[Gluster-users] Sparse Files and Heal

Lindsay Mathieson lindsay.mathieson at gmail.com
Tue Nov 18 12:05:06 UTC 2014

I have a VM image which is a sparse file - 512GB allocated, but only 32GB used.

root at vnb:~# ls -lh /mnt/gluster-brick1/datastore/images/100
total 31G
-rw------- 2 root root 513G Nov 18 19:57 vm-100-disk-1.qcow2

I switched to full sync and rebooted.

heal was started on the image and it seemed to be just transfering the full file from node 
vnb to vng. iftop showed bandwidth at 500 Mb/s

Eventually the cumulative transfer got to 140GB which seemed odd as the real file size was 
31G. I logged onto the second node (vng) and the *real* file size  size was up to 191Gb.

It looks like the heal is not handling sparse files, rather it is transferring empty bytes to 
make up the allocated size. Thats a serious problem for the common habit of over 
committing your disk space with vm images. Not to mention the inefficiency.


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