Re: Samsung 840 EVO

["Sven Köhler" <sven.koehler@gmail.com>]

Am 04.05.2015 um 15:38 schrieb Günter Waller:
> But there is also a big concern for Linux users which this FW version
> seems to introduce. The link below points to a warning (backed by
> others, elsewhere on the web) that fstrim in combination with this FW
> will wreck your drive.
> http://www.overclock.net/t/1507897/samsung-840-evo-read-speed-drops-on-old-written-data-in-the-drive/2640%23post_23827674
> (search for fstrim)
> I raised this in a discussion thread of the Ubuntu MATE community and
> was pointed to the SSD blacklist that is part of the module
> libata-core.c which names you as the maintainer. I wonder if you could
> take a look at this issue - maybe you want to add the device to the
> blacklist thereafter if need be.
> If you find the time and find this worthwhile to investigate I would
> appreciate a brief notification of the outcome. For now I am holding
> back the FW update.

Here is a discussion of the issue and a patch:
https://bugs.launchpad.net/ubuntu/+source/fstrim/+bug/1449005

Apparently, TRIM in combination with NCQ is broken with the new
firmware. Having the discard mount option enabled didn't wreck my drive,
but it kept my machine from booting. I had to disable that option and
the patch given at the URL above seems to disable NCQ specifically for
TRIM only. So the performance hit might be minimal.

The patch should really be applied asap and it should be backported to
all stable branched as far as possible.


Regards,
  Sven