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Date:      Tue, 20 Oct 2015 19:33:13 -0500
From:      Brandon J. Wandersee <brandon.wandersee@gmail.com>
To:        freebsd-questions@freebsd.org
Subject:   gjournal and TRIM: A safe combination?
Message-ID:  <867fmh12nq.fsf@WorkBox.Home>

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I've recently created several new UFS partitions on an SSD. I activated
gjournal on the largest--about 200Gb in size--and afterward received a
warning during boot-up:

    WARNING: /usr/home: TRIM flag on fs but disk does not confirm that
    it supports TRIM

The disk does indeed support TRIM, and `camcontrol identify` can detect
as much, but it seems gjrounal interferes with this detection. But does
it actually interfere with TRIM in any way? More importantly, does it
endanger the data on the filesystem at all? The real issue, I suppose,
is that there are four possible formatting options:

1. UFS with TRIM, but without journaling. Disk performance is
maintained, but data is unprotected in the event of a crash.

2. UFS with journaling, but without TRIM. Data is likely protected should a
crash occur, but the filesystems need to be periodically recreated with
`newfs -E`to restore performance.

4. UFS with both journaling and TRIM. Ideal, so long as one doesn't
interfere with the other.

3. UFS with neither journaling or TRIM. Not an option.

I guess I'm just curious which of the first three I should go for. Daily
backups are part of my routine in any case. Thanks in advance for any
advice or clarification.
-- 
==================================================================
   		      :: Brandon Wandersee ::
                  :: brandon.wandersee@gmail.com ::
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'A common mistake that people make when trying to design something
completely foolproof is to underestimate the ingenuity of complete
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