[mythtv-users] my experience with myth on a solid state drive

Mark Lord mythtv at rtr.ca
Thu Jan 5 22:52:25 UTC 2012

On 12-01-05 02:32 PM, Ronald Frazier wrote:
> On Thu, Jan 5, 2012 at 2:25 PM, Tom Hayward <esarfl at gmail.com> wrote:
>> The special configuration I used can be summed up with my fstab:
>> /dev/sda    /               ext4    discard,noatime,errors=remount-ro 0       1
>> tmpfs    /tmp      tmpfs nodev,nosuid,size=5G          0 0
>> "discard" enables TRIM in ext4, if you SSD supports it. I'm not
>> concerned about wear, but I've never used atime, so decided it
>> wouldn't hurt to disable.
> Yeah, you need ext4 to get TRIM support, but I believe I read that it
> is very important to ONLY add "discard" if your drive supports it. I
> think I read that bad things could happen otherwise (no idea what sort
> of bad things). Being that my drive is a 1st gen Intel and they never
> ended up adding TRIM with a firmware update like they said they would,
> it was easy for me...just leave it out.

Specifying "discard" will slow things down.
Even on SSDs with Marvell controllers (eg. Intel, Crucial M4, etc..)
which do trim "properly", trim is simply added overhead.

And on most SSDs (eg. anything with Indilinx or Sandforce controllers)
trim commands are very slow to execute, and add unnecessary erase/rewrite
cycles, shortening the SSDs (albiet huge) lifespan.

Generally, trim is a total loss unless your SSD is mostly full (bad idea)
and writes consist of zillions of tiny unrelated blocks.


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