[Lustre-discuss] lock timeouts and OST evictions on 1.4 server - 1.6 client system.

[Oleg Drokin]

Hello!

On Feb 10, 2009, at 12:11 PM, Simon Kelley wrote:
>>> We are also seeing some userspace file operations fail with the  
>>> error
>>> "No locks available". These don't generate any logging on the  
>>> client  so
>>> I don't have exact timing. It's possible that they are associated  
>>> with
>>> further "### lock callback timer expired" server logs.
>> This error code typically means an application attempting to do  
>> some i/ o and Lustre
>> has no lock for the i/o area for some reason anymore (it is  
>> normally  obtained
>> once read or write path is entered), and that could be related to   
>> evictions too
>> (locks are revoked at eviction time).
> I should have mentioned that we are also seeing many errors of the  
> form "LustreError: 19842:0:(ldlm_lockd.c:1078:ldlm_handle_cancel())  
> received cancel for unknown lock cookie." Checking back, these would  
> seem to pre-date the introduction of 1.6 clients and even after we  
> upgraded clients I can see them associated with both 1.4 and 1.6  
> clients. They may indicate something else relevant about the  
> filesystems or workload.

Hm, that means clients hold some locks that server does not believe  
thy have, which is pretty strange.
Or it just does not recognize the lock released by client and later  
releases the client.
If you have a complete kernel log of the event, that might be useful  
to see the sequence of events.
I assume you do not have flaky network and your clients do not  
reconnect all the time to the servers
with messages in logs like 'changed handle from X to Y; copying, but  
this may foreshadow disaster',
which would be a different bug no longer present in 1.6.6, too.

Bye,
     Oleg