[pve-devel] [PATCH 06/20] lvm : add volume_protect && volume_unprotect
Alexandre DERUMIER
aderumier at odiso.com
Tue Dec 4 11:57:29 CET 2012
Hi Dietmar,
I have done some tests, with use lvm snapshots as clone image
parentvm : /dev/volume1/vm-122-disk-1
clone1: /dev/volume1/vm-888-disk-1 (#lvcreate -L 32G -s -n vm-888-disk-1 /dev/volume1/vm-122-disk-1)
clone2: /dev/volume1/vm-999-disk-1 (#lvcreate -L 32G -s -n vm-999-disk-1 /dev/volume1/vm-122-disk-1)
set parent to readonly:
#lvchange -pr /dev/volume1/vm-122-disk-1
activate vm-888-disk1 on node1
node1 #lvchange -aly /dev/volume1/vm-888-disk-1
Change of snapshot vm-888-disk-1 will also change its origin vm-122-disk-1 and 1 other snapshot(s). Proceed? [y/n]:
this activate all snapshots (vm-888-disk1 && vm-999-disk-1) on node1
node1#lvdisplay
--- Logical volume ---
LV Path /dev/volume1/vm-122-disk-1
LV Name vm-122-disk-1
VG Name volume1
LV UUID O5sfvK-JFYY-ouSw-Crj5-P3Zf-rRFP-aukTBD
LV Write Access read only
LV Creation host, time kvmtest1, 2012-12-04 10:42:45 +0100
LV snapshot status source of
vm-888-disk-1 [active]
vm-999-disk-1 [active]
LV Status available
# open 0
LV Size 32.00 GiB
Current LE 8192
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 254:57
--- Logical volume ---
LV Path /dev/volume1/vm-888-disk-1
LV Name vm-888-disk-1
VG Name volume1
LV UUID w42rX3-4D2G-Dy8c-l6Iz-xTVm-3TwY-J0GoPf
LV Write Access read/write
LV Creation host, time kvmtest2, 2012-12-04 11:16:03 +0100
LV snapshot status active destination for vm-122-disk-1
LV Status available
# open 0
LV Size 32.00 GiB
Current LE 8192
COW-table size 32.00 GiB
COW-table LE 8192
Allocated to snapshot 0.00%
Snapshot chunk size 4.00 KiB
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 254:59
--- Logical volume ---
LV Path /dev/volume1/vm-122-disk-1
LV Name vm-122-disk-1
VG Name volume1
LV UUID O5sfvK-JFYY-ouSw-Crj5-P3Zf-rRFP-aukTBD
LV Write Access read only
LV Creation host, time kvmtest1, 2012-12-04 10:42:45 +0100
LV snapshot status source of
vm-888-disk-1 [active]
vm-999-disk-1 [active]
LV Status available
# open 0
LV Size 32.00 GiB
Current LE 8192
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 254:57
--- Logical volume ---
LV Path /dev/volume1/vm-888-disk-1
LV Name vm-888-disk-1
VG Name volume1
LV UUID w42rX3-4D2G-Dy8c-l6Iz-xTVm-3TwY-J0GoPf
LV Write Access read/write
LV Creation host, time kvmtest2, 2012-12-04 11:16:03 +0100
LV snapshot status active destination for vm-122-disk-1
LV Status available
# open 0
LV Size 32.00 GiB
Current LE 8192
COW-table size 32.00 GiB
COW-table LE 8192
Allocated to snapshot 0.00%
Snapshot chunk size 4.00 KiB
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 254:59
activate vm-999-disk1 on node2
node2 #lvchange -aly /dev/volume1/vm-999-disk-1
Change of snapshot vm-888-disk-1 will also change its origin vm-122-disk-1 and 1 other snapshot(s). Proceed? [y/n]:
this activate all snapshots (vm-888-disk1 && vm-999-disk-1) on node2
node2#lvdisplay
--- Logical volume ---
LV Path /dev/volume1/vm-122-disk-1
LV Name vm-122-disk-1
VG Name volume1
LV UUID O5sfvK-JFYY-ouSw-Crj5-P3Zf-rRFP-aukTBD
LV Write Access read only
LV Creation host, time kvmtest1, 2012-12-04 10:42:45 +0100
LV snapshot status source of
vm-888-disk-1 [active]
vm-999-disk-1 [active]
LV Status available
# open 0
LV Size 32.00 GiB
Current LE 8192
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 254:57
--- Logical volume ---
LV Path /dev/volume1/vm-888-disk-1
LV Name vm-888-disk-1
VG Name volume1
LV UUID w42rX3-4D2G-Dy8c-l6Iz-xTVm-3TwY-J0GoPf
LV Write Access read/write
LV Creation host, time kvmtest2, 2012-12-04 11:16:03 +0100
LV snapshot status active destination for vm-122-disk-1
LV Status available
# open 0
LV Size 32.00 GiB
Current LE 8192
COW-table size 32.00 GiB
COW-table LE 8192
Allocated to snapshot 0.00%
Snapshot chunk size 4.00 KiB
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 254:59
--- Logical volume ---
LV Path /dev/volume1/vm-122-disk-1
LV Name vm-122-disk-1
VG Name volume1
LV UUID O5sfvK-JFYY-ouSw-Crj5-P3Zf-rRFP-aukTBD
LV Write Access read only
LV Creation host, time kvmtest1, 2012-12-04 10:42:45 +0100
LV snapshot status source of
vm-888-disk-1 [active]
vm-999-disk-1 [active]
LV Status available
# open 0
LV Size 32.00 GiB
Current LE 8192
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 254:57
--- Logical volume ---
LV Path /dev/volume1/vm-888-disk-1
LV Name vm-888-disk-1
VG Name volume1
LV UUID w42rX3-4D2G-Dy8c-l6Iz-xTVm-3TwY-J0GoPf
LV Write Access read/write
LV Creation host, time kvmtest2, 2012-12-04 11:16:03 +0100
LV snapshot status active destination for vm-122-disk-1
LV Status available
# open 0
LV Size 32.00 GiB
Current LE 8192
COW-table size 32.00 GiB
COW-table LE 8192
Allocated to snapshot 0.00%
Snapshot chunk size 4.00 KiB
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 254:59
Then I start vm 888 on node1 && vm 999 on node2.
Both booting fine, I can read/write inside them.
What is exactly the problem with snapshots in cluster if snapshots volume are active on each node ?
----- Mail original -----
De: "Dietmar Maurer" <dietmar at proxmox.com>
À: "Alexandre DERUMIER" <aderumier at odiso.com>
Cc: pve-devel at pve.proxmox.com
Envoyé: Mardi 4 Décembre 2012 06:04:31
Objet: RE: [pve-devel] [PATCH 06/20] lvm : add volume_protect && volume_unprotect
> I check on citrix xenserver, it seem to be possible to do linked clone from a
> lvm template.
>
> I don't know how it's works. maybe the clone is simply a snapshot ? does it
> work across cluster? (If the parent lvm volume is readonly and activate on
> each host ?)
No, lvm snapshot have problems on clusters.
I guess they simply use something like qcow2 with base image.
The base image of the qcow2 file points to the lvm device.
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