[gpfsug-discuss] AFM and Placement Policies

Dean Hildebrand dhildeb at us.ibm.com
Fri Feb 26 18:58:47 GMT 2016


Hi Luke,

Cache eviction simply frees up space in the cache, but the inode/file is
always the same.  It does not delete and recreate the file in the cache.
This is why you can continue to view files in the cache namespace even if
they are evicted.

Dean Hildebrand
IBM Almaden Research Center




From:	Luke Raimbach <Luke.Raimbach at crick.ac.uk>
To:	gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Date:	02/26/2016 02:52 AM
Subject:	Re: [gpfsug-discuss] AFM and Placement Policies
Sent by:	gpfsug-discuss-bounces at spectrumscale.org



Hi Dean,

Thanks for this – I had hoped this was the case. However what I’m now
wondering is, if we operate the cache in independent-writer mode and the
new file was pushed back home (conforming to cache, then home placement
policies), then is subsequently evicted from the cache; if it needs to be
pulled back for local operations in the cache, will the cache cluster see
this file as “new” for the third time?

Cheers,
Luke.

From: gpfsug-discuss-bounces at spectrumscale.org [
mailto:gpfsug-discuss-bounces at spectrumscale.org] On Behalf Of Dean
Hildebrand
Sent: 24 February 2016 19:17
To: gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Cc: gpfsug main discussion list <gpfsug-discuss at gpfsug.org>
Subject: Re: [gpfsug-discuss] AFM and Placement Policies



Hi Luke,

The short answer is yes, when the file is created on the home, it is a
'brand new' creation that will conform to any and all new placement
policies that you set on the home site. So if you are using NFS in the
relationship, then it is simply created just like any other file is created
over NFS. The same goes when using GPFS to the home cluster...

Dean
IBM Almaden Research Center


Inactive hide details for Luke Raimbach ---02/24/2016 06:05:43 AM---Hi All,
I have two GPFS file systems (A and B) and an AFM SLuke Raimbach
---02/24/2016 06:05:43 AM---Hi All, I have two GPFS file systems (A and B)
and an AFM Single Writer relationship: /fsB/cache wri

From: Luke Raimbach <Luke.Raimbach at crick.ac.uk>
To: gpfsug main discussion list <gpfsug-discuss at gpfsug.org>
Date: 02/24/2016 06:05 AM
Subject: [gpfsug-discuss] AFM and Placement Policies
Sent by: gpfsug-discuss-bounces at spectrumscale.org




Hi All,

I have two GPFS file systems (A and B) and an AFM Single Writer
relationship: /fsB/cache writes back to /fsA/home

I have a placement policy which sets extended attributes on file creation
in /fsB/cache.

When I create a new file in /fsB/cache/new.file and it is pushed back by
AFM to /fsA/home/new.file, can the home fileset apply a different placement
policy to add or modify extended attributes? I guess the deeper question is
does each file system in this arrangement see the new.file as "new" in both
locations?

Cheers,
Luke.

Luke Raimbach​
Senior HPC Data and Storage Systems Engineer,
The Francis Crick Institute,
Gibbs Building,
215 Euston Road,
London NW1 2BE.

E: luke.raimbach at crick.ac.uk
W: www.crick.ac.uk

The Francis Crick Institute Limited is a registered charity in England and
Wales no. 1140062 and a company registered in England and Wales no.
06885462, with its registered office at 215 Euston Road, London NW1 2BE.
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The Francis Crick Institute Limited is a registered charity in England and
Wales no. 1140062 and a company registered in England and Wales no.
06885462, with its registered office at 215 Euston Road, London NW1 2BE.
_______________________________________________
gpfsug-discuss mailing list
gpfsug-discuss at spectrumscale.org
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