Re: ext4 - 52.2% non-contiguous
On Fri, Jul 10, 2009 at 02:29:10PM +0900, Miles Bader wrote:
> Actually shouldn't ext4 do _better_ (than ext3 etc) in such a case,
> since it does allocate-on-write, allowing it to allocate contiguous
> storage despite the user writes being small?
Depends. If an application doesn't pre-allocate space on the filesystem
for each file, then extents aren't going to help much. I don't know if
rsync pre-allocates or not, but your experience indicates "not."
In order to pre-allocate, the file system would need to know the file
size to allocate before opening a file handle for write; this obviously
wouldn't work well if writing from a stream or a rolling merge like
rsync.
If you're hell-bent on using rsync, you might try the --whole-file
option, and see if that helps. I'd be curious to know the answer to that
myself.
--
"Oh, look: rocks!"
-- Doctor Who, "Destiny of the Daleks"
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