[gpfsug-discuss] GPFS - pagepool data protection?

[Dean Hildebrand]

Hi Paul,

GPFS correctly implements POSIX semantics and NFS close-to-open semantics.
Its a little complicated, but effectively what this means is that when the
application issues certain calls to ensure data/metadata is "stable" (e.g.,
fsync), then it is guaranteed to be stable.  It also controls ordering
between nodes among many other things.  As part of making sure data is
stable, the GPFS recovery journal is used in a variety of instances.

With VMWare ESX using NFS to GPFS, then the same thing occurs, except the
situation is even more simple since every write request will have the
'stable' flag set, ensuring it does writethrough to the storage system.

Dean Hildebrand
IBM Almaden Research Center




From:	Pavel Pokorny <pavel.pokorny at datera.cz>
To:	gpfsug-discuss at gpfsug.org
Date:	11/07/2014 03:15 AM
Subject:	[gpfsug-discuss] GPFS - pagepool data protection?
Sent by:	gpfsug-discuss-bounces at gpfsug.org



Hello to all,
I would like to ask question about pagepool and protection of data written
through pagepool.
Is there a possibility of loosing data written to GPFS in situation that
data are stored in pagepool but still not written to disks?
I think that for regular file system work this can be solved using GPFS
journal. What about using GPFS as a NFS store for VMware datastores?
Thank you for your answers,
Pavel
--
Ing. Pavel Pokorný
DATERA s.r.o. | Ovocný trh 580/2 | Praha | Czech Republic
www.datera.cz | Mobil: +420 602 357 194 | E-mail: pavel.pokorny at datera.cz
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