[pve-devel] kvm disk template implementation ideas

Alexandre DERUMIER aderumier at odiso.com
Thu Aug 23 12:11:06 CEST 2012


- either explicit: by using different volume names 
- or implicit: we generate the real snapshot volume names as F(volid, snapshotname) 

I think we need implicit,
I don't see how explicit can work. 
Volume name is always the same, snapshot should just be a reference name of a point in time

qcow2
-----
#qemu-img create -f qcow2 image1 1G
# qemu-img snapshot -c snap1 image1
# qemu-img snapshot -l image1
Snapshot list:
ID        TAG                 VM SIZE                DATE       VM CLOCK
1         snap1                     0 2012-08-23 12:09:15   00:00:00.000


sheepdog
--------
#  collie vdi create image1 1G
# collie vdi snapshot -s snap1 image1
# collie vdi list
  Name        Id    Size    Used  Shared    Creation time   VDI id  Tag
s image1       1  1.0 GB  0.0 MB  0.0 MB 2012-08-23 11:55   737a91  snap1
  image1       2  1.0 GB  0.0 MB  0.0 MB 2012-08-23 11:56   737a92  


rbd
---
#rbd create --size 1000 image1
# rbd snap create --snap snap1 image1
root at cephtest1:~# rbd snap ls image1
ID	NAME		SIZE
4	snap1	1048576000


nexenta
-------
image1
image1 at snap1



----- Mail original ----- 

De: "Dietmar Maurer" <dietmar at proxmox.com> 
À: "Alexandre DERUMIER" <aderumier at odiso.com> 
Cc: pve-devel at pve.proxmox.com 
Envoyé: Jeudi 23 Août 2012 11:28:38 
Objet: RE: [pve-devel] kvm disk template implementation ideas 

> >>A simply storage scan does not work, because we also want a snapshot 
> >>of the VM configuration! 
> Ah ok, I miss that. I think you were talking about simple disk snapshot. 

No, we want full-featured VM snapshots ;-) 

> >>My idea was to extend the <vmid>.conf file to include a copy of the config 
> >>for each snapshot: 
> 
> >>----START---- 
> >># The current config is on top 
> >>mem: 1024 
> >>parent: snap2 
> >> 
> >>[snap3] 
> >>mem: 512 
> >>parent: snap1 
> >> 
> >>[snap2] 
> >>mem:128 
> >>parent: snap1 
> >> 
> >>[snap1] 
> >>mem: 256 
> 
> Yes, that can be great. 
> how do you see disk part ? 

Not sure if I understand your question correctly. The disks are part of the config, 
so each snapshot simply point to the snapshotted volume somehow: 

- either explicit: by using different volume names 
- or implicit: we generate the real snapshot volume names as F(volid, snapshotname) 

----impicit example---- 
# The current config is on top 
mem: 1024 
ide0: local:100/vm-100-disk-1.qcow2 
parent: snap1 

[snap1] 
mem: 256 
ide0: local:100/vm-100-disk-1.qcow2 
----END---- 


Or the other way: 

----expicit example---- 
# The current config is on top 
mem: 1024 
ide0: local:100/vm-100-disk-1.qcow2 
parent: snap1 

[snap1] 
mem: 256 
ide0: local:100/vm-snap1-100-disk-1.qcow2 
----END---- 





-- 

-- 



	

Alexandre D e rumier 

Ingénieur Systèmes et Réseaux 


Fixe : 03 20 68 88 85 

Fax : 03 20 68 90 88 


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