Mailinglist Archive: opensuse-factory (439 mails)

< Previous Next >
Re: [opensuse-factory] Adding SSDs?
  • From: C <smaug42@xxxxxxxxxxxx>
  • Date: Thu, 13 Mar 2014 13:21:02 +0100
  • Message-id: <>
On Thu, Mar 13, 2014 at 1:10 PM, Greg Freemyer wrote:
C <smaug42@xxxxxxxxxxxx> wrote:

On Thu, Mar 13, 2014 at 9:26 PM, Jason <relentropy@xxxxxxxxx> wrote:
As for the discard, few people have told me in the past few days not
to use it
and considering they know what they're talking about I'm not
questioning it so
I have personally removed it.

The only reason I can think of that someone would suggest not using
discard is that it can impact the speed of deleting content off the

That blog post is directly on point for why I recommended fstrim over discard.

As I put in an earlier email, until recently all SSDs implemented trim as a
non-queue-able command, so every trim command triggered a internal drive
cache flush. Per that blog post that caused a 40x increase in time to delete
an unpacked kernel tree. Ie. It makes ext4 perform like xfs of 3 years ago.

Newer SSDs may have finally implemented trim as a queue-able command and thus
the cache flush is no longer done. For them discard should be a fine option,
but I've seen no benchmarks.

Unfortunately I don't know how to know which way a SSD has the trim command
implemented. Maybe do what the blog author did and test untar'ing and
deleting a kernel tarball. Be sure to include the time for sync after rm -r.

I'm willing to time test the discard thing on my system (on the
Samsung 840 Pro)... but it will have to wait for at least 3 weeks
(travelling starting pretty much.. now). I haven't noticed any speed
impact, but then again, I don't usually untar and then delete the
kernel source (or do similar large tasks).

openSUSE 13.1 x86_64, KDE 4.12
To unsubscribe, e-mail: opensuse-factory+unsubscribe@xxxxxxxxxxxx
To contact the owner, e-mail: opensuse-factory+owner@xxxxxxxxxxxx

< Previous Next >