[zfs-discuss] Re: TRIM support?

Manuel Amador rudd-o at rudd-o.com
Thu Mar 1 11:10:31 EST 2012

That sounds good.  You should file a bug request specifically for that 
feature, and another for issuing discards to underlying block devices that 
store data.
On Thursday, March 01, 2012 16:51:42 Gregor Kopka wrote:
> Am 01.03.2012 09:03, schrieb Stephane Chazelas:
> > 2012-02-29 23:08:08 -0800, Christ Schlacta:
> >> Is it possible to add TRIM support to the zvol layer?  I know
> >> because of COW that it may not always be useful, but it would be
> >> nice to be able to mark blocks of data as "no longer referenced", so
> >> that when appropriate (IE: when deleting snapshots) the space that
> >> would otherwise be unused but referenced can instead be freed.
> >> There exists a spec for it, it'd be nice to be able to use it :)
> > 
> > It's been added recently and is available in the latest ppa. And
> > I did verify that it works (BLKDISCARD ioctl works, so I expect
> > mounting a FS with -o discard on a zvol should work as well).
> Does it work for CACHE and LOG devices based on SSD, since they need
> this to stay alive and snappy for a reasonable amount of time.
> On pool import a TRIM over the whole CACHE block device would make sense
> too, since L2ARC contents do not persist over a reboot anyway...
> Gregor

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