Hi all,
I'm trying to convert images (mostly qcow2) to raw format on thin lv,
hoping to write only the allocated blocks on the thin lv, but
it seems that qemu-img cannot write sparse image on a block
device.
Here is an example:
Create a new thin lv:
# lvcreate --name raw-test --virtualsize 20g --thinpool pool0 ovirt-local
Using default stripesize 64.00 KiB.
Logical volume "raw-test" created.
[root@voodoo6 ~]# lvs ovirt-local
LV VG Attr LSize
Pool Origin Data% Meta% Move Log Cpy%Sync Convert
029060ab-41ef-4dfd-9a3e-4c716c01db06 ovirt-local Vwi-a-tz-- 20.00g
pool0 6.74
4f207ee8-bb47-465a-9b68-cb778e070861 ovirt-local Vwi-a-tz-- 20.00g
pool0 0.00
7aed605e-c74c-40d8-b449-8a1bf7228b8b ovirt-local Vwi-a-tz-- 20.00g
pool0 6.98
ce6d08d3-350f-4afa-a0e7-7b492a1a7744 ovirt-local Vwi-a-tz-- 20.00g
pool0 6.87
pool0 ovirt-local twi-aotz-- 40.00g
10.30 5.49
raw-test ovirt-local Vwi-a-tz-- 20.00g
pool0 0.00
I want to convert this image (fresh fedora 25 installation):
# qemu-img info fedora.qcow2
image: fedora.qcow2
file format: qcow2
virtual size: 20G (21474836480 bytes)
disk size: 1.3G
cluster_size: 65536
Format specific information:
compat: 1.1
lazy refcounts: false
refcount bits: 16
corrupt: false
Convert the image to raw, into the new thin lv:
# qemu-img convert -p -f qcow2 -O raw -t none -T none fedora.qcow2
/dev/ovirt-local/raw-test
(100.00/100%)
The image size was 1.3G, but now the thin lv is fully allocated:
# lvs ovirt-local
LV VG Attr LSize
Pool Origin Data% Meta% Move Log Cpy%Sync Convert
029060ab-41ef-4dfd-9a3e-4c716c01db06 ovirt-local Vwi-a-tz-- 20.00g
pool0 6.74
4f207ee8-bb47-465a-9b68-cb778e070861 ovirt-local Vwi-a-tz-- 20.00g
pool0 0.00
7aed605e-c74c-40d8-b449-8a1bf7228b8b ovirt-local Vwi-a-tz-- 20.00g
pool0 6.98
ce6d08d3-350f-4afa-a0e7-7b492a1a7744 ovirt-local Vwi-a-tz-- 20.00g
pool0 6.87
pool0 ovirt-local twi-aotz-- 40.00g
60.30 29.72
raw-test ovirt-local Vwi-a-tz-- 20.00g
pool0 100.00
Recreate the lv:
# lvremove -f ovirt-local/raw-test
Logical volume "raw-test" successfully removed
# lvcreate --name raw-test --virtualsize 20g --thinpool pool0 ovirt-local
Using default stripesize 64.00 KiB.
Logical volume "raw-test" created.
Covert the qcow image to raw sparse file:
# qemu-img convert -p -f qcow2 -O raw -t none -T none fedora.qcow2 fedora.raw
(100.00/100%)
# qemu-img info fedora.raw
image: fedora.raw
file format: raw
virtual size: 20G (21474836480 bytes)
disk size: 1.3G
Write the sparse file to the thin lv:
# dd if=fedora.raw of=/dev/ovirt-local/raw-test bs=8M conv=sparse
2560+0 records in
2560+0 records out
21474836480 bytes (21 GB) copied, 39.0065 s, 551 MB/s
Now we are using only 7.19% of the lv:
# lvs ovirt-local
LV VG Attr LSize
Pool Origin Data% Meta% Move Log Cpy%Sync Convert
029060ab-41ef-4dfd-9a3e-4c716c01db06 ovirt-local Vwi-a-tz-- 20.00g
pool0 6.74
4f207ee8-bb47-465a-9b68-cb778e070861 ovirt-local Vwi-a-tz-- 20.00g
pool0 0.00
7aed605e-c74c-40d8-b449-8a1bf7228b8b ovirt-local Vwi-a-tz-- 20.00g
pool0 6.98
ce6d08d3-350f-4afa-a0e7-7b492a1a7744 ovirt-local Vwi-a-tz-- 20.00g
pool0 6.87
pool0 ovirt-local twi-aotz-- 40.00g
13.89 7.17
raw-test ovirt-local Vwi-a-tz-- 20.00g
pool0 7.19
This works, but it would be nicer to have a way to convert
to raw sparse to a block device in one pass.
Nir
