On Mon, May 30, 2016 at 04:48:36PM +0800, baotiao wrote:
> how can I set the extent size hint to a file with command line?
>
> I have google for a lot, but I can't find a answer
>
It can be set with xfs_io, like:
xfs_io -c "extsize 8m" <file> # To set an extent size hint of 8m
Although, it only works if the file is empty, or more specific, the file must
not have any extents allocated
> ----------------------------------------
>
> Github: [1]https://github.com/baotiao
> Blog: [2]http://baotiao.github.io
> Stackoverflow: [3]http://stackoverflow.com/users/634415/baotiao
> Linkedin: [4]http://www.linkedin.com/profile/view?id=145231990
>
> On May 30, 2016, at 13:04, Dave Chinner <[5]david@xxxxxxxxxxxxx> wrote:
>
> On Mon, May 30, 2016 at 12:45:07PM +0800, baotiao wrote:
>
> This machine is running for qemu, the file is qemu qcow file type
> [root@w-openstack20
> /data/nova/instances/7898b630-c4ef-49ab-9ce9-3735e090c282]# file
> disk
> disk: QEMU QCOW Image (v3), has backing file (path
> /data/nova/instances/_base/3f27393376152ac352b2d85703011e38517e),
> 429496729600 bytes
>
> Oh, you're using delta/snapshot based qcow images. That, by it's
> very nature, generates fragmented image files as they are a delta
> over the backing file.
> ....
>
> actual 48421430, ideal 20716, fragmentation factor 99.96%
> How can I solve this problem, what do you suggest me to do?
>
> Use a extent size hint (say 1-8MB) for your qcow2 image files so that
> they don't fragment badly as they are written to.
> Cheers,
> Dave.
> --
> Dave Chinner
> [6]david@xxxxxxxxxxxxx
>
> References
>
> 1. https://github.com/baotiao
> 2. http://baotiao.github.io/
> 3. http://stackoverflow.com/users/634415/baotiao
> 4. http://www.linkedin.com/profile/view?id=145231990
> 5. mailto:david@xxxxxxxxxxxxx
> 6. mailto:david@xxxxxxxxxxxxx
> _______________________________________________
> xfs mailing list
> xfs@xxxxxxxxxxx
> http://oss.sgi.com/mailman/listinfo/xfs
--
Carlos
|