XFS Performance on NetApp
Does anybody have a report how XFS behaves on a NetApp storage with thin provisioning? They have a completely "weird" storage, their WAFL (write anywhere file layout) together with deduplication and other things make me think the best is to not-at-all specify any "performance options" in mkfs/mount, like sunit/swidth or largeio, swalloc, etc.
Does someone have information on that?
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mit freundlichen Grüssen, Michael Monnerie, Ing. BSc it-management Internet Services http://proteger.at [gesprochen: Prot-e-schee] Tel: 0660 / 415 65 31 ****** Radiointerview zum Thema Spam ****** http://www.it-podcast.at/archiv.html#podcast-100716 // Wir haben im Moment zwei Häuser zu verkaufen: // http://zmi.at/langegg/ // http://zmi.at/haus2009/
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Quoted 7 lines · Michael Monnerie
Does anybody have a report how XFS behaves on a NetApp storage with thin provisioning? They have a completely "weird" storage, their WAFL (write anywhere file layout) together with deduplication and other things make me think the best is to not-at-all specify any "performance options" in mkfs/mount, like sunit/swidth or largeio, swalloc, etc.
Does someone have information on that?
Not about the Netapp as such.
However, as a general rule thin provisioned storage will have unpredictable performance characteristics as the block number/physical location correlation is meaningless.
e.g. because the log is one of the first things written to a thinly provisioned volume during mkfs, it is unlikely to be physically located in the middle of the volume. Indeed, there's no guarantee that it will even be on the same spindles as the rest of the filesystem, and it may be sharing spindles with some other thin volume....
So, you are right in assuming that it is best not to tune your filesystem to a specific physical geometry because there generally isn't one for thinly provisioned volumes. However, options that reduce filesystem fragmentation (e.g. allocsize) still have value in keeping the amount of metadata and ptotential seeks down...
Cheers,
Dave.
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Dave Chinner [email protected] _______________________________________________ xfs mailing list [email protected] http://oss.sgi.com/mailman/listinfo/xfs
Quoted 3 lines · On Mittwoch, 27. Oktober 2010 Dave Chinner wrote:
However, options that
reduce filesystem fragmentation (e.g. allocsize) still have value in keeping the amount of metadata and ptotential seeks down...
Yes, but for NetApp: maybe. With this whole deduplication thingy, I wonder if even such a simple assumption is true. And then some people make a snapshot every hour, whichmeans your log will wander around on the storage anyway. So it's best to "just use it".
Another thing just crosses my mind: on a thin provisioned system, would the TRIM command be useful? Do such storages recognise this command? It would be very clever, I think. Let's say you run xfs_fsr, that would allow the upper layer to relaim unused space. Would that be the storage or XenServer/VMware which needs to understand this command?
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mit freundlichen Grüssen, Michael Monnerie, Ing. BSc it-management Internet Services http://proteger.at [gesprochen: Prot-e-schee] Tel: 0660 / 415 65 31 ****** Radiointerview zum Thema Spam ****** http://www.it-podcast.at/archiv.html#podcast-100716 // Wir haben im Moment zwei Häuser zu verkaufen: // http://zmi.at/langegg/ // http://zmi.at/haus2009/
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