> Op 27 juni 2017 om 13:56 schreef Christian Balzer <[email protected]>: > > > On Tue, 27 Jun 2017 13:24:45 +0200 (CEST) Wido den Hollander wrote: > > > > Op 27 juni 2017 om 13:05 schreef Christian Balzer <[email protected]>: > > > > > > > > > On Tue, 27 Jun 2017 11:24:54 +0200 (CEST) Wido den Hollander wrote: > > > > > > > Hi, > > > > > > > > I've been looking in the docs and the source code of BlueStore to > > > > figure out if it issues TRIM/Discard [0] on SSDs and I haven't been > > > > able to find an answer. > > > > > > > > Does BlueStore/BlueFS issue these commands to give back the space to > > > > the underlying device? > > > > > > > > For SSDs it improves both write performance and their lifespan, so it > > > > would be a very nice to have feature. > > > > > > > > SATA 3.1 has "Queued TRIM Command" which allows it to be 'async' in the > > > > controller. > > > > > > > If it were that last bit, I'd be for it, if it isn't then something that > > > you can fully control akin to fstrim would be a much better idea. > > > > > > > Problem is that you can't run fstrim on BlueStore since it's not a mounted > > filesystem like XFS. Therefor TRIM/Discard would have to be issued by the > > OSD. > > > > I wrote akin, so lets call it bluetrim. > Bluestore already needs too know what blocks are allocated and which not, > so in a typical case stop the osd (noout first), run "bluetrim", fire it > up again. > Maximum speed of trim, no complex logic and most likely least amount of > client performance impact.
Would be great to have that offline as well! The currently outstanding PR already allows for enable and disable of trim: https://github.com/ceph/ceph/pull/14727 Wido > > Christian > > > > That being said, I'm disinclined to deploy any SSDs that actually REQUIRE > > > trim/discard to maintain their functional levels. > > > > > > > I wouldn't say require, but it never hurts to actually do a TRIM/Discard > > when it comes to the lifespan of a SSD. > > > > However, I'm curious if this is actually in BlueStore or not. > > > > Wido > > > > > Christian > > > -- > > > Christian Balzer Network/Systems Engineer > > > [email protected] Rakuten Communications > > > > > -- > Christian Balzer Network/Systems Engineer > [email protected] Rakuten Communications _______________________________________________ ceph-users mailing list [email protected] http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
