> From: [email protected] [mailto:discuss- > [email protected]] On Behalf Of Jonathan B Bayer > > I then did a simple test, copying a 4.3 gig ISO to each volume. I did this two > times, and timed the second copy; this way the overhead of allocating space > was eliminated. > > The results puzzled me: > > NFS: 5:08 > iSCSI: 5:54
Unless I miss my guess, it takes the same amount of time either way, but your NFS client is buffering the writes and reporting completion sooner than actual completion. However, extremely suspicious: Your NFS speed is 111Mbit/sec, while your iscsi speed is 97Mbit/sec. Are you 100% certain you are getting Gigabit speeds on all your wires & switches, client and server? My explanation makes perfect sense as long as there's something limiting your wire speed to 100Mbit. If you don't have something limiting you to 100Mbit ... Well ... you're only getting 100Mbit, and that is unnaturally slow for either protocol. PS. I performed this exact same test before, and I found there was no performance difference between NFS and iSCSI. Interested to see if your results agree. PPS. In either NFS or iSCSI, you're likely to be limited by ZIL performance on the ZFS side, because they both perform sync-mode writes by default. You could disable your ZIL, or add SSD log devices to the server... Or hang it all, and just do read-performance testing instead. I would suggest you'll get better (more accurate comparison of iscsi vs nfs) results reading from the server instead of writing. _______________________________________________ Discuss mailing list [email protected] https://lists.lopsa.org/cgi-bin/mailman/listinfo/discuss This list provided by the League of Professional System Administrators http://lopsa.org/
