I'm trying to optimize my SAN. I just switched to using Jumbo Frames. My read speed has gone up drastically, but my write speed has gotten a lot worse.

It's very hard because I don't know how to tune it. The default settings on my initiator (Atto XtendSAN) are completely different than the Open-E iSCSI Enterprise's default settings.

What does Data Digest mean? Max Headers? MaxBurstLenght? Immediate Data? Is there a link to a website or a book or something I can read up and understand what this stuff means?

The target disks are formatted HFS+, all the clients are OS X, and I'm using a SAN program called MetaSAN. All this prevents me from using IOmeter, making it even harder.

Or could someone make a recommendation?

The target volumes are RAID 5 w/ 256k block size.

There are 4 client machines, and the target has a four-port 1gb nic. Everything is set to Jumbo Frames 9000 MTU. No bonding or anything like that yet.

The application is video editing. Any suggestions? Thanks.