The Microsoft iSCSI initiator is a free download from the Microsoft web site. There are versions for x86 (32-bit), x64 (AMD64 and Intel EM64T) and IA64 (Intel Itanium) processors. Version 2.03 of the iSCSI initiator was used on all hosts for this report.
The iSCSI initiator installation process is the same relatively simple process for all the application hosts, and is wizard-based.
By default, the “Initiator Service” and “Software Initiator” features are checked. By default, the Microsoft MPIO multi-pathing feature is not checked. All the installations for this report used the MPIO feature and so this item was checked during installation.
If MPIO is not selected at installation, but desired later, the installer must be run again and the MPIO option selected. Beginning with Microsoft Windows Vista and the next release of Windows Server, MPIO is a feature that can be selected without re-installing.
A command-line utility, “iSCSIcli” is also installed that can be used to configure connections to iSCSI targets from the Windows Server host.
The release notes and user guide are installed onto the local host when the iSCSI initiator is installed. A few items from the release notes are worth mentioning here. Some of the restrictions listed here may change in future releases.
Dynamic disks on an iSCSI session are not supported. With Windows Vista and Windows Server Codename “Longhorn”, Dynamic Volumes are supported; however for best performance and redundancy, it is recommended that customers use basic disks or volumes in Windows combined with hardware RAID available in the storage arrays.
Note that the default iSCSI node name is generated from the Windows computer name. If the Windows computer name contains a character that would be invalid within an iSCSI node name, such as '_', then the Microsoft iSCSI Initiator service will convert the invalid character to '-'.
Both initiator and target CHAP secrets should be greater than or equal to 12 bytes, and less than or equal to 16 bytes if IPSec is not being used. It should be greater than 1 byte and less than or equal to 16 bytes if IPSec is being used.
The checked and retail versions of the Microsoft iSCSI Software Initiator will only install on retail version builds of Windows. There is no package that installs on checked builds of Windows.
Configure Microsoft iSCSI Initiator
After installation, the Microsoft iSCSI initiator is used to manage the iSCSI environment.
The general tab shows the initiator node name, which is the iSCSI Qualified Name (IQN).
The discovery tab provides the list of discovered iSCSI target portals available to this initiator. The target portal is the primary IP address of the iSCSI target solution. Some target solutions use a virtual IP address and some iSCSI target solutions provide the first actual IP address of the solution. If there are no target portals listed, they can be added by IP address or DNS name. In this case two iSCSI target portals have already been discovered. If there is an iSNS server available, it can provide all the iSCSI discovery information.
The targets tab provides the list of individual targets available to the iSCSI initiator. In this case, three targets are available to the iSCSI initiator.
To gain access to the target, the initiator must “Log On” to the target. If there is only one path to the target, there is only one step needed for log on.
If there are multiple-paths to the target, then each path must be described to the iSCSI initiator. This is done by enabling multi-path and clicking on the “Advanced” tab. The Log on process must be repeated for each separate path.
The advanced tab provides a drop-down box for all the possible source (initiator) IP addresses and a separate drop-down box for all possible target portal addresses. Some target solutions provide one virtual IP address for multi-path operations. In these cases, the target solution manages the actual paths and IP addresses internally. Other target solutions expose each available IP address that can be used for multi-path operations.
The administrator must select each desired combination of source IP address and target IP address.
Path Load-balancing and fail-over are configured here. During the target logon process, multiple paths can be configured by selecting different combinations of source and target IP addresses. After all the paths have been selected, the desired load-balancing or fail-over behavior can be configured. This behavior must be assigned for the session and the individual targets.
In this example, three paths have been specified for this target as shown by selecting “Details” from the targets window. For even load-balancing, select “Round Robin” for the session connections load balance policy.
For the target multi-pathing configuration, select the “Devices” tab from the targets window, then select “Advanced” to get to the MPIO selection tab. Select the load balance policy for each device.
Persistent Targets Tab
Targets can be configured to be persistent, which means that the connection to the target is automatically restored when the system reboots. If the targets are configured to be persistent, they appear in this dialog box.
Bound Volumes Tab
If a host service or application depends on the availability of an iSCSI volume, it should be “bound” so that the iSCSI service includes each “bound” volume as part of its initialization.