Windows Server 2003 or Windows Server 2008 SP2 or earlier initiator to connect to an iSCSI interface in a multi-path configuration:

    • You must have configured the iSCSI interface with two IP interfaces on two separate physical ports. Each IP interface should be on a separate IP subnet.
    • The Windows host must have two network interfaces. One interface must be on the IP subnet with one of the storage system iSCSI interfaces, and the other interface must be on the IP subnet with the other storage system iSCSI interface.

    To configure a Windows Server 2003 or Windows Server 2008 SP2 or earlier initiator to connect to an iSCSI interface in a multi-path configuration, perform these tasks:

    MCS is not supported.

    Setup optional mutual CHAP — Windows Server 2003 or Windows Server 2008 SP2 or earlier in multi-path configuration

    To configure optional mutual Challenge Handshake Authentication Protocol (CHAP) you need the mutual CHAP secret specified for the storage system iSCSI interface.

    For the storage system iSCSI interface to which you want the host iSCSI initiator to access:

    Procedure
    1. On the host, start the Microsoft iSCSI Initiator.
    2. If mutual CHAP authentication is configured on the storage system iSCSI interface, then in the Microsoft iSCSI Initiator:
      1. Click the General tab and select Secret.
      2. In the CHAP Secret Setup dialog box, enter the mutual CHAP secret for the storage system iSCSI interface.
        If the storage system has multiple iSCSI interfaces, this secret is the same for all. You can find this secret in the CHAP section on the Access settings page in Unisphere ( Settings > Access > CHAP).
      3. Click OK.

    Discover the storage system iSCSI interface in an environment — Windows Server 2003 or Windows Server 2008 SP2 or earlier in a multi-path configuration

    If the host initiator is configured for optional initiator Challenge Handshake Authentication Protocol (CHAP) on the storage system iSCSI interface, you need the secret (password) specified for the initiator on the storage system.
    Procedure
    1. On the host, start the Microsoft iSCSI Initiator.
    2. Click the Discovery tab.
    3. Under Target Portals, click Add.
      The Add Target Portal dialog box opens.
    4. In the Add Target Portal dialog box:
      1. Enter the IP address of the storage system iSCSI interface on the first subnet with the host interface. You can find this address with Unisphere by selecting Storage > Block > iSCSI Interfaces.
      2. Click Advanced.
        The Advanced Settings dialog box opens.
    5. In the Advanced Settings dialog box, set the following:
      • Local adapter to Microsoft iSCSI Initiator.
      • Source IP to the IP address of the host interface on the first subnet with the storage system iSCSI interface.
    6. If the host initiator is configured for optional initiator CHAP on the storage system iSCSI interface:
      1. Select CHAP logon information.
      2. Leave User name as the default value, which is the initiator’s IQN.
      3. Set Target secret to the same secret that is configured for the host initiator on the storage system iSCSI interface. The storage system iSCSI interfaces support CHAP secrets of 12 to 16 characters only.
      4. If the iSCSI interface is configured for mutual CHAP, select Perform Mutual Authentication.
    7. Click OK to close the Advanced Settings dialog box.
    8. Click OK to close the Add Target Portal dialog box.
    9. In the Discovery tab, verify that the address of the first iSCSI interface appears in the Target Portals list.
    10. Click the Targets tab. The IQNs representing the ports configured on the storage system appear in the Targets list with an Inactive status.
    11. In the Targets tab, select a storage system iSCSI interface target name, and click Log On. The Log On to Target dialog box opens.
    12. In the Log On to Target dialog box:
      1. Select Automatically restore this connection when the system reboots.
      2. Select Enable multi-path.
      3. Click Advanced. The Advanced Settings dialog box opens.
    13. In the Advanced Settings dialog box, set the following:
      • Local adapter to Microsoft iSCSI Initiator.
      • Source IP to the address of the host interface on the first subnet with the storage system iSCSI interface.
      • Target Portal to the address of the storage system iSCSI interface on the first subnet with the host interface.

