To use iSCSI storage on the server, one or more iSCSI LUs (LUs) must be defined. iSCSI LUs are blocks of SCSI storage that are accessed through iSCSI targets. iSCSI targets can be found through an iSNS database or through a target portal. After an iSCSI target has been found, an Initiator running on a Windows server can access the LU as a “local disk” through its target. Security mechanisms can be used to prevent unauthorized access to iSCSI targets.
On the server, iSCSI LUs are just regular files residing on a file system. As a result, iSCSI benefits from file system management functions provided by the server, such as NVRAM logging, snapshots, and quotas.
The contents of the iSCSI LUs are managed on the Windows server. Where the server views the LUs as files containing raw data, Windows views each iSCSI target as a logical disk, and manages it as a file system volume (typically using NTFS). As a result, individual files inside of the iSCSI LUs can only be accessed from the Windows server. Server services, such as snapshots, only operate on entire NTFS volumes and not on individual files.
iSCSI MPIO (Multi-path Input/Output) uses redundant paths to create logical “paths” between the client and iSCSI storage. In the event that one or more of these components fails, causing the path to fail, multi-pathing logic uses an alternate path so that applications can still access their data.
For example, clients with more than one Ethernet connection can use logical paths to establish a multi-path connection to an iSCSI target on the server. Redundant paths mean that iSCSI sessions can continue uninterrupted in the event of the failure of a particular path. An iSCSI MPIO connection can also be used to load-balance communication to boost performance.
If you intend to use an offload engine, make sure it is compatible with Microsoft multi-path and load-balancing.
iSCSI MPIO is supported by Microsoft iSCSI Initiator 2.0.
iSCSI access statistics
Statistics are available to monitor iSCSI activity since the server was last started or its statistics were reset. The statistics are updated every 10 seconds.
To enable iSCSI capability:
- Enter an iSCSI license key.
- Enable the iSCSI service.
Supported iSCSI initiators
The server currently supports the following iSCSI initiators:
- Microsoft iSCSI Initiator version 1.06 (or later).
- Microsoft iSCSI Initiator version 2.05 (provides MPIO support).
- Linux iSCSI initiator versions 3.4.2, 3.6.2, 3.6.3, and 184.108.40.206 (available from the Linux iSCSI project on SourceForge).
- Solaris 10 U2 (64 bit) native initiator, iscsiadm v1.0.
- Macintosh (OS X 10.4 Tiger) ATTO Xtend SAN v3.10.
- Open iSCSI version 2.0.865.
The server currently supports the use of the Alacritech SES1001T and SES1001F offload engines when used with the Microsoft iSCSI initiator version 1.06 or later. Check with your Hitachi Vantara representative for the latest list of supported offload engines.