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    SubjectRe: Debugging system freezes on filesystem writes
    On 24.02.2013 03:20, Theodore Ts'o wrote:
    > On Sun, Feb 24, 2013 at 11:12:22AM +1100, Dave Chinner wrote:
    >>>> /dev/sda6 /home ext4 rw,noatime,discard 0 0
    >> ^^^^^^^
    >> I'd say that's your problem....
    > Looks like the Sandisk U100 is a good SSD for me to put on my personal
    > "avoid" list:
    > There are a number of SSD's which do not implement "trim" efficiently,
    > so these days, the recommended way to use trim is to run the "fstrim"
    > command out of crontab.

    OK. Removing 'discard' made it much better (the 60-600 second freezes
    are now 1-50 second freezes), but it's still at least an order of
    magnitude worse than a normal HD. When writing, that is -- reading is
    very fast (when there's no writing going on).

    So, after reading up a bit on this trimming I'm thinking maybe my
    filesystem's block sizes don't match up with my SSD's blocks (or
    whatever its write unit is called). Then writing a FS block would always
    write to multiple SSD blocks, causing multiple read-erase-write
    sequences, right? So how can I check this, and how can I make the FS
    blocks match the SSD blocks?

    Best regards,

     \ /
      Last update: 2013-02-26 20:23    [W:0.023 / U:55.916 seconds]
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