[zfs-discuss] zfs and fstrim

fermulator fermulator at sympatico.ca
Wed Jan 20 20:36:35 EST 2016

Official information is here: http://open-zfs.org/wiki/Features#TRIM_Support

For an elaboration into Gordan's option 2) there are numerous articles 
online on how to do it; some examples, see

-------- Original Message --------
From: Gordan Bobic via zfs-discuss <zfs-discuss at list.zfsonlinux.org>
Sent: 1/20/2016, 9:41:18 AM
To: General discussion - ask questions, receive answers and advice from 
other ZFS users <zfs-discuss at list.zfsonlinux.org>
Subject: Re: [zfs-discuss] zfs and fstrim

> There are a few options:
> 1.1) You don't
> 1.2) Leave untouched partition/space on a freshly secure-erased SSD so 
> that the SSD has more known untouched blocks to work with 
> (under-provisioning), and you don't worry about TRIM-ing.
> 2) Drop the SSD out of the array (make sure your redundancy is up to 
> the task), ATA secure erase it, re-add it, resilver. Space that isn't 
> used will be freshly trimmed. Repeat for all SSDs in the pool.
> In most cases 1.1) is good enough as SSDs are internally adequately 
> overprovisioned to handle this reasonably well, especially ones based 
> on Sandforce controllers that internally compress and dedupe the data.
> On Wed, Jan 20, 2016 at 2:17 PM, John Covici via zfs-discuss 
> <zfs-discuss at list.zfsonlinux.org 
> <mailto:zfs-discuss at list.zfsonlinux.org>> wrote:
>     Hi.  Since zfs does not support fstrim, how should I trim my pool?  I
>     have a pool with a number of datasets as  legacy mountpoints on 2 ssd
>     drives -- so do I do each one separately, or how to do this properly?
>     Thanks in advance for any suggestions.
>     --
>     Your life is like a penny.  You're going to lose it. The question is:
>     How do
>     you spend it?
>              John Covici
>     covici at ccs.covici.com <mailto:covici at ccs.covici.com>
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