[gpfsug-discuss] LROC

[Sven Oehme]

Lroc only needs a StatCache object as it 'compacts' a full open File object
(maxFilesToCache) to a StatCache Object when it moves the content to the
LROC device.
therefore the only thing you really need to increase is maxStatCache on the
LROC node, but you still need maxFiles Objects, so leave that untouched and
just increas maxStat

Olaf's comment is important you need to make sure your manager nodes have
enough memory to hold tokens for all the objects you want to cache, but if
the memory is there and you have enough its well worth spend a lot of
memory on it and bump maxStatCache to a high number. i have tested
maxStatCache up to 16 million at some point per node, but if nodes with
this large amount of inodes crash or you try to shut them down you have
some delays , therefore i suggest you stay within a 1 or 2  million per
node and see how well it does and also if you get a significant gain.
i did help Bob to setup some monitoring for it so he can actually get
comparable stats, i suggest you setup Zimon and enable the Lroc sensors to
have real stats too , so you can see what benefits you get.

Sven

On Tue, Dec 20, 2016 at 8:13 PM Matt Weil <mweil at wustl.edu> wrote:

> as many as possible and both
>
> have maxFilesToCache 128000
>
> and maxStatCache 40000
>
> do these effect what sits on the LROC as well?  Are those to small?
> 1million seemed excessive.
>
> On 12/20/16 11:03 AM, Sven Oehme wrote:
>
> how much files do you want to cache ?
> and do you only want to cache metadata or also data associated to the
> files ?
>
> sven
>
>
>
> On Tue, Dec 20, 2016 at 5:35 PM Matt Weil <mweil at wustl.edu> wrote:
>
>
> https://www.ibm.com/developerworks/community/wikis/home?lang=en#!/wiki/General%20Parallel%20File%20System%20(GPFS)/page/Flash%20Storage
> <https://www.ibm.com/developerworks/community/wikis/home?lang=en#%21/wiki/General%20Parallel%20File%20System%20%28GPFS%29/page/Flash%20Storage>
>
> Hello all,
>
> Are there any tuning recommendations to get these to cache more metadata?
>
> Thanks
>
> Matt
>
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