[Discuss] VM backups

[gaf at blu.org (Jerry Feldman)]

On 06/07/2013 03:48 PM, Richard Pieri wrote:
> This can be a significant problem with virtualization. If you back up
> container files then you can easily restore the entire VM but you can't
> easily restore individual files. If you back up from within the VM then
> you can easily restore individual files but restoring the complete VM is
> largely impossible.
>
> The problem here isn't that doing backups is cumbersome. It's that
> treating the VM as a single monolithic entity is a poor practice. A
> typical Unix system has separate file systems for OS, configuration data
> (/etc), user data (/home), logs (/var) etc. If you apply that to virtual
> disks then you can have a vdisk for the OS, a vdisk for configuration, a
> vdisk for transient data and however many vdisks for user data that you
> need. This gives you the ability to tailor backup solutions for each
> kind of data and the associated vdisks:
>
> OS and transient data vdisks aren't backed up. There are master copies
> that can be dropped into place as needed. If keeping logs is a
> requirement then a central log server is a good way to handle them.
>
> Configuration data vdisks aren't backed up per se. A configuration
> management system or version control system makes for a better way to
> manage configuration data.
>
> Home directories are backed daily up from within the guests themselves.
> This is the only sane way to manage single file restores. Virtual disks
> may be cloned on a weekly or monthly basis to expedite disaster recovery.
>
> Other data should be handled on a case by case basis.
>
>
> I don't do this. All of my VMs are tiny things less than 5G each. I use
> rsnapshot to perform nightly backups of important bits of data to a
> central file server. The fact that they're all virtual machines is
> irrelevant to my backup procedures.
>
I'm running on a Vcenter/vSphere system. I have about 28 Linux systems, 
but all of the home directories and data are on a NAS, and I use TSM for 
the NAS (actually, TSM does not run on the NAS, it actually runs on a VM 
- not my choice), I used to run rsnapshot. I have 1 system that has 
local data, and it has its own TSM backup. And I have an Oracle DB that 
has its own backup to a local file system, then TSM backs that up. I use 
TSM because I have to. Fortunately all my VMs are essentially clones, 
but some have more memory or more vCPUs. Most of the important 
configuration data is stored in a common area that is backed up. In an 
ideal world where I would have more control, I would probably follow 
Richard's plan.

-- 
Jerry Feldman <gaf at blu.org>
Boston Linux and Unix
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