RedHat NFS client performance bug

Ed Martin ed.martin at iop.org
Wed Oct 30 11:18:00 CST 2002


Hi,

I've posted this to Red Hat web support, but I suspect I may get a better response here...

We are using Red Hat Linux as an NFS client on several PE servers talking to a Network Appliance f820 filer.

With Red Hat Advanced Server v2.1, and Red Hat Linux v7.3 clients with kernel-5 or later, and now with v7.2 using latest errata kernel 2.4.18-17, we sometimes get very poor performance.  The main measurable symptom appears to be that the rpc retransmit count increases rapidly.	This occurs especially with heavy i/o, e.g. manipulating big files.

I think we are seeing the bug Network Appliance list as number 72769.  If so they say that the problem is due to a packet reassembly bug in Linux.  Apparently due to be fixed in an RH errata kernel based on 2.4.19.  (I was told that Dave Miller at Red Hat knows about this).

We have tried various work arounds (using TCP rather than UDP, increasing several socket buffer settings), but none are completely satisfactory.  This problem occurs with PE1550, PE1650, PE2550, PE2650, though with a little variation (which may be network chipset/driver related).

Does anyone know anything about this?  And/or give me an indication of when a 2.4.19 errata kernel is likely to be released?  Any help would be very much appreciated.

Yours,

Ed



---
Ed Martin
Head of Systems Technology and Support
IOP Publishing Ltd
Dirac House, Temple Back
Bristol  BS1 6BE
ddi: +44 (0)117 930 1102
www:  http://www.iop.org



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