Thanks, lufu. It's great to get a comparison point!

Yeah, there probably is something wrong with my iSCSI set up.

Part of the problem is that I am using a software RAID 5 using only 3 drives (2+parity).

Not using jumbo frames, either.

Both sides are also using pentium 4 chips with netburst and only one thread of sqlio (since the initiator side has only one cpu core). Shouldn't be THAT slow, though. I tried tuning the iSCSI target daemon settings, but I haven't got much better results.

Part of my whole point was to see how well FC works when just working from cache, since you could load up a 1U server with 100GB of cache instead of investing in lots of SAS drives.

BTW, I really like the Areca controllers. That's what we've used in our setup.

Here are the 4K random write IO results from a single drive hooked up to a 3ware controller with 512MB of raid cache and 2GB of system cache exported via 4Gb FC:


It makes sense that the smaller test files are so high performance and the larger ones are so much slower, since we're limited to a single sata drive on the backend, so we'd be lucky to get more than 60MB/s sustained.