Re: [BackupPC-users] Backup of VM images

Les Mikesell <lesmikesell AT gmail DOT com> wrote on 06/07/2011 02:29:13 PM: > On 6/7/2011 1:04 PM, Timothy J Massey wrote: > > > > I'm not sure that really matters. The bandwidth usage will be similar to > > the difference between incrementals and fulls in a traditional BackupPC > > setup (i.e. you already have those same bandwidth issues: the VM's > > aren't going to make it worse). The biggest problem is that *every* > > backup is going to have to read 100% of the data every time. In other > > words, there really is no such thing as an incremental: an incremental > > and a full will read the same amount of data on both ends. > > But if bandwidth is the bottleneck and rsync succeeds at finding the > matching parts, having a closer matching file should be faster.

Sure, but is the difference compelling? Probably not. If it is, you're *way* too close to the margins anyway. What happens if the office has a busy day? You're going to run out of bandwidth anyway.

Part of this has to do with what your deltas look like, but there is *NO* difference between the bandwidth used backing up VM's as it is a normal filesystem-based backup. The deltas will be identical. And how many of us run daily fulls because we don't have the time for the increasing incrementals? I would venture to say *very* few...
> While the typical use would be to revive the latest copy after some sort > of disaster, I wouldn't rule out wanting older versions too. For > example if you had a security intrusion or an update-gone-wrong, you > might want to back out to something older and known-good.

Have you actually used virtualization? This sounds OK in theory, but not in practice! :)

That is what live snapshots are for. How long are you going to want to go back? Trust me, if you don't want to go back within a few hours, you are *NOT* going to want to go back even days later. In which case, your aged backups are *USELESS*.

With virtualization, not everything needs to be fixed by the BackupPC (or any other backup) hammer. That's the fun of having all those extra layers between the OS and the hardware! :) (And if you have real SAN hardware, it can get *really* fun: can you say thin-on-thin provisioning? It's like shorting stocks on margin! :) )

Timothy J. Massey


Out of the Box Solutions, Inc. Creative IT Solutions Made Simple! http://www.OutOfTheBoxSolutions.com tmassey AT obscorp DOT com		22108 Harper Ave. St. Clair Shores, MI 48080 Office: (800)750-4OBS (4627) Cell: (586)945-8796

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