On Sun, 21 Feb 2010, Fai Cheng wrote:
The issue is while i transfer large files via iSCSI (COMSTAR) or
CIFS (from OSX 10.6 or Windows 7) the transfer performance is not
stable, sometime it can goes up to 100 MB/s and sometime drop down
to 1-2 MB/s
I used iperf to test the network performance, and the network performance is
stable.
This may be a read stall while a transaction group is written. Your
gigabit ethernet can transfer quite a lot of data, and it is cached in
RAM until the next TXG is written. This is what I saw with Perfmeter
when this problem occurs:
http://www.simplesystems.org/users/bfriesen/zfs-discuss/perfmeter-stalls.png
If real-time writes are important to you, then you should investigate
the zfs:zfs_arc_max parameter in /etc/system combined with a
controller card with battery backed cache.
Bob
--
Bob Friesenhahn
bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
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