        To find the IP address associated with this IQN, note the IQN name, and then go to Storage > Block > iSCSI Interfaces in Unisphere.

    14. If the host initiator is configured for optional initiator CHAP on the storage system iSCSI interface:
      1. Select CHAP logon information.
      2. Leave User name as the default value, which is the initiator’s IQN.
      3. Set Target secret to the same secret that is configured for the host initiator on the storage system iSCSI interface. The iSCSI interfaces support CHAP secrets of 12 to 16 characters only.
      4. If the storage system iSCSI interface is configured for mutual CHAP, select Perform Mutual Authentication.
    15. Click OK to close the Advanced Settings dialog box.
    16. Click OK to close the Log On to Target dialog box.
    17. Repeat steps 11 through 16 for all other targets listed in the Targets tab. Ensure that the relevant IP addresses are selected accurately. Once logged on, each listed target must appear with the Connected status.

    Identify and set active paths to the storage system

    This section does not apply to multi-path configuration with PowerPath.

    The Microsoft iSCSI Initiator may not accurately identify the active paths to the storage system. Complete the following steps to identify and set the active paths:

    To achieve effective load-balancing, ensure that only paths to the SP that owns the LUN are set as Active. Setting paths to the standby SPs as Active can cause issues in your implementation.
    Procedure
    1. In the Targets tab, select a storage system iSCSI interface target, and click Details.
      The Target Properties dialog box opens.
    2. On the Devices tab, click Advanced. The Device Details dialog box opens.
    3. Click the MPIO tab. This tab lists all valid paths, with a single path set as Active. This path goes to the SP owner of the storage resource.
    4. Ensure that Load Balance Policy is set to Round Robin With Subset.
    5. Click the interface with the path set as Active, and click Details.
    6. In the MPIO Path Details dialog box, note the value in the Target Portal column. This is the IP address associated with the iSCSI interface created on the relevant port of the SP.
    7. Click OK to close the MPIO Path Details dialog box.
    8. For each interface with the path set as Standby, click Details to launch the associated MPIO Path Details dialog box.
    9. Review the value in the Target Portal column, and identify the interface that has path to the same SP as the interface with the path set as Active.
      In Unisphere, go to Settings > iSCSI Settings to review the list of interfaces/IP addresses with path to the same SP.
    10. For the interface with the path to the same SP, on the MPIO tab, click Edit.
    11. In the Edit Settings dialog box, set Path Type to Active.
    12. Click OK to close the Edit Settings dialog box.
    13. On the MPIO tab, verify that the interface appears with the path set as Active.
    14. Click OK to close the Device Details dialog box.
    15. Click OK to close the Target Properties dialog box.
    16. Click OK to exit the Microsoft iSCSI Initiator.

    Configuring a Windows Server 2008 R2 or Windows Server 2012 initiator to connect to a storage system iSCSI interface — multi-path configuration

    Before you configure a Windows Server 2008 R2 initiator to connect to a storage system iSCSI interface in a multi-path configuration:

    • You must have configured the storage system iSCSI interface with two IP interfaces on two separate physical ports. Each IP interface should be on a separate IP subnet.
    • The Windows host must have two network interfaces. One interface must be on the IP subnet with one of the storage system iSCSI interfaces, and the other interface must be on the IP subnet with the other storage system iSCSI interface.

    To configure a Windows Server 2008 R2 or later initiator to connect to a storage system iSCSI interface in a multi-path configuration, perform these tasks:

    MCS is not supported.

    Setup optional mutual CHAP — Windows Server 2008 R2 in multi-path configuration

    To configure optional mutual Challenge Handshake Authentication Protocol (CHAP) you need the mutual CHAP secret specified for the storage system iSCSI interface.

