Thomas,
Enabling compression and filling the inner file-system with null fixed
the problem.
I think I might leave compression on. I still need to do more testing on
that.
Thanks!
On 08/05/10 03:15, Tomas Ögren wrote:
On 04 August, 2010 - Karl Rossing sent me these 5,4K bytes:
Hi,
We have a server running b134. The server runs xen and uses a vdev as
the storage.
The xen image is running nevada 134.
I took a snapshot last night to move the xen image to another server.
NAME USED AVAIL REFER MOUNTPOINT
vpool/host/snv_130 32.8G 11.3G 37.7G -
vpool/host/snv_...@2010-03-31 3.27G - 13.8G -
vpool/host/snv_...@2010-08-03 436M - 37.7G -
It's also worth noting that vpool/host/snv_130 is a clone at least two
other snapshots.
I then did a zfs send of vpool/host/snv_...@2010-08-03 and got a 39GB file.
A zfs send of vpool/host/snv_...@2010-03-31 gave a file of 15GB.
This is probably data + metadata or similar.
I don't understand why the file is 39GB since df -h inside of the xen
image drive vpool/host/snv_130 shows:
Filesystem size used avail capacity Mounted on
rpool/ROOT/snv_130 39G 12G 22G 35% /
It would be nice if the zfs send file would be roughly the same size as
the space used inside of xen machine.
The filesystem on the inside might have touched all the blocks, but not
informed the outer ZFS (because it can't) that some blocks are freed.
One way of making it smaller is to enable compression on the outer
zvol, disable compression on the inner filesystem and then fill the
inner filesystem with null (dd if=/dev/zero of=file bs=1024k) and remove
that file, then remove compression (if you want). This is just a
temporary thing, as the filesystem will be used on the inside (with Copy
on Write), the outer one will grow back again.
/Tomas
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