iSCSI is a standard that uses the familiar SCSI storage command set but sends it over Ethernet. The technology allows for convenient shared storage over fast TCP networking such as the common Gigabit Ethernet and now faster flavors in the market such as 10Gigabit Ethernet.
The technology calls for a initiator on the client side and then a target on the storage side. There was talk that Apple would provide both.
However, as we may remember, Apple's shifting of OS X and QA (quality assurance) engineers over to the iPhone earlier this year caused a backlog of bug reports and more importantly, a slowdown for fixes for the bugs. Some features expected in the initial Leopard release (and seen on pre-Golden Master Builds) didn't make the first cut. And that included iSCSI support.
Still, there are a number of options from developers. There are several initiators on the market. But I haven't heard much noise about the target side (other than companies targeting the Mac market with iSCSI controllers that come with Xserve RAID attached, such as these DNFStorage StorMacX servers).
Here are the initiators:
Studio Network Solutions offers Version 3.0 globalSAN SCSI Initiator for OS X. The software is a free download and not a "timed evaluation or feature-locked."
The initiator supports CHAP, persistent targets, SLPv2 and Multiple Connections per Session. Version 3.0 is a Universal Application, for Intel- and PowerPC-based Mac computers.
Translation: CHAP is the Challenge-Handshake Authentication Protocol and SLP is a standard for discovery over a network.
Longtime Mac storage vendor ATTO Technology offers a commercial initiator called the Xtend SAN iSCSI Initiator for Mac OS X Version 3.10. It supports Leopard and costs $195.
According to ATTO, the software supports the latest iSCSI standards as well as iSCSI error handling and recovery, login redirect, CHAP, and iSNS clients (another standard for discovering and managing iSCSI and Fibre Channel devices).
ARDIS Technologies has a iSCSI initiator, but I'm unsure of its cost. A 30-day evaluation version is available.
According to a spec sheet on the related DynamicDrivePool site, the driver is compatible with Panther and Tiger; supports CHAP authentication, iSCSI redirect and immediate data; as well as persistent login. For those readers hot to dive into iSCSI, perhaps take a look at Brad Laue's blog. It's an interesting post and thread about his experience with Time Machine over iSCSI. He found that the "iSCSI angle is too risky for now."
For more posts on the Leopard Update, check out: