Kurt,
To clarify a bit further, the max_create_count is the maximum number of objects
that the MDS might precreate in a batch on an OST if it has a high create rate.
They are not necessarily _simultaneous_ creates.
In the recent IO-500 run, Cambridge sustained 1.78M creates/sec for 5 minutes
(on 24 MDTs + 24*11 OSTs, mind you), so this is not a very high limit.
On Jun 20, 2019, at 10:09, Degremont, Aurelien wrote:
>
> Hello Kurt,
>
> max_create_count is a tunable per OST. It controls how many object
> pre-creations could be done on each OST, by the MDT. If you set this to 0 for
> one OST, no additional object will be allocated there and no new file will
> have file stripes on it.
>
> With the appropriate hardware, Lustre can create much more than 20,000 files
> simultaneously.
>
> Aurélien
>
> Kurt Strosahl wrote on 2019-06-19 at 22:43:
>>
>> Good Afternoon,
>>
>> I'm in the process of testing a new lustre file system at 2.12, and in
>> going through the documentation I saw that to stop writes from going to the
>> system we now set the max_create_count to 0 on the mdt.
>>
>>I looked at that value on my system and the default seems to be 2, am
>> I correct in thinking that this is the maximum number of simultaneous
>> creates that can happen on an OST?
>>
>
Cheers, Andreas
--
Andreas Dilger
Principal Lustre Architect
Whamcloud
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