When VM is running, snapshot operations have to be co-ordinated, once you have the snapshots in storage, it is possible to branch off other branches forking a VM and taking other snapshots on top of it. However, you can not have more than one parent.
The eventual big picture of it is a tree instead of a graph (introduced by multiple parents) Kelven On 8/6/12 5:13 PM, "Clayton Weise" <[email protected]> wrote: >Is it possible to have multiple parent snapshots for a VM/Volume? That >would be a way to get around the issue of bumping heads with other >snapshot processes. > >Sent from my mobile phone, please forgive any minor spelling or grammar >mistakes. > >-----Original Message----- >From: Alex Huang [[email protected]] >Received: Monday, 06 Aug 2012, 11:17am >To: [email protected] >[[email protected]] >Subject: RE: [Discuss] VM Snapshot > >+1. > >Some of the concepts in CloudStack follows too closely to what Amazon EC2 >APIs do. Snapshots (really backup as you pointed out) is one such >problem. > >In CloudStack storage, we should clearly distinguish between > >-Primary Storage Volume Access >-Snapshots (VM based) >-Backup (Moving snapshots off of primary storage and into a backing store) > >I caution that because CloudStack backup process does not account for >extra snapshots in the XenServer VHD chain, the changes this introduces >will be substantial. > >Edison is also planning to work in this area. Edison, can you discuss >what you have so far? > >--Alex > >> -----Original Message----- >> From: Mice Xia [mailto:[email protected]] >> Sent: Sunday, August 05, 2012 7:50 PM >> To: [email protected] >> Subject: [Discuss] VM Snapshot >> >> Hi, All, >> >> I¹d like to propose a new feature ŒVM snapshot¹. >> >> Currently CS support volume snapshot, which is an EC-2 like public cloud >> solution. >> IMO, it addresses problems like Œwhat if my volume lost or broke down, >>or >> what if my primary storage got an unrecoverable disruption¹, in other >>words, >> it¹s more like a backup solution, and it does take considerable long >>time to >> backup and restore, especially for large volumes which are unfortunately >> favored by customers. >> >> What I want to propose is snapshots on VM, just like what Xenserver and >> VMware ESXi do. >> It addresses requirement such as 'I want to save everything right now >>so that >> I can roll back in the future, and both operations can be done within >>seconds¹, >> mainly used for private cloud. >> >> Plan for the first stage consists of support in Xenserver and ESXi, and >>draft >> requirements are as followings: >> - Create VM snapshot. VM snapshot consists of: its CPU/memory status >>(for >> Xenserver it needs enterprise version), and volumes; service offerings. >> stored in PS, snapshots are removed when VM is expunged. >> - List snapshots for a specified VM >> - Rollback VM to a specified VM >> - Delete a specified snapshot >> - Does not conflict with volume snapshot >> - Create and restore should be done within seconds. >> >> Before I started off writing some documents on wiki and merge code, I'd >>like >> to welcome any comments and flames. >> >> Regards >> Mice
