On 5/5/2014 10:44 AM, Dawid Piotrowski wrote:
> Hello everyone
>
> I am preparing to implement Bacula on one of the servers I look after, 
> but being new to the Bacula subject I would like to ask for some 
> advisory from users more experienced.
>
> The server I mean to run Bacula on is Debian Wheezy-based and serves 
> as a host to several LVM-based Xen virtual machines running Wheezy as 
> well. Some of the VMs are database servers (mainly PostgreSQL). The 
> intended Bacula version is 5.2.6, available in Wheezy repositories.
>
> My first question concerns where it is more advisable to place Bacula 
> daemons: on the host system (and back up using LVM snapshots) or in 
> the virtual machines themselves? I guess it's easier to ensure data 
> consistency using LVM snapshots but I am afraid it would be much 
> harder to restore the machine in this way so I am inclined to install 
> Bacula in the VMs. However, wisdom comes from experience, so I ask 
> you, the more seasoned users: which of the ways is less likely to give 
> me headaches and what are possible 'gotchas' in each one? My intended 
> use of Bacula is being able to restore a failed VM back up quickly in 
> case of a disaster, rather than restoring single files. Any 
> recommendations would be more than welcome.

Keep in mind that creating a LVM snapshot of an active filesystem is 
never a valid strategy. For example, DB tables must be locked while the 
LVM snapshot is created. It only takes a brief time to create the 
snapshot, but the VM must somehow be made quiescent while the snapshot 
is created. The only safe way I'm aware of is to pause the VM, create 
the snapshot, then resume the VM. Once created, the snapshot will have 
to store copies of modified blocks for as long as it lives, (ie. until 
it is backed up with Bacula). This means you must make sure volume 
groups have sufficient unallocated space for the needed snapshots.  
Nevertheless, Bacula jobs can be configured to run scripts before and 
after the backup so the LVM snapshot creation can be automated.

That said, both methods are useful in different ways. LVM snapshots are 
great for disaster recovery or anything where restore can be an 
all-or-nothing process. On the other hand, for a file server VM where 
there is a need to restore that single file that a user accidentally 
deleted, LVM snapshots require more admin intervention. After restoring 
the snapshot it has to be mounted and the requested file found and 
somehow copied over to the VM. With bacula-fd running on the VM, 
restoring a subset of files/directories is easier and more 
fire-and-forget, because all that need be done is start the restore from 
the Bacula console.

I recommend installing bacula-fd on file server VMs and using LVM 
snapshots for other VMs.


------------------------------------------------------------------------------
Is your legacy SCM system holding you back? Join Perforce May 7 to find out:
• 3 signs your SCM is hindering your productivity
• Requirements for releasing software faster
• Expert tips and advice for migrating your SCM now
http://p.sf.net/sfu/perforce
_______________________________________________
Bacula-users mailing list
Bacula-users AT lists.sourceforge DOT net
https://lists.sourceforge.net/lists/listinfo/bacula-users