Hello there!
I'm new to FreeNAS, but I've been in the storage and networking infrastructure industry for a couple decades. I've been able to set up a Dell PowerEdge R815 with 72TB of NetApp storage behind it in a RAIDZ3, and share a few ZVOLs to my 10GbE SAN as iSCSI shares. I'm happy with the performance from my other Dell boxes, sustaining a little better than 300MB/sec on writes and 600MB/sec on reads on one of the ZVOL partitions in the NetApp shelf, so we're good there so far.
However, I can't figure out how to obtain a usable performance on my Mac Pro running 10.11 with XtendSAN to one of these same ZVOLs, formatted as "OS X Extended". AJA disk test indicates that the read performance is good, about 500MB/sec, which is fine. However, the best I can consistently sustain on writes is about 75MB/sec, or a quarter of what Windows can do.
I suspect that it's a write caching problem, but I can't find any reliable information on dealing with write cache configuration in OS X. I see references to disabling write caching on USB devices, but I have the opposite problem -- OS X will let me eject the device, so that tells me that OS X considers the iSCSI share as a removable device, and so write caching should be configured conservatively. I've played around with Storage / Pools / Edit Zvol, forcing the "Sync" option on the ZVOL to "Disabled", switched to gzip compression, and of course dedupe is off, but nothing has helped.
So, if you're in an environment that can sustain 300-500MB/sec, and you want to make backups from your Mac (ideally I would like to use Time Machine, but I also have a license for Retrospect 15 on the Mac), what are the best practices? AFP is being deprecated, and SMB is single-threaded, and on the flipside, iSCSI works beautifully on my Dell boxes, so iSCSI makes sense, but maybe not if it's this terrible on write performance under OS X.
Thanks in advance!
Chris
I'm new to FreeNAS, but I've been in the storage and networking infrastructure industry for a couple decades. I've been able to set up a Dell PowerEdge R815 with 72TB of NetApp storage behind it in a RAIDZ3, and share a few ZVOLs to my 10GbE SAN as iSCSI shares. I'm happy with the performance from my other Dell boxes, sustaining a little better than 300MB/sec on writes and 600MB/sec on reads on one of the ZVOL partitions in the NetApp shelf, so we're good there so far.
However, I can't figure out how to obtain a usable performance on my Mac Pro running 10.11 with XtendSAN to one of these same ZVOLs, formatted as "OS X Extended". AJA disk test indicates that the read performance is good, about 500MB/sec, which is fine. However, the best I can consistently sustain on writes is about 75MB/sec, or a quarter of what Windows can do.
I suspect that it's a write caching problem, but I can't find any reliable information on dealing with write cache configuration in OS X. I see references to disabling write caching on USB devices, but I have the opposite problem -- OS X will let me eject the device, so that tells me that OS X considers the iSCSI share as a removable device, and so write caching should be configured conservatively. I've played around with Storage / Pools / Edit Zvol, forcing the "Sync" option on the ZVOL to "Disabled", switched to gzip compression, and of course dedupe is off, but nothing has helped.
So, if you're in an environment that can sustain 300-500MB/sec, and you want to make backups from your Mac (ideally I would like to use Time Machine, but I also have a license for Retrospect 15 on the Mac), what are the best practices? AFP is being deprecated, and SMB is single-threaded, and on the flipside, iSCSI works beautifully on my Dell boxes, so iSCSI makes sense, but maybe not if it's this terrible on write performance under OS X.
Thanks in advance!
Chris