nfsd server cache flooded, try to increase nfsrc_floodlevel

[Harald Schmalzbauer]

 Bezüglich Rick Macklem's Nachricht vom 25.07.2014 13:14 (localtime):
> Harald Schmalzbauer wrote:
>> Bezüglich Rick Macklem's Nachricht vom 25.07.2014 02:14 (localtime):
>>> Harald Schmalzbauer wrote:
>>>> Bezüglich Rick Macklem's Nachricht vom 08.08.2013 14:20
>>>> (localtime):
>>>>> Lars Eggert wrote:
>>>>>> Hi,
>>>>>>
>>>>>> every few days or so, my -STABLE NFS server (v3 and v4) gets
>>>>>> wedged
>>>>>> with a ton of messages about "nfsd server cache flooded, try to
>>>>>> increase nfsrc_floodlevel" in the log, and nfsstat shows TCPPeak
>>>>>> at
>>>>>> 16385. It requires a reboot to unwedge, restarting the server
>>>>>> does
>>>>>> not help.
>>>>>>
>>>>>> …
>> IMHO such a setup shouldn't require manual tuning and I consider this
>> as
>> a really urgent problem!
>> Whatever causes the server to lock up is strongly required to be
>> fixed
>> for next release,
>> otherwise the shipped implementation of NFS is not really suitable
>> for
>> production environment and needs a warning message when enabled.
>> The impact of this failure forces admins to change the operation
>> system
>> in order to get a core service back into operation.
>> The importance is, that I don't suffer from weaker performance or
>> lags/delays, but my server stops NFS completely and only a reboot
>> solves
>> this situation.
>>
> Btw, you can increase vfs.nfsd.tcphighwater on the fly when it wedges
> and avoid having to reboot.
One suggestion: If raising vfs.nfsd.tcphighwater at runtime solves the
locked nfsserver (which I thought I have tried, but I'm not sure any
more), maybe the log message should reflect that. My first guess was to
look for a systcl named 'nfsrc_floodlevel'. If the log message makes
more sense to contain nfsrc_floodlevel instead of tcphighwater, the
latter should be metioned in the man page anyway.

If the problem is solvable without rebooting, it's a cosmetic problem
IMHO, not that serious show stopper I considered at first. Evereything
but a reboot is fine ;-)

Thanks,

-Harry




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