[DRBD-user] Possible issue with DRBD and KNFSD

Lars Ellenberg lars.ellenberg at linbit.com
Fri May 25 13:34:28 CEST 2007

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

On Fri, May 25, 2007 at 12:41:15AM -0700, John Frisk wrote:
> Team,
> I have been working with the NFS folks for a bit now
> and am experiencing something strange which causes NFS
> clients to hang when attempting to use
> heartbeat/drbd/knfsd as a HA NFS server.  I don't
> believe this is a NFS issue any longer.  
> Setup:
> Machine A: primary drbd and HA machine (SMP machine)
> Machine B: secondary drbd and HA machine (UP machine)
> Machine C: NFS client using bonnie++ as a test for I/O
> activity ( -f -s 100 -n 1 -r 0 are the parameters )
> All machines are Debian 4.0 etch with vanilla
> 2.6.22-rc2 kernel + known NFS issues patched

> So I have been asking myself "What is the difference
> between machine A and B that would cause the issue
> only on machine A".  The network adapters on both A &
> B are realtek r8169 style adapters.  The biggest
> difference I can think of is machine A is an SMP
> machine Athlon 64 X2 (running on a i386 kernel due to
> support issues with the 64bit kernel) while machine B
> is an older Athlon slot A processor.

lower level io-subsystem differs?
available RAM differs?

> I have attached a triggered sysrq from machine

not useful here.

look at /proc/drbd,
and tell us what is there, when your nfs-client hangs.

does generating local io
(or "sync" or "emergency sync" via sysrq)
on the Primary help?
on the Secondary?

maybe you can also watch with wireshark and find some
"interessting" behaviour (please, I'm not interessted
in any unprocessed dump files; this is just a suggestion
for a tool you might use to further nail down what happens).

: Lars Ellenberg                            Tel +43-1-8178292-0  :
: LINBIT Information Technologies GmbH      Fax +43-1-8178292-82 :
: Vivenotgasse 48, A-1120 Vienna/Europe    http://www.linbit.com :
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