[ale] Slow NFS Speed?

[David Tomaschik]

On Thu, Sep 15, 2011 at 11:21 AM, Michael H. Warfield <mhw at wittsend.com> wrote:
> On Thu, 2011-09-15 at 10:43 -0400, David Tomaschik wrote:
>> At work, we have an OS X 10.5 NFS server with a Ubuntu Server 10.04
>> client.  (Among others.)  We're running backups via NFS using Amanda,
>> and the backups seem to be pegging at exactly 100Mbit/s.  Both
>> machines are connected via GigE, full-duplex.  (Confirmed via mii-tool
>> and system preferences.)
>
>> I can read from the storage array on the XServe at ~200MB/s via dd.
>> Additionally, Amanda can read from clients remotely (SSH transport) at
>> 400-500 Mbit/s, so it doesn't seem to be an issue with the backup
>> server.
>
> What's your "write speed", though (through both NFS and SSH).
> Unfortunately, NFS is notorious for this with write speeds often being
> significantly slower than read speeds (2:1 or even 3:1 not uncommon).
> NFS locking can have some impact.

The thing I probably failed to mention... we're reading from NFS to do
the backups.  (It is not the destination.)  Writing is to LTO4 tape.
We have written at >60MB/s to the tape, so that does not seem to be a
limiting factor.

>> I've tried tweaking NFS rsize with no noticeable impact.  Any other
>> hints to improve NFS performance?  Anyone with experience with OS X as
>> an NFS host?  Most of the information I find online is OS X as an NFS
>> client.
>
> That could be a real challenge.  Like I say, NFS has been known for this
> as long as I can remember and that goes all the way back to SunOS 3.x on
> 68020 processors in the 80's.  Do you know what version NFS is in use?
> Linux 2.6 supports versions 2, 3, and 4.  Is the NFS share being
> exported "SYNC" or "synchronous"?  That's the default behavior under
> Linux, afaik.  I don't know under OS X.  IAC, asynchronous can be much
> faster but can be riskier.

It is NFS3.  I don't think async vs sync would make much difference as
it is a read-heavy workload.  (At this point.)

> Might read this over, particularly the performance section.
>
> http://nfs.sourceforge.net/
>
>> --
>> David Tomaschik, RHCE, LPIC-1
>> System Administrator/Open Source Advocate
>> OpenPGP: 0x5DEA789B
>> http://systemoverlord.com
>> david at systemoverlord.com
>
> --
> Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw at WittsEnd.com
>   /\/\|=mhw=|\/\/          | (678) 463-0932 |  http://www.wittsend.com/mhw/
>   NIC whois: MHW9          | An optimist believes we live in the best of all
>  PGP Key: 0x674627FF        | possible worlds.  A pessimist is sure of it!




-- 
David Tomaschik, RHCE, LPIC-1
System Administrator/Open Source Advocate
OpenPGP: 0x5DEA789B
http://systemoverlord.com
david at systemoverlord.com