Mike Fedyk wrote:
On Wed, Mar 10, 2010 at 11:49 AM, Gordan Bobic <gordan@xxxxxxxxxx> wrote:
I'm looking to try BTRFS on a SSD, and I would like to know what SSD
optimizations it applies. Is there a comprehensive list of what ssd mount
option does? How are the blocks and metadata arranged? Are there options
available comparable to ext2/ext3 to help reduce wear and improve
performance?
Specifically, on ext2 (journal means more writes, so I don't use ext3 on
SSDs, since fsck typically only takes a few seconds when access time is <
100us), I usually apply the
-b 4096 -E stripe-width = (erase_block/4096)
parameters to mkfs in order to reduce the multiple erase cycles on the same
underlying block.
Are there similar optimizations available in BTRFS?
I think you'll get more out of btrfs, but another thing you can look
into is ext4 without the journal. Support was added for that recently
(thanks to google).
How is this different to using mkfs.ext2 from e4fsprogs?
And while I appreciate hopeful remarks along the lines of "I think
you'll get more out of btrfs", I am really after specifics of what the
ssd mount option does, and what features comparable to the optimizations
that can be done with ext2/3/4 (e.g. the mentioned stripe-width option)
are available to get the best possible alignment of data and metadata to
increase both performance and life expectancy of a SSD.
Also, for drives that don't support TRIM, is there a way to make the FS
apply aggressive re-use of erased space (in order to help the drive's
internal wear-leveling)?
I have looked through the documentation and the wiki, but it provides
very little of actual substance.
Gordan
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