Hi,
Just noticed something about df -h output I didn''t expect.
I''m sorry if this has already been answered or is a know problem.
Just see the test-part below to see what I did.
____ setup ____
- installed Fedora 16 Alpha on a KVM-VM with one 8GB HD-image.
- did a yum update
( - got a kernel update, which broke grub setup, worked around it:
kernel I use is: 3.0.0-1.fc16.x86_64)
- installed btrfs-progs
- created a directory /test
- created 2 files with dd from /dev/zero with the size of 2GB in /test
- created 2 loopback devices of the files
- created a btrfs filesystem with RAID 1 data and RAID1 meta-data
- created directory /test/mnt
____ test _____
- mounted the btrfs filesystem on /test/mnt
- created a file of 256MB with dd from /dev/zero in /test/mnt
- created a snapshot of /test/mnt in /test/mnt/snap1
- deleted 256MB file in /test/mnt
- deleted snapshot /test/mnt/snap1
- checked df -h, 256MB wasn''t released. The filesystem does not look
empty
- unmounted /test/mnt
- mounted /test/mnt
- checked df -h, 256MB was released. The filesystem does look empty
Hope this is helpful.
Have a nice day,
Leen.
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On Mon, Sep 05, 2011 at 11:50:43AM +0200, Leen Besselink wrote:> Hi, > > Just noticed something about df -h output I didn''t expect. > > I''m sorry if this has already been answered or is a know problem. > > Just see the test-part below to see what I did. > > ____ setup ____ > > - installed Fedora 16 Alpha on a KVM-VM with one 8GB HD-image. > - did a yum update > ( - got a kernel update, which broke grub setup, worked around it: > kernel I use is: 3.0.0-1.fc16.x86_64) > - installed btrfs-progs > - created a directory /test > - created 2 files with dd from /dev/zero with the size of 2GB in /test > - created 2 loopback devices of the files > - created a btrfs filesystem with RAID 1 data and RAID1 meta-data > - created directory /test/mnt > > ____ test _____ > > - mounted the btrfs filesystem on /test/mnt > - created a file of 256MB with dd from /dev/zero in /test/mnt > - created a snapshot of /test/mnt in /test/mnt/snap1 > - deleted 256MB file in /test/mnt > - deleted snapshot /test/mnt/snap1 > - checked df -h, 256MB wasn''t released. The filesystem does not look empty > - unmounted /test/mnt > - mounted /test/mnt > - checked df -h, 256MB was released. The filesystem does look empty > > Hope this is helpful.Snapshot/subvolume deletion is asynchronous -- it can take a while to happen. Try waiting a minute or two after the snapshot deletion and before looking at df -h. Hugo. -- === Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk == PGP key: 515C238D from wwwkeys.eu.pgp.net or http://www.carfax.org.uk --- If it''s December 1941 in Casablanca, what time is it --- in New York?
On 09/05/2011 12:19 PM, Hugo Mills wrote:> > Snapshot/subvolume deletion is asynchronous -- it can take a while > to happen. Try waiting a minute or two after the snapshot deletion and > before looking at df -h. > > Hugo. >As I didn''t see any disc activity, I thought it was done. I just tried it again, it does seem to work the way you mentioned. Thanks. Just a quick question: would ''btrfs filesystem sync /path'' help speed that up ? Like for example if a sys-admin sees that he''s running out of space and needs to remove some old snapshots immediately. Or when an automated backup first removes old snapshots to create room for a new backup just before starting that backup. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html