    For the storage system iSCSI interface to which you want the host iSCSI initiator to access:

    Procedure
    1. On the host, start the Microsoft iSCSI Initiator.
    2. If mutual CHAP authentication is configured on the storage system iSCSI interface, then in the Microsoft iSCSI Initiator:
      1. Click the Configuration tab.
      2. On the Configuration tab, click CHAP.
        The iSCSI Initiator Mutual Chap Secret dialog box opens.
      3. In the iSCSI Initiator Mutual Chap Secret dialog box, enter the mutual CHAP secret for the storage system iSCSI interface.
        If the storage system has multiple iSCSI interfaces, this secret is the same for all. You can find this secret in the CHAP section on the Access settings page in Unisphere ( Settings > Access > CHAP Interfaces).
      4. Click OK.

    Configure MPIO to recognize iSCSI devices

    This section does not apply to multi-path configuration with PowerPath.
    Procedure
    1. Launch the MPIO application.
    2. On the MPIO Properties dialog box, click the Discover Multi-Paths tab.
    3. Under SPC-3 compliant, select Add support for iSCSI devices.
    4. Click Add. A Reboot Required dialog box opens.
    5. In the Reboot Required dialog box, click Yes.
    6. Once the server reboots, launch the MPIO application, and verify that the MPIO is configured to claim all iSCSI devices.

    Discover the storage system iSCSI interface in an environment — Windows Server 2008 R2 in multi-path configuration

    If the host initiator is configured for optional initiator Challenge Handshake Authentication Protocol (CHAP) on the storage system iSCSI interface, you need the secret (password) specified for the initiator on the system.
    Procedure
    1. On the host, start the Microsoft iSCSI Initiator.
    2. Click the Discovery tab.
    3. Under Target Portals, click Discover Portal.
      The Discover Target Portal dialog box opens.
    4. In the Discover Target Portal dialog box:
      1. Enter the IP address of the storage system iSCSI interface on the first subnet with the host interface.
        You can find this address with Unisphere by selecting Storage > Block > iSCSI Interfaces.
      2. Click Advanced.
        The Advanced Settings dialog box opens.
    5. In the Advanced Settings dialog box, set the following:
      • Local adapter to Microsoft iSCSI Initiator.
      • Initiator IP to the IP address of the host interface on the first subnet with the storage system iSCSI interface.
    6. If the host initiator is configured for optional initiator CHAP on the storage system iSCSI interface:
      1. Select Enable CHAP logon.
      2. Leave Name as the default value, which is the initiator’s IQN.
      3. Set Target secret to the same secret that is configured for the host initiator on the storage system iSCSI interface.
        The iSCSI interfaces support CHAP secrets of 12 to 16 characters only.
      4. If the storage system iSCSI interface is configured for mutual CHAP, select Perform Mutual Authentication.
    7. Click OK to close the Advanced Settings dialog box.
    8. Click the Targets tab.
    9. In the Targets tab under Discovered Targets, select the storage system iSCSI target and click Connect.
      The Connect to Target dialog box opens.
    10. In the Connect to Target dialog box:
      1. Verify that Add this connection to the list of Favorite Targets is selected.
      2. Select Enable Multi-path.
      3. Click Advanced.
        The Advanced Settings dialog box opens.
    11. In the Advanced Settings dialog box, set the following:
      • Local adapter to Microsoft iSCSI Initiator.
      • Initiator IP to the address of the host interface on the first subnet with the storage system iSCSI interface.
      • Target portalIP to the address of the storage system iSCSI interface on the first subnet with the host interface.

      You can find this address with Unisphere by selecting Storage > Block > iSCSI Interfaces.

    12. Click OK to close the Advanced Settings dialog box.
    13. Click OK to close the Connect to Target dialog box.
    14. Repeat steps 8 through 13 for all other targets listed in the Targets tab. Ensure that the relevant IP addresses are selected accurately. Once connected, each listed target must appear with the Connected status.

