On Thu, 6 Aug 2009, Thomas Georgiou wrote:
However, if the data is cached on the osol server, then I can get
80MB/s over iscsi (for 400MB and dropping caches on the initiator).
It drops to 20MB/s for sustained data transfer (8GB). However, for
cached data on the linux iscsi target, I can get >110MB/s.
It is pretty exciting getting better than wire-speed with Linux!
How are you testing iSCSI performance? What do your data files look
like? What are the sizes of the files, and how many are there?
Perhaps your performance is getting killed by the zfs performance bugs
illustrated by the script at
"http://www.simplesystems.org/users/bfriesen/zfs-discuss/zfs-cache-test.ksh";.
Many people on the zfs-discuss list ran this script and did notice
that the second access to a large collection of these medium sized
files was extremely slow due to zfs failing to use prefetch. Even the
first access is much slower than the hardware supports.
Bob
--
Bob Friesenhahn
bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
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