Mailinglist Archive: opensuse (1786 mails)

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Re: [opensuse] Re: SSD in openSUSE.
  • From: Roger Luedecke <roger.luedecke@xxxxxxxxx>
  • Date: Tue, 22 Nov 2011 17:54:30 -0800
  • Message-id: <3615846.xerQRfb5rt@frankensuse>
On Tuesday, November 22, 2011 08:42:10 PM Greg Freemyer wrote:
On Tue, Nov 22, 2011 at 7:44 PM, Joachim Schrod <jschrod@xxxxxxx> wrote:
If you can afford it, don't use 15% of the disk. To get this free
space, use secure erase to reset the disk's firmware notion of what
you're using, and then don't allocate 15% of the disk during
partitioning.

Undocumented feature time. First secure erase is not always
implemented on SSDs, so don't trust it.

Second, modern versions of the mkfs tools take care of discard/trim
for you. ie. They discard/trim all the unallocated parts of the drive
during the format process.

In fact if you don't want that to happen, you have to specify it via:

mkfs.ext4 -E nodiscard /dev/sdxx

I don't know when that was introduced, but os 12.1 has it in the
binary, but not in the man page. I strongly suspect 11.4 is similar.
No idea about 11.3.

Anyway, XFS uses -K for the same thing. (And its in the man page!)

mkfs.xfs -K /dev/sdxx

So if you really want to keep back 15%, I would create a fullsize
partition, format with mkfs, then delete the partition and create one
15% smaller, then format again with mkfs.

Greg
What would be a good filesystem catering to SSD strenghts and weaknesses? A
friend of mine swears by XFS.
--
Roger Luedecke
openSUSE Ambassador
Ind. Repairs and Consulting
**Looking for a C++ etc. mentor***
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