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Re: [Xen-users] Xen 4.0 feature request

On 07/07/09 16:38, Enrico Valsecchi wrote:
During my message in this thread, I have write that vmware
have a very powerfull tool that allow to try a consistent snapshot....
....I does not have idea that this tool work, but....
...it work!
And it's make vmware very powerfull, with a really and simple backup
regardless environment....

Xen's snapshot method is no less good than vmware's, it's just different. For VMware workstation you can have a nice gui where you have a snapshot and you can see hierarchies of snapshots and it's all really nice. For xen you have to do this "by hand" on the command line, but it's no less flexible. You could write a fancy gui to keep track of your snapshots though.

You could argue that a VMware snapshot is much more flexible because it doesn't require a complete copy of the disk and the memory of the running guest to be stored. Well, if you use one of the numerous copy-on-write mechanisms (qcow, lvm, zfs, btrfs, reflink, probably others) you can do the same, but xen doesn't need to implement that for you.

And then you've got the problem of getting the guest into a consistent shape for the snapshot because that's how you do backups. VMware seems to tout this quite a lot, but what's not mentioned is that is requires cooperation from the guest and the applications running in it. This is no different from vmware.

VMware has nice point and shoot (or point and click) mechanisms for taking snapshots and that makes it look really nice and powerful. When you get down to the nitty gritty, though, it doesn't have anything that xen doesn't. All that VMware has is the point and click UI ...


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