[gpfsug-discuss] Metadata block size

Asgeir Storesund Nilsen asgeir at twingine.no
Wed Feb 12 06:56:19 GMT 2014


Orlando,

Thanks, that proved to be exactly the cause of my hiccups.  I only
realized this after reading some more in the mmcrfs manual page and
source.

But has GPFS' behavior on this actually changed between 3.5.0.0 and
3.5.0.7, or is it only mmcrfs which has become more strict in
enforcing what tscrfs actually does?

Asgeir

On Wed, Feb 12, 2014 at 12:34 AM, Orlando Richards
<orlando.richards at ed.ac.uk> wrote:
> Hi Asgeir,
>
> From memory, you need to have the data disks going in as a separate storage pool to have the split block size - so metadata disks in the "system" pool and data disks in , say, the "data" pool. Have you got that split here?
>
> ----
> Orlando
>
> Sent from my phone
>
>> On 11 Feb 2014, at 17:23, Asgeir Storesund Nilsen <asgeir at twingine.no> wrote:
>>
>> Hi,
>>
>> I want to create a file system with 16MB for data blocks and 256k for metadata blocks.  Under filesystem version 13.01 (3.5.0.0) this worked just fine, even when upgrading GPFS later.
>>
>> However, for a filesystem created with version 13.23 (3.5.0.7), if I specify both data and metadata block sizes, the metadata block size applies for both.  If I do not specify metadata block size, the data block size (-B) is used for both.
>>
>> This has a detrimental impact on our metadataOnly NSDs, as they fill up pretty quickly.
>>
>>
>> Are any of you aware of updates / bugs in GPFS that might help explain and alleviate this issue?  Any hints would be appreciated.
>>
>> Regards,
>> Asgeir
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