[OpenIndiana-discuss] NAS R/W performance puzzle

Bob Friesenhahn bfriesen at simple.dallas.tx.us
Mon Mar 24 17:41:55 UTC 2014

On Sun, 23 Mar 2014, Reginald Beardsley wrote:

> Some casual testing has turned up a bit of a puzzle.
> I've got an N40L w/ 4x2TB ST2000DM001 in a RAIDZ2 pool with 4 GB of ECC DRAM running oi151a7.  This is NFS mounted to a Z400 running Solaris 10 (last Sun release U7?)
> On the N40L I get 125 MB/s write and 250 MB/s read for 6.5 GB using /dev/zero & /dev/null w/ bs=65536.
> On the Z400 using NFS I get 50 MB/s write but only 10-20 MB/s read for the same operations.  Both systems and the network are unloaded.  Write speed over NFS is quite consistent, but the read varies by 2x.
> Can anyone suggest why the NFS read is so much slower than the NFS write?  I'm baffled by the relative speed of the R/W operations reversing like that.   The only reasons I can think of are some issue in the network stack or  NFS implementations.

You have not really told us very much.  What mechanism/approach are 
you using to measure client NFS read and write performance on the 
Solaris 10 system?

Bob Friesenhahn
bfriesen at simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/

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