Re: [gentoo-user] more tripleE SSD fs controversy

[Walter Dnes]

On Fri, Jun 05, 2009 at 02:41:33PM -0600, Maxim Wexler wrote

> hohndel doesn't specify any options, just says, use ext2. What does
> the group recommend?

  This is in the context of "cheap SSD" diask drives.  They behave
differently from hard disks, so "everything you know is wrong" if you
try stuff that applies to harddrives.  You want to minimize the number
of writes to disk as much as possible, for 2 reasons...

1) Cheap SSD disk drives are atrociously slow.  The fewer unnecessary
writes, the more responsive the machine will be.

2) Cheap SSD disk drives are liable to wear out after a lot of writes.
Fewer writes means a longer lifetime for the drive.

  This brings us to the question of exactly how to minimize writes.  I
suggest ext2fs with the "async" and "nodiratime" and "noatime" options.

* journalling file systems pound away continuously at the journal file.
  As Martha Stewart would say... "that is not a good thing" for cheap
  SSD drives

* async is the default, but it doesn't hurt to list it.  It says not to
  do a separate write for each request, but to do writes in bigger, and
  less frequent, batches.  The "mount (8)" manpage has this to say about
  sync...
> In case of media with limited number of write cycles (e.g. some flash
> drives) "sync" may cause life-cycle shortening.

* nodiratime says not to update directory inodes when accessed.  You do
  need to specify it, because it is not the default

* noatime says not to update file inodes when accessed.  You do need to
  specify it, because it is not the default.  I don't know if "noatime"
  implies "nodiratime", but I'd play it safe and specify both.

-- 
Walter Dnes <waltdnes@××××××××.org>