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Date:      Mon, 18 May 2015 10:18:41 -0400
From:      mfv <mfv@bway.net>
To:        Arthur Chance <freebsd@qeng-ho.org>
Cc:        Warren Block <wblock@wonkity.com>, freebsd-questions@freebsd.org
Subject:   Re: Setting Trim _AFTER_ a New Install
Message-ID:  <20150518101841.6fcd9a12@gecko4>
In-Reply-To: <55277D4D.4010802@qeng-ho.org>
References:  <20150409152321.65de5fd0@gecko4> <alpine.BSF.2.20.1504091521170.1276@wonkity.com> <55277D4D.4010802@qeng-ho.org>

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On Fri, 10 Apr 2015 08:35:41 +0100
Arthur Chance <freebsd@qeng-ho.org> wrote:

> On 09/04/2015 22:27, Warren Block wrote:
> > On Thu, 9 Apr 2015, mfv wrote:
> >
> >> Hello,
> >>
> >> I've recently installed FreeBSD r10.1 using bsdinstall and then
> >> loaded a large number of programs and data.  After spending
> >> considerable time on the installation I discovered that my SSD has
> >> TRIM which appears to be quite useful. After some investigation I
> >> understand that it is a simple flag that can be set after booting
> >> into single user mode.
> >>
> >> I hope my questions are  simple:
> >>
> >> If TRIM is enabled will it mess up the disk so that everything has
> >> to be reinstalled?
> >
> > No, it will not harm the data.  That said, before running tunefs to
> > enable it, make a backup.  Always make a backup.
> >
> >> If not, is there anything else I should be aware of?
> >
> > If you used ZFS-on-root, tunefs(8) and TRIM do not apply.  ZFS uses
> > TRIM natively now, but I'm not sure if that was in 10.1 or only now
> > in 10-STABLE.
> 
> I'm on 10.1-REL, it's got TRIM in zfs
> 
> root@arthur# sysctl vfs.zfs | grep trim
> vfs.zfs.vdev.trim_on_init: 1
> vfs.zfs.vdev.trim_min_active: 1
> vfs.zfs.vdev.trim_max_active: 64
> vfs.zfs.vdev.trim_max_bytes: 2147483648
> vfs.zfs.vdev.trim_max_pending: 64
> vfs.zfs.trim.enabled: 1
> vfs.zfs.trim.txg_delay: 32
> vfs.zfs.trim.timeout: 30
> vfs.zfs.trim.max_interval: 1
> 
> 

Just wanted to send a long overdue thanks for your help.

I followed Warren's admonition of doing a backup before changing the
flag and was glad I did.  Early in the morning, without being
sufficiently caffeinated, I typed newfs rather than tunefs. That, of
course, wiped out the disk.  During re-installation the TRIM flag was
set and the old data reloaded.  The SSD performance is wonderful.

Let this message be another object lesson of doing backups (and a plug
for the caffeine industry).

    Cheers ...                                 __o
                                             _ \<,_
    Marek                                   (+)/ (+)
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