Best iSCSI setup for FreeNAS 8.3

[jlin]

Hello, I am looking to set up a fresh iSCSI server with 8.3. I am aware of some of the differences between 8.2 and 8.3, but I am having trouble sleuthing out what is supposed to be the best method. I have read about file versus device extents, is it now correct that a device extent is supposed to work well and there is no longer a significant sync penalty?

I may have the option to go all SSD to fix potential performance problems but more space with some fast disks would be preferred if it does not cause undue performance hits to do so.

 

[jgreco]

Um, good question...

Writes to a file extent on a RAIDZ2 with iSCSI from an ESXi initiator, 39.8MB/sec. Writes to a zvol ZFS device on the same exact setup, 35.8MB/sec. sync=standard on both of those. Writes to a zvol ZFS device with sync=disabled, just a shade slower, actually.

Note that the system in question has been tuned for iSCSI responsiveness in line with what I outline in bug 1531, but we're not actively using it for iSCSI at this time, so this was done on empty VMFS datastores from the ESXi command line.

Looks like you can pick your preferred method for doing iSCSI and not worry about it too horribly much. Oh and yes that's on 8.3 with a v28 pool. Your mileage will vary with 8.2 or other versions.