On 23/08/2011 03:23, Peter Jeremy wrote:
On 2011-Aug-22 12:45:08 +0200, Ivan Voras<ivo...@freebsd.org> wrote:
It would be suboptimal but only for the slight waste of space that would
have otherwise been reclaimed if the block or fragment size remained 512
or 2K. This waste of space is insignificant for the vast majority of
users and there are no performance penalties, so it seems that switching
to 4K sectors by default for all file systems would actually be a good idea.
This is heavily dependent on the size distribution. I can't quickly
check for ZFS but I've done some quick checks on UFS. The following
are sizes in MB for my copies of the listed trees with different UFS
frag size. These include directories but not indirect blocks:
1b 512b 1024b 2048b 4096b
4430 4511 4631 4875 5457 /usr/ncvs
4910 5027 5181 5499 6133 Old FreeBSD SVN repo
299 370 485 733 1252 /usr/ports cheched out from CVS
467 485 509 557 656 /usr/src 8-stable checkout from CVS
Note that the ports tree grew by 50% going from 1K to 2K frags and
will grow by another 70% going to 4KB frags. Similar issues will
be seen when you have lots of small file.
I agree but there are at least two things going for making the increase
anyway:
1) 2 TB drives cost $80
2) Where the space is really important, the person in charge usually
knows it and can choose a non-default size like 512b fragments.
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