gjournal and TRIM: A safe combination?
rwmaillists at googlemail.com
Thu Oct 22 14:11:19 UTC 2015
On Tue, 20 Oct 2015 19:33:13 -0500
Brandon J. Wandersee wrote:
> I've recently created several new UFS partitions on an SSD. I
> activated gjournal on the largest--about 200Gb in size
> 1. UFS with TRIM, but without journaling. Disk performance is
> maintained, but data is unprotected in the event of a crash.
UFS with soft-updates is roughly equivalent to the the metadata
journalling used on most modern filesystems.
Personally, I wouldn't use gjournal on an SSD for several reasons:
1. full data journalling doubles the writes with respect to basic UFS
and therefore halves the life of the device. SU by contrast presumably
reduces the total writes by rolling-up multiple metadata updates in
2. the journal needs to be much larger than on an ordinary hard drive
because of the write speeds, which is wasteful.
3. I suspect gjournal has had very little use on SSDs, so there may be
SSD specific bugs.
I use gjournal with large partitions on spinning disks, and soft-updates
with foreground checks for my SSD and small partitions. I've never had
a problem with SUs with foreground checks.
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