Niclas Sodergard writes:
> Hi,
>
> I'm trying to measure the performance of the NFS client and server in
> Solaris 10. I have two machines, both running Solaris 10u2. One
> machine is a x86 V20z and the other one is a UltraSparc Fire V240. The
> systems are interconnected using gigabit with a HP ProCurve switch in
> between (gigabit the whole way).
>
> Both have arrays connected to them. The V240 has a 6140 array with a
> zfs pool. I have measured the read and write performance locally to
> over 200MB/s. I've disabled the zil_update on this pool.
>
> The V20z has a generic sata array and I've neasured write performance
> above 100MB/s sustained.
>
> I've created a 8GB file on the 6140 and I'm now trying to read and
> write from the V20z using NFS. I've tried combinations of NFSv3 and
> NFSv4 but I get really poor performance. Reading the file using the
> following command:
>
> $ dd if=/mnt/bigfile of=/dev/null bs=128k
>
> gives me a reading speed of around 35-40MB/s which is disappointing.
> But now for the weird part
>
> $ dd if=/dev/zero of=/mnt/bigfile.1 bs=128k
>
> from the V20z to the V240 gives me a write speed of 80MB/s. So my
> problem is that I get reading speed of 40MB/s over NFS and with the
> same options I get writing speed of 80MB/s. I'm having a really hard
> time to understand this and I was hoping someone here could provide
> some light in this very dark tunnel.
>
> What could cause read speed to be so much slower than write?
>
This does not look extraordinary to me although, clearly it
could be bettern.
To write, you're pushing data out, presumably at the speed of
the network with NFS responses (ack) coming in stride.
To read, it's a request/response load. Send your request
wait for response. Because of the sequential streaming
access pattern, you should be hitting readahead codepath (in
the client client and server filesystem). That might not be
behaving optimally; so at times the network goes quiet while
a server side read is being braught in from disk.
-r
> cheers,
> Nickus
>
>
> --
> Have a look at my blog for sysadmins!
> http://aspiringsysadmin.com
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