    Review the paths to the SP

    This section does not apply to multi-path configuration with PowerPath.
    Procedure
    1. In the Targets tab, select a storage system iSCSI interface target, and click Devices.
    2. On the Devices dialog box, under Configure Multipath IO (MPIO), click MPIO. The Device Details dialog box opens.
      This tab lists all valid paths, with a single path set as Active. This path goes to the SP owner of the storage resource.
    3. In the MPIO tab, ensure that Load Balance Policy is set to Round Robin With Subset.
    4. Review the list of paths to each device, and verify that they are set to Active.
      Although all paths may appear as Active, it does not mean that the I/O operations will be active on all connections. The I/O will be directed only to the paths on the SP that owns the device or storage resource.
    5. Click OK to close the Properties dialog box.
    6. Click OK to exit the Microsoft iSCSI Initiator.

    Verify the paths MPIO will use for load balancing

    This section does not apply to multi-path configuration with PowerPath.
    Procedure
    1. Launch the MPIO application.
    2. On the MPIO Properties dialog box, click the Configuration Snapshot tab.
    3. Under Snapshot, specify a path and file name for the output.
    4. Select Open File upon capture, and then click Capture.
      The output will appear in a text editor. It lists available paths to each device or storage resource. Note the following:
      • Paths with Active/Optimized state are used to balance I/O to a storage resource.
      • Paths with Active/Unoptimized state are used for failovers only.

    Configuring a Windows 7 initiator to connect to a storage system iSCSI interface

    If the host initiator is configured for optional initiator Challenge Handshake Authentication Protocol (CHAP) on the storage system iSCSI interface, you need the secret (password) specified for the initiator on the storage system.

    To configure a Windows 7 to connect to a storage system:

    Procedure
    1. On the host, start the Microsoft iSCSI Initiator.
      On way to start the iSCSI Initiator is by going to the Control Panel and selecting All Control Panel Items > Administrative Tools > iSCSI Initiator.
    2. If prompted to start the iSCSI service, click Yes.
    3. In the Targets tab, enter the IP address of the storage system iSCSI interface and click Quick Connect.
    4. In the Quick Connect window under Discovered targets, select the storage system iSCSI interface and click Connect.
      The storage system iSCSI LUNs on the target (storage system iSCSI interface) for the host are added to Windows 7.
    5. Click Done.
      The connection to the storage system iSCSI interface appears on the Targets tab as Connected.
    6. Click the Volumes and Devices tab and click Auto Configure.
      The LUNs are connected to the host.

    Windows host — Setting up to use iSCSI or FC LUNs

    Register the LUNs as MPIO devices (Windows Server 2008 R2 and Windows Server 2012)

    If you are using Multipath I/O (MPIO) with Windows Server 2008, you must register LUNs as MPIO devices and set up MPIO to discover iSCSI or FC devices:
    Procedure
    1. On the host, start the MPIO Administrative Tool:
      Either Start > Administrative Tools and select MPIO or Start > Run and enter mpiocpl.exe.
    2. Open the MPIO control panel, and click the Discover Multi-Paths tab.
    3. Select the Add support for iSCSI devices check box, and click Add.
    4. When prompted to restart the computer, click Yes.
      When the computer restarts, the MPIO Devices tab lists the additional hardware ID “MSFT2005iSCSIBusType_0x9.” When this hardware ID is listed, all iSCSI bus attached devices will be claimed by the Microsoft DSM.
    5. Restart the host when prompted.

    Set the offset for the LUN to 64 KB

    This task is only required for systems running Hyper-V on Windows Server 2003, or systems that were upgraded from Windows Server 2003 to Windows Server 2008 or later.

    After the initiator logs in to a target, each of the target’s LUNs that the initiator can access appears as an unknown disk in the Windows Disk Management tool.

    To set the offset for the LUN on the host:

    Procedure
    1. Select Run > diskpart.
    2. Select the disk:
                                    select disk n
                                  

      where n is the disk number.

      If you do not know the disk number, enter:

                                    list disk
                                  
    3. On the selected disk, create a primary partition with an offset of 64 KB:
                                    create part pri align=64
                                  

    Configure a volume on the LUN

    The following configuration process initializes the LUN, creates a partition, formats a volume on the partition, and mounts the partition on a drive letter:
    Procedure
    1. On the host, in the Microsoft Disk Management tool, select the LUN.
    2. If the system asks you to initialize the disk, click Yes, but do not choose to make the disk a dynamic disk because the iSCSI interfaces do not support dynamic disks.
      For a given LUN, its drive letter, disk number, and LUN number are independent.
    3. Use a quick format operation (Windows Server 2003 or Windows Server 2008) or the New Simple Volume wizard (Windows 7) to create a volume on the disk with the following properties:
      • NTFS file system
      • 64K location unit size
      Do not format more than one LUN at a time. Otherwise, some of the volumes can become write-protected and cannot be formatted.

      You can change the volume label. Because the disk number of a LUN can change after system restart or after logging in to and out of a target, be sure to change the default volume label (“New Volume”) to a descriptive label.

    4. Assign an available drive letter to the disk.
    5. Close the Disk Management tool.

    Mac OS host — Setting up for iSCSI LUNs

    Installing and configuring the ATTO Xtend SAN iSCSI Initiator on a Mac OS host

    To connect a host iSCSI initiator on a Mac OS host to iSCSI storage, you must install the ATTO Xtend SAN iSCSI Initiator and configure the initiator for the target.
    Procedure
    1. On the storage system, from the iSCSI Interfaces page in Unisphere (Storage > Block > iSCSI Interfaces), determine the IP address of the storage system iSCSI interface (target) to which you want the host initiator to connect. This iSCSI interface is the one with the iSCSI storage resources for the host.
    2. On the Mac OS host, insert the Xtend SAN CD into a CD drive, and following the steps in the installation wizard.
      An iSCSI Xtend SAN icon appears at the location where you chose to install the initiator.
    3. Double-click the iSCSI Xtend SAN icon.
    4. Click the Discover Targets tab.
    5. In the Discover Targets dialog box:
      1. Enter the IP address of the target, which is the IP address of the iSCSI interface with the iSCSI LUNs for the Mac OS.
      2. To use optional CHAP:
        • Enter the target user name.
        • Enter the target secret.
        • For optional CHAP mutual authentication, select the Mutual Authentication checkbox.
      3. Click Finish.
        The Setup dialog box appears, displaying the iqn of the discovered storage system target.
    6. In the Setup dialog box:
      1. Select Visible and Auto Login.
      2. Click Save.
    7. Click the Status tab.
    8. In the Status dialog box, click Login.
      When the login operation is complete, the red icon before the iqn name in the left panel turns green.
    9. Click LUNs to verify the connections.
      If the initiator is connected to the iSCSI interface, the iSCSI LUN for the host appears in the LUNs list.

    Set up a Mac OS host to use LUNs

    Before the Mac OS host can use a LUN, you must use the Mac OS Disk Utility to:

    1. Format the LUN
    2. Partition the LUN

    Format the LUN

    Procedure
    1. On the host, go to Finder > Application > Utilities.
    2. Double-click Disk Utility.
    3. In the left panel, select the LUN.
    4. Click the Erase tab.
    5. For Volume Format, select the format that you want, and confirm your format choice.
    6. Click Erase and verify the erase procedure, and click Erase again to start the erase process.
      When the erase process is finished, the LUN is ready for you to partition it.

    Partition the LUN

    Procedure
    1. On the host, go to Finder > Application > Utilities.
    2. Double click Disk Utility.
    3. In the left panel, select the LUN.
    4. Click the Partition tab.
    5. Under Volume Scheme, select the number of partitions for the LUN.
      The utility displays equal-sized partitions to fill the available space on the LUN.
    6. For each partition:
      1. Select the partition.
      2. In Name, enter a name for the partition.
      3. Under Format, select the format for the partition.
        The default format - Mac OS Extended (Journaled) - is a good choice for most uses.
      4. In Size, enter the size for the partition.
    7. When you have specified, the name, size, and format for each partition, click Apply.
      The Disk Utility uses the partition information to create volumes that the host can access and use. When the partitioning process is complete, the new volumes are mounted on the desktop and ready to use.

