Thanks for your reply. I tested it out and it does not seem to work
(lvm2 version used is 2.02.98-6ubuntu2):
lvcreate -n testvolume3 -L 1G vg
lvcreate -n testvolume3_snapshot -s /dev/vg/testvolume3 -l100%ORIGIN
dd if=/dev/zero of=/dev/vg/testvolume3 bs=1G count=1
After this the snapshot is invalid:
testvolume3_snapshot vg swi-I-s-- 1.00g testvolume3 100.00
I checked out the lvm2 source code and found the methods cow_max_extents
and _cow_max_size in snapshot_manip.c. Do these methods calculate the
exact max size of the snapshot meta data?
On 01/14/2015 09:34 AM, Zdenek Kabelac wrote:
Dne 14.1.2015 v 08:24 Bram Klein Gunnewiek napsal(a):
Hello,
I am trying to create snapshots of thick volumes that can't break
because they
overflow (thin volumes are not an option right now). I can't find
information
on how to calculate (in advance) the metadata overhead of a snapshot
when all
blocks in the origin volume are changed (e.g. the snapshot is 100%
full). Is
there a way to do this?
Recent versions of lvm2 (let's say >= 111) are able to determine this
size automatically - just use: 'lvcreate -s -l100%ORIGIN vg/origin'
Regards
Zdenek
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