Re: Backups - was: Re: LVM

[Lisi <lisi.reisz@gmail.com>]

On Tuesday 15 June 2010 14:40:44 Camaleón wrote:
> On Tue, 15 Jun 2010 11:32:15 +0100, Lisi wrote:
> > On Tuesday 15 June 2010 01:25:56 Andrew Sackville-West wrote:
> >> There are many many ways to make take backups beyond having a disk big
> >> enough to hold the data.
> >
> > Would you feel inclined to elaborate?  I'm trying to solve this problem
> > for my granddaughter's large HDD, and am not keen to have to buy a 300GB
> > external drive.  Tar would still require a fairly large medium. :-(
>
> I would differentiate between "backup" data and "archived" data.
>
> By "backup" I see a copy of the current files in the system and as per
> "archived" data I understand it as several snapshots of the data taken in
> different days and so holding different data.
>
> Backup usually takes less space than archival, but sometimes archival is
> necessary (a "must have" in a company).
>
> The most common procedure for a user's POV in order to get a data backup
> is by using a "differential" backup with some kind of compression. The
> first copy of the data will take all the files the user has selected to
> be backed up but the rest of the times the copy is only
> "differential" (only new or modified files are selected to be copied).
>
> This way (by using a differential backup strategy) you need less space in
> the medium (the first copy is big, but the rest of the differential
> copies are of small size and so the copy procedure is very quick).
>
> There are also those called "incremental" backups, but I find it a bit
> more complex to manage that "differential" ones, as per data restoration:
> with a differential backup yo only need the first big file and the last
> differential copy, but in order to restore from an incremental backup you
> need the first big file plus "all" the incremental ones).
>
> As per the programs to make backups... I still use "tar" (:-P) but
> "rsync" is said to be one of the most mentioned/preferred for this task.

Thanks for this.  I was originally responding to Andrew's saying:
<quote>
There are many many ways to make take backups beyond having a disk big
enough to hold the data.
</quote>

I can think of very few - and was interested in what he was thinking of.  
Incremental/differential backups are not really practical, since she will be 
at school.  A periodic dd (or Clonezilla?) of the whole drive and more 
frequent updates of her personal data (of which I understand that there is 
not much) would be the optimum, but a trifle pricey, so I am still looking at 
alternative possibilities.

Lisi