Re: Strange fragmentation in nearly empty filesystem

[Carsten Oberscheid <oberscheid@doctronic.de>]

On Tue, Jan 27, 2009 at 07:30:32AM -0600, Eric Sandeen wrote:
> It'd be best to run vmware under some other kernel, and observe its
> behavior, not just mount some existing filesystem and look at existing
> files and do other non-vmware-related tests.

If this really is just a vmware and/or kernel problem that has nothing
to do with the filesystem, then I agree.

> You went from a file with 34 holes to one with 27k holes by copying it?

Yep.

>  Perhaps this is cp's sparse file detection in action, seeking over
> swaths of zeros.
...
> Perhaps, if by "worse" you mean "leaves holes for regions with zeros".
> Try cp --sparse=never and see how that goes.

Didn't know this one.


[co@tangchai]~/vmware/foo cp --sparse=never foo.vmem test_nosparse

[co@tangchai]~/vmware/foo xfs_bmap -vvp test_ | grep hole | wc -l
test_livecd    test_nosparse  

[co@tangchai]~/vmware/foo xfs_bmap -vvp test_nosparse | grep hole | wc -l
0

[co@tangchai]~/vmware/foo xfs_bmap -vvp test_nosparse | grep -v hole | wc -l
9


You win.

> My best guess is that your cp test is making the file even more sparse
> by detecting blocks full of zeros and seeking over them, leaving more
> holes.  Not really related to vmware behavior, though.

All right. So next I'll try and downgrade vmplayer.

Just out of couriosity (and stubbornness): Are there any XFS
parameters that might influence fragmentation for the better, in case
I have to put up with a stupid application?

Thanks for your time & thoughts & best regards


Carsten Oberscheid

-- 
carsten oberscheid                  d  o  c  t  r  o  n  i  c
email oberscheid@doctronic.de       information publishing + retrieval
phone +49 228 92 682 00             http://www.doctronic.de

doctronic GmbH & Co. KG, Bonn
Handelsregister: HRA 4685 (AG Bonn); USt-ID: DE 210 898 186
Komplementärin:  doctronic Verwaltungsges. mbH, Bonn, HRB 8926 (AG Bonn)
Geschäftsführer: Holger Flörke, Ingo Küper, Carsten Oberscheid

_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs