[NMLUG] Using weekly backup disk to store partial full backup as well?

[niosop at gmail.com (Matthew Bowie)]

This doesn't apply to what you're trying to do (as it does pretty much the
opposite of what you're trying to do), but it's a really cool program that
people might want to know about anyways.

A good method for full drive backups to another drive/partition (or even
another computer) is rdiff-backup.  It uses librsync so that only the
differences between the current file state and the last recorded file state
are transmitted (if going to a remote computer), and it stores compressed
rdiffs of the previous data.

I'm currently using it to backup an 80GB RAID1 partition (only 5GB used atm)
to a 400GB partition using a nightly cronjob.  Full backup takes < 1 minute,
and the rdiff is usually less than 10MB.  The data doesn't change much, but
when it does change it's important to have a backup of it.  At the current
rate of usage it should be possible to restore any file that ever existed on
the system to the state it was in at any date in the past 100 years
(overkill, I know).  Really handy if you find out that 3 weeks ago you
accidentally deleted a file you need, or if you need to see what a file
looked like on a particular date.

Once the system is in more active use, these numbers will change, but at
final steady state usage I'm estimating we'll have room for about 3 years of
daily snapshots on the 400GB partition.  Can't beat that  :)

-- 
Matthew Bowie
Programmer/IT Consultant
niosop at gmail.com

On 3/31/07, Steve Browne <sbrowne at ix.netcom.com> wrote:
>
> On Sat, 31 Mar 2007 12:21:19 -0700, you wrote:
>
> >I currently backup important files to DVD weekly. These files are 2G
> >in size total, so I "waste" ~2.7G on each DVD (these are DVD-Rs, so I
> >can't wipe/re-use them).
> >
> >How can I use this wasted space to do a complete backup? Example:
> >first week, backup the "first" 2.7G of my HD; second week, backup the
> >"second" 2.7G of my HD, and so on. Once the full HD is backed up (over
> >a number of weeks), roll over and backup the "first" 2.7G again, etc.
> >
> >My question here: given that the contents of my HD change constantly,
> >is there a program that will tell me WHICH 2.7G to backup each week?
> >
> >In other words, a program that will tell me one of the following:
> >
> >% "Here are 2.7G of files that you've never backed up to weekly DVDs.
> >Some of these are files that were created/changed in the last
> >week. Others are old files that you've just never backed up. I'm
> >choosing these files in a specific way and keeping track of them. Once
> >you've backed up these files, I'll choose a different 2.7G of files
> >next week (unless some of the files you backup today change between
> >now and next week)".
> >
> >% "There are only 1.0G of files that you've never backed up to weekly
> >DVD, and here they are. I've chosen an additional 1.7G of files that
> >you HAVE backed up, but they were backed up a long time ago, so it's a
> >good idea to back them up again".
> >
> >Obviously, 2.7G is an arbitrary number here, and it may vary week to
> >week. If my important files suddenly grow to 3G, I'll have only 1.7G
> >left for the partial complete backup files.
> >
> >Improvements would include compression, an exclude list, not backing
> >up two files w/ the same content, etc.
> >
> >I do make regular complete backups, but it'd be nice to have this
> >extra layer of protection.
> >
> >I considered writing something myself using find/ctime, but am too lazy!
>
> I don't have a suggestion  for your technique, but I want to note that
> I regularly back up my master HDD to a second HDD using Symantec Ghost
> 11.0 as it appears on Hiren's BootCD 8.9. Ghost will clone ext2, ext3
> and Reiser installations, and BootCD is self-booting via FreeDOS. It
> takes me 24 minutes to clone 56Gb. of data. An elegant solution.
>
> Steve
> Stephen B. Browne
> sbrowne at ix.netcom.com
> "Ubi bene, ibi patria."
>
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