On Aug 3, 2010, at 12:13 PM, Roch Bourbonnais <roch.bourbonn...@sun.com> wrote:
> > Le 27 mai 2010 à 07:03, Brent Jones a écrit : > >> On Wed, May 26, 2010 at 5:08 AM, Matt Connolly >> <matt.connolly...@gmail.com> wrote: >>> I've set up an iScsi volume on OpenSolaris (snv_134) with these commands: >>> >>> sh-4.0# zfs create rpool/iscsi >>> sh-4.0# zfs set shareiscsi=on rpool/iscsi >>> sh-4.0# zfs create -s -V 10g rpool/iscsi/test >>> >>> The underlying zpool is a mirror of two SATA drives. I'm connecting from a >>> Mac client with global SAN initiator software, connected via Gigabit LAN. >>> It connects fine, and I've initialiased a mac format volume on that iScsi >>> volume. >>> >>> Performance, however, is terribly slow, about 10 times slower than an SMB >>> share on the same pool. I expected it would be very similar, if not faster >>> than SMB. >>> >>> Here's my test results copying 3GB data: >>> >>> iScsi: 44m01s 1.185MB/s >>> SMB share: 4m27 11.73MB/s >>> >>> Reading (the same 3GB) is also worse than SMB, but only by a factor of >>> about 3: >>> >>> iScsi: 4m36 11.34MB/s >>> SMB share: 1m45 29.81MB/s >>> > > <cleaning up some old mail> > > Not unexpected. Filesystems have readahead code to prefetch enough to cover > the latency of the read request. iSCSI only responds to the request. > Put a filesystem on top of iscsi and try again. > > For writes, iSCSI is synchronous and SMB is not. It may be with ZFS, but iSCSI is neither synchronous nor asynchronous is is simply SCSI over IP. It is the application using the iSCSI protocol that determines whether it is synchronous, issue a flush after write, or asynchronous, wait until target flushes. I think the ZFS developers didn't quite understand that and wanted strict guidelines like NFS has, but iSCSI doesn't have those, it is a lower level protocol than NFS is, so they forced guidelines on it and violated the standard. -Ross _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
