On Fri, Jun 26, 2009 at 6:04 PM, Bob Friesenhahn<bfrie...@simple.dallas.tx.us> wrote: > On Fri, 26 Jun 2009, Scott Meilicke wrote: > >> I ran the RealLife iometer profile on NFS based storage (vs. SW iSCSI), >> and got nearly identical results to having the disks on iSCSI: > > Both of them are using TCP to access the server. > >> So it appears NFS is doing syncs, while iSCSI is not (See my earlier zpool >> iostat data for iSCSI). Isn't this what we expect, because NFS does syncs, >> while iSCSI does not (assumed)? > > If iSCSI does not do syncs (presumably it should when a cache flush is > requested) then NFS is safer in case the server crashes and reboots. > > Bob > -- > Bob Friesenhahn > bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ > GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss >
I'll chime in here as I've had experience with this subject as well (ZFS NFS/iSCSI). It depends on your NFS client! I was using the FreeBSD NFSv3 client, which by default does an fsync() for every NFS block (8KB afaik). However, I changed the source and recompile so it would only fsync() on file close or I believe after 5MB. I went from 3MB/sec, to over 100MB/sec after my change. I detailed my struggle here: http://www.brentrjones.com/?p=29 As for iSCSI, I am currently benchmarking the COMSTAR iSCSI target. I previously used the old iscsitgtd framework with ZFS. Previously I would get about 35-40MB/sec. My initial testing with the new COMSTAR iSCSI target is not revealing any substantial performance increase at all. I've tried zvol based lu's, and file based lu's with no perceived performance difference at all. The iSCSI target is an X4540, 64GB RAM, and 48x 1TB disks configured with 8 vdevs with 5-6 disks each. No SSD, ZIL enabled. My NFS performance is now over 100MB/sec, I can get over 100MB/sec with CIFS as well. However, my iSCSI performance is still rather low for the hardware. It is a standard GigE network, currently jumbo frames are disabled, when I get some time I may make a VLAN with jumbo frames enabled and see if that changes anything at all (not likely). I am CC'ing the storage-discuss group as well for coverage as this covers ZFS, and storage. If anyone has some thoughts, code, or tests, I can run them on my X4540's and see how it goes. Thanks -- Brent Jones br...@servuhome.net _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
