As it should be evident from my recent posts, I have been playing with iSCSI and ZFS a lot lately. And the only OS in my home that I work on is OS-X on my laptops. And so started my quest to find a perfect iSCSI solution (based on OpenSolaris) for my OSX environment.
Apple does not provide any iSCSI initiator with Leopard, it’s been rumored that with Snow Leopard Apple might release iSCSI initiator. But till then there are at least 3 iSCSI initiators that exists for OS X users.
I have been told that iSCSI is a very complex specification and the success with a particular (initiator / target) combination depends upon how comprehensive they are (and how lucky you are). And that’s exactly what I found.
As my first test I just downloaded the globalSAN iSCSI initiator and used it to connect to the “iscsitgt” based target from my OpenSolaris 2008.11 Workstation. I was able to connect to the target the read performance was great, write kinda sucked but this was the first time I was playing with iSCSI and i liked the idea of block level access over Wi-Fi 
Then I started becoming inquisitive (greedy), and wanted to share multiple thin provisioned iSCSI devices to be used as TimeMachine, iTunes Library, iPhoto Library across my home network to be shared between multiple laptops. And for achieving that i started playing with advanced features like “Access Control List”, “CHAP Authentication” et. al.
So globalSAN iSCSI initiator was able to scan the target’s but as soon as I tried connecting to the target’s, the iSCSI initiator went into some sort of infinite loop and hung.
I came to know about this latest iSCSI implementation by Sun Microsystem which is written from scratch and is blazing fast. I had to try it and I did. Unfortunately with globalSAN iSCSI initiator I was unable to format the block devices.
Then I concentrated the next week getting access to different iSCSI initiators available for OSX and came across three:
- globalSAN (www.studionetworksolutions.com)
- Small-Tree (www.small-tree.com)
- Atto Xtend SAN (www.attotech.com)
I have not performed extensive tests (as of now) so I will just present my finding in form of a small table.
I would also like to state that compatibility table only represents the compatibility between these initiators with OpenSolaris based targets and does not talks about performance only compatibility.
As it’s visible from the table above Atto’s Xtend SAN was the only initiator that has so far been able to connect and access both the iSCSI subsystem’s with all variations (that I have tested so far). It’s also the one that costs the most ~200$ per seat, but hey it’s the only one which works so can’t complain.
If the requirements are not for using ACL’s or COMSTAR globalSAN has the best interface integration with the OSX preferences pane. On the other hand ATTO’s interface show’s age but also has many tunable options available.
