Re: CentOS Server Backup Options: at runlevel 5? ... w/snapshot

[ken <gebser@xxxxxxxxxxxx>]

On 03/14/2012 02:59 PM Nataraj wrote:
> On 03/14/2012 08:43 AM, Les Mikesell wrote:
>> On Wed, Mar 14, 2012 at 10:10 AM, ken <gebser@xxxxxxxxxxxx> wrote:
>>> What (FOSS) backup apps can back up a system running at level 3/5?
>> Almost all backup methods except raw partition/disk images will work
>> with the system running.  You aren't guaranteed that files will be in
>> a consistent state when restored, but the OS itself is fairly sure to
>> work and databases and similar apps usually have their own ways to do
>> live consistent snapshots.
>>
> I find that LVM snapshots are useful to insure data integrity.  for
> example, I backup my mysql databases by stopping the mysql server,
> taking an LVM snapshot and restarting it.  The whole snapshot process
> probably takes less then 15 seconds.  Then I backup the snapshot LVM and
> it doesn't matter how long it takes.  You must make sure that your
> snapshot volume is large enough that you won't run out of space before
> deleting the snapshot.
> 
> Nataraj

Thanks for the tip.  The details of how a snapshot works has long evaded 
me.  For example, when files are open but unsaved, what is written to 
the snapshot...?  And is the entire contents of a file recorded by the 
snapshot... or something else?

tia.
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