Mailinglist Archive: opensuse (686 mails)

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Re: [opensuse] SSD and smartctl: Percentage Used Endurance Indicator: 34 ?
  • From: Greg Freemyer <greg.freemyer@xxxxxxxxx>
  • Date: Sat, 6 Jul 2013 22:23:19 -0400
  • Message-id: <CAGpXXZ+50zqL=V2oDzvDmVjHvEh8ekbBA8Nav3piwtj62=uZDw@mail.gmail.com>
On Sat, Jul 6, 2013 at 10:00 PM, Rajko <rmatov101@xxxxxxxxxxx> wrote:
What you can do is to check your partition mount options. Other already
elaborated on that, but there is one that is probably missing -
"discard".

Check as root does your disk support TRIM:

hdparm -I /dev/sdX | grep -i TRIM

(X is a drive letter)

and if yes enable it with option "discard".

http://en.opensuse.org/SDB:SSD_discard_%28trim%29_support#Kernel_support

Article is a bit old, but even 12.3 does not enable discard by default.
Just checked 'mount' and neither root of the file system, not /home have
enabled option "discard".

Kernel "discard" support for ext4 was written years ago and the devs
did not know how SSDs would perform. The kernel discard feature for
ext4 in particular intersperses trim calls with data calls. From
performance testing, it appears a trim call forces a cache flush in
the SSD, so the end result is you get performance similar to running
with mount sync (ie. poor). Thus, in general this turned out to be a
bad design and is not how Windows 7 does it.

In general, the better solution is to send a batch of trim commands
during low utilization times. That is what win7 does. For ext4
fstrim will do that for you, so what a user should do is use cron to
schedule fstrim calls during periods of low usage for their PC.

Greg
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