Thanks Geoff, that's very helpful clarification.
The documentation on VM snapshots gives mixed messages. The CS documentation is non-committal about how snapshots should be used (and maybe it should be non-committal). The VMware documentation is very enthusiastic about the coolness of using 'snapshot chains' while at the same time pointing out all the things which can go wrong. My company has recently started to use CS to provide an IaaS platform to customers, and we find that they are attracted to VM snapshots because they are incremental, whereas there is limited possibility for incremental snapshots of volumes (we have only implemented CS with ESXi at the moment, which I understand does not support incremental). There are customers whose backup policy is to keep a daily backup of volumes for the last 30 days, so they are looking at significant storage costs for non-incremental snapshots. (Perhaps, we should educate them towards a smarter backup policy, but that is easier said than done.) Phillip On Fri, 2014-05-16 at 21:06 +0000, Geoff Higginbottom wrote: > Philip, > > > Simple answer is no. > > > A VM Snapshot should only be used as a temporary roll back option > prior to making a system change. After the planned changes are made, > and as soon as you confirm there have been no undesired adverse > affects, VM snapshots should be removed. > > > Snapshots are certainly not designed to be used as long term backups. > > > This is general virtualisation 'best practice' and not directly > related to CloudStack. > > > When a VM has an active VM Snapshot, CloudStack limits certain > features such as storage migration so another reason for not > maintaining long term VM snapshots. > > > On 16 May 2014, at 20:27, "Phillip Kent" <phillip.k...@gmail.com> > wrote: > > > Dear all, > > I have some questions about using VM snapshots. > > In principle, VM snapshots look like a very painless way for users to > keep backups of VMs (compared with the alternative of doing separate > volume snapshots of root disks, data volumes, etc). > > But when you look more into it > (http://kb.vmware.com/selfservice/microsites/search.do?cmd=displayKC&externalId=1015180) > you see that a lot of things can go wrong with snapshots. > > So I wondered if anyone has views or experiences on this, especially > where CloudStack is being used as IaaS for paying customers. I am > thinking about end users who only have access through the UI or API, > not > users who have root access to the hypervisors. Are VM snapshots a good > strategy for end users to keep regular backups of their VMs?? > > Thx Phillip > >
