[Lustre-devel] question about ldlm_server_glimpse_ast
spitzcor at cray.com
Fri Apr 30 12:25:54 PDT 2010
Increasing ldlm_timeout has no effect whatsoever if adaptive timeouts are
enabled. See bug 22569. I suggest that you tune up at_min instead.
Oleg Drokin wrote:
> On Apr 30, 2010, at 9:00 AM, John Hammond wrote:
>> I tested a patch which set rq_no_resend = 0 for glimpses, and found that
>> clients only had about 6 seconds to reply before eviction. Since
>> eviction creates the possibility for data loss, a 6 second timeout was
>> deemed too short for production. (With the patch applied, it was easy
>> for me to create cases where data was indeed lost.) I was also able to
> Please note that the 6 second timeout is in fact common ldlm_timeout and it's
> not just glimpses that are bound by this value.
> any ldlm callbacks are required to reply withing this time, so if your
> network can have delays of more then this much, you need to consider
> increasing ldlm_timeout value (/proc/sys/lustre/ldlm_timeout).
> On the other hand if you have a packet loss issue, even if
> resending of glimpse ASTs would be present, we don't currently resend
> other ASTs so the situation still has a potential for evictions
> with subsequent possible data loss.
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