[zfs-discuss] Poor read/write performance when using ZFS iSCSI target

Maurice Volaski
Tue, 11 Nov 2008 00:42:32 -0000

I was wondering if you ever figured this out or if you''ve reported
it. I''m testing a configuration using snv_99 and am seeing similar
behavior.


>I want to take advantage of the iSCSI target support in the latest
>release (svn_91) of OpenSolaris, and I''m running into some
>performance problems when reading/writing from/to my target. I''m
>including as much detail as I can so bear with me here...
>
>I''ve built an x86 OpenSolaris server (Intel Xeon running NV_91)
with
>a zpool of 15 750GB SATA disks, of which I''ve created and exported
a
>ZFS Volume with the shareiscsi=on property set to generate an iSCSI
>target.
>
>My problem is, when I connect to this target from any initiator
>(tested with both Linux 2.6 and OpenSolaris NV_91 SPARC and x86),
>the read/write speed is dreadful (~ 3 megabytes / second!).  When I
>test read/write performance locally with the backing pool, I have
>excellent speeds. The same can be said when I use services such as
>NFS and FTP to move files between other hosts on the network and the
>volume I am exporting as a Target. When doing this I have achieved
>the near-Gigabit speeds I expect, which has me thinking this isn''t
a
>network problem of some sort (I''ve already disabled the Neagle
>algorithm if you''re wondering). It''s not until I add the
iSCSI
>target to the stack that the speeds go south, so I am concerned that
>I may be missing something in configuration of the target.
>

--

Maurice Volaski, mvolaski at aecom.yu.edu
Computing Support, Rose F. Kennedy Center
Albert Einstein College of Medicine of Yeshiva University