      You are now ready to either migrate data to the LUN or have the host start using the LUN. To migrate data to the LUN, go to Migrating FC or iSCSI Data to the Storage System.

    iSCSI troubleshooting

    iSCSI session troubleshooting

    Procedure
    1. Use ping with the IP address to verify connectivity from the host to the target’s IP address.
      Using the IP address avoids name resolution issues.
      You can find the IP address for the target by selecting Storage > Block > iSCSI Interfaces in Unisphere.

      Some switches intentionally drop ping packets or lower their priority during times of high workload. If the ping testing fails when network traffic is heavy, verify the switch settings to ensure the ping testing is valid.

    2. On the host, verify that the iSCSI initiator service is started.
      The iSCSI service on the iSCSI interface starts when the system is powered up.
    3. In the Microsoft iSCSI Initiator, verify the following for the target portal:
      • IP address(es) or DNS name of the storage system iSCSI interface with the host’s LUNs.
        For a host running PowerPath or Windows native failover, the target portal has two IP addresses.
      • Port is 3260, which is the default communications port for iSCSI traffic.
    4. Verify that the iSCSI qualified names (IQN) for the initiators and the iSCSI interface name for the target are legal, globally unique, iSCSI names.
      An IQN must be a globally unique identifier of as many as 223 ASCII characters.

      For a Windows host initiator — You can find this IQN on the General or Configuration tab of the Microsoft iSCSI initiator (depending on the version).

    5. If you are using optional CHAP authentication, ensure that the following two secrets are identical by resetting them to the same value:
      • The secret for the host initiator in the Microsoft iSCSI Software Initiator or the Linux open-iscsi driver.
      • The secret configured for the host initiator on the iSCSI interface.
    6. If you are using optional mutual CHAP authentication, ensure that the following two secrets are identical by resetting them to the same value:
      • The secret for the host initiator in the Microsoft iSCSI Software Initiator or the Linux open-iscsi driver.
      • The secret for the iSCSI interface on the iSCSI interface.

    Known Microsoft iSCSI Initiator problems

    The following table describes known problems that with the Microsoft iSCSI Initiator and describes workarounds.

    Table 2. Microsoft iSCSI Initiator problems
    Problem
    Symptom
    Workaround
    Initiator cannot refresh its targets list.
    If you use iSNS and an initiator is disconnected from the network, the initiator may not refresh its target list. When attempting to refresh the target list, the initiator logs the iSNS error auth unknown (0x6) to the Windows Event Log.
    1. Select Windows Administrative Tools > Services.
    2. Stop and restart the Microsoft iSCSI Initiator.
    Login problems occur when you use iSNS for target discovery.
    When you configure the initiator with iSNS target discovery, it can intermittently fail to log in to a target with the following error message: The target name is not found or is marked as hidden from login.
    The Microsoft iSCSI Initiator eventually recovers from this situation. To speed up the process, refresh the target list a few times until the target in question is discovered.
    Initiator messages fill up the Windows Event Log.
    If the initiator has an active session with an iSCSI interface and the iSCSI interface becomes unavailable, then the initiator logs multiple messages to the Windows Event Log. If multiple LUNs are configured for each target, the messages that the initiator generates can quickly fill the log.
    To avoid this situation, log out all connected initiators before bringing the target down for its scheduled downtime.
    Cannot write to a filesystem on the storage resource connected to the host.
    Filesystem is read-only.
    1. Verify that the registry values as set as described in Set registry values.
    2. Verify that the Microsoft iSCSI Initiator is configured as described in Windows host — Configuring to connect to an iSCSI interface