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Re: cpio to ext4 seems much slower than to ext2, ext3 or xfs



On 11/12/2009 01:30 PM, Dennis J. wrote:
On 11/12/2009 05:59 PM, Eric Sandeen wrote:
Dennis J. wrote:
On 11/12/2009 04:03 PM, Eric Sandeen wrote:
Richard W.M. Jones wrote:

...

I'd like to repeat my proviso: I think this test is meaningless for
most users.

Until users have 8TB raids at home, which is not really that far off
...

Let's hope btrfs is production ready before then because extX doesn't
look like a fitting filesystem for such big drives due their lack of
online fsck.

ext4's fsck is much faster than ext3's, and xfs's repair tool is also
pretty speedy.

Both are offline, but so far online fsck for btrfs is just a goal, no
(released, anyway) code yet AFAIK.

Isn't the speed improvement of ext4 achieved by not dealing with empty
extends/blocks? If so that wouldn't help you much if those 8TB are
really used. But even a speedy fsck is going to take longer and longer
as filesystem size grows which is why I believe we will soon reach a
point were offline-fsck simply isn't a viable option anymore.
I have a 30TB storage system that I chopped into ten individual volumes
because current filesystems don't really make creating a single 30TB fs
a wise choice even though I'd like to be able to do that.

Regards,
Dennis


In our testing with f12, I build a 60TB ext4 file system with 1 billion small files. A forced fsck of ext4 finished in 2.5 hours give or take a bit :-) The fill was artificial and the file system was not aged, so real world results will probably be slower.

fsck time scales mostly with the number of allocated files in my experience. Allocated blocks (fewer very large files) are quite quick.

ric


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