[gpfsug-discuss] wanted...gpfs policy that places larger files onto a pool based on size

[Brian Marshall]

When creating a "fast tier" storage pool in a filesystem is the normal case
to create a placement policy that places all files in the fast tier and
migrates out old and large files?


Brian Marshall

On Mon, Oct 31, 2016 at 1:20 PM, Jez Tucker <jez.tucker at gpfsug.org> wrote:

> Hey Bryan
>
>   There was a previous RFE for path placement from the UG, but Yuri told
> me this was not techically possible as an inode has no knowledge about the
> parent dentry.  (IIRC).    You can see this in effect in the C API.  It is
> possible to work this out at kernel level, but it's so costly that it
> becomes non-viable at scale / performance.
>
> IBMers please chip in and expand if you will.
>
> Jez
>
>
> On 31/10/16 17:09, Bryan Banister wrote:
>
> The File Placement Policy that you are trying to set cannot use the size
> of the file to determine the placement of the file in a GPFS Storage Pool.
> This is because GPFS has no idea what the file size will be when the file
> is open()’d for writing.
>
>
>
> Hope that helps!
>
> -Bryan
>
>
>
> PS. I really wish that we could use a path for specifying data placement
> in a GPFS Pool, and not just the file name, owner, etc.  I’ll submit a RFE
> for this.
>
>
>
> *From:* gpfsug-discuss-bounces at spectrumscale.org [mailto:gpfsug-discuss-
> bounces at spectrumscale.org <gpfsug-discuss-bounces at spectrumscale.org>] *On
> Behalf Of *J. Eric Wonderley
> *Sent:* Monday, October 31, 2016 11:53 AM
> *To:* gpfsug main discussion list
> *Subject:* [gpfsug-discuss] wanted...gpfs policy that places larger files
> onto a pool based on size
>
>
>
> I wanted to do something like this...
>
>
> [root at cl001 ~]# cat /opt/gpfs/home.ply
> /*Failsafe migration of old small files back to spinning media pool(fc_8T)
> */
> RULE 'theshold' MIGRATE FROM POOL 'system' THRESHOLD(90,70)
> WEIGHT(ACCESS_TIME) TO POOL 'fc_8T'
> /*Write files larger than 16MB to pool called "fc_8T" */
> RULE 'bigfiles' SET POOL 'fc_8T' WHERE FILE_SIZE>16777216
> /*Move anything else to system pool */
> RULE 'default' SET POOL 'system'
>
> Apparently there is no happiness using FILE_SIZE in a placement policy:
> [root at cl001 ~]# mmchpolicy home /opt/gpfs/home.ply
> Error while validating policy `home.ply': rc=22:
> PCSQLERR: 'FILE_SIZE' is an unsupported or unknown attribute or variable
> name in this context.
> PCSQLCTX: at line 4 of 6: RULE 'bigfiles' SET POOL 'fc_8T' WHERE
> {{{FILE_SIZE}}}>16777216
> runRemoteCommand_v2: cl002.cl.arc.internal: tschpolicy /dev/home
> /var/mmfs/tmp/tspolicyFile.mmchpolicy.113372 -t home.ply   failed.
> mmchpolicy: Command failed. Examine previous error messages to determine
> cause.
>
> Can anyone suggest a way to accomplish this using policy?
>
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