On Mittwoch, 5. Januar 2011 Lukas Czerner wrote:
> If we
> notice that we are running out of space in advance (how much in
> advance?), we can start trimming smaller chunks, until we reach
> reasonable a reasonable pool of reclaimed space, or until we trim
> the whole device.
Would it be possible that all blocks that have been in use since the
last FITRIM run can be logged? Like this, we would only need to clean
those. If you have a 2TB volume, probably only 25% of it have been
rewritten (=500GB) since the last run, and of that maybe 80% are still
in use at the time we run FITRIM, so only 100GB would need the cleanup.
Maybe each AG could store a bitmap of written blocks, that are reset by
a FITRIM run. That could be an asynchronous written bitmap and shouldn't
disturb performance too much. Maybe it's even only needed to store a bit
per sunit*swidth blocks, to keep that table small. A mount option could
be used to enable that feature, so only those which use thin
provisioning or SSDs or similar devices enable it at wish.
Especially for 100TB size devices that seems like something that should
be thought of, as maybe if you run FITRIM once a week there, only <10TB
have been rewritten, if at all, and such a table would boost a FITRIM
run a lot.
But maybe this is just bullshit of my tired brain, and I'm not a dev so
I have no idea how hard it would be to implement that.
mit freundlichen Grüssen,
Michael Monnerie, Ing. BSc
it-management Internet Services: Protéger
http://proteger.at [gesprochen: Prot-e-schee]
Tel: +43 660 / 415 6531
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