[zfs-discuss] Re: TRIM support?

Manuel Amador rudd-o at rudd-o.com
Fri Mar 2 07:46:56 EST 2012


My SSD is large enough that I use it as a data vdev.  My laptop runs ZFS.

On Thursday, March 01, 2012 09:26:10 Christ Schlacta wrote:

I got exactly what I want. I dunno about the other guy. I like where he's 
going with it, but his request is obviously lower priority due to the fact 
that it won't be extremely useful until ssds are large enough to use as data 
vdevs 
On Mar 1, 2012 8:03 AM, "Richard Yao" <ryao at cs.stonybrook.edu> wrote:

The TRIM support permits zvols to shrink. It does not touch the devices.

On Thu, Mar 1, 2012 at 10:51 AM, Gregor Kopka <gregor at kopka.net> 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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