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

[R. Daneel Olivaw]

Hi there,

While I was trying to find a solution to your problem, I ran across
some ways, but this would need heavy list comparing and in my mind
it ended up being more trouble than help. More over, restoring of files
would turn into some kind of nightmare ...

I'd suggest something really different:
one external usb drive (this may seem expensive, but compared to the
advantages, it may turn out much cheaper), mounted as ext3
filesystem. After that, use the *amazing* opensource "rsnapshot" tool.
This will alow you to have on your external drive a set of incremental,
totally accessible, fast and transportable backups.
- backup is fast
- backup is automatic
- backup can have as many increments (daily, weekly, monthly,
yearly ...) as you need, in a flexible manner (daily, plus 4 weekly,
plus 6 monthly, plus 1 yearly, ...)
- restoring is as easy as accessing the original data on your computer
- data is stored only once. any file that hasn't changed from one
'snapshot' to another is just hard-linked from the previous backup.
Means that you will have only one copy of each and any file you backed
up at any time.

The only drawback is that it cannot compress data (but this may be
achieved whith compressing filesystems, a thing I never tried out).
Besides, if yuo have too many files changing all the time, you may run
out of disk space, but with nowadays disk sizes, this should not be a
big trouble.

Now, if you insist on finding a dvd-backup solution, you may use the
same tool (rsnapshot) to make a local backup of your files (on the same
disk) and try progressivly to backup unchanged data from the snapshot
directory.

Well, I hope that helped anyway ;)

R. Daneel Olivaw,
The Human Robot Inside.

Le Sat, 31 Mar 2007 12:21:19 -0700
"Kelly Jones" <kelly.terry.jones at gmail.com> a écrit:

> 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!
> 
> -- 
> We're just a Bunch Of Regular Guys, a collective group that's trying
> to understand and assimilate technology. We feel that resistance to
> new ideas and technology is unwise and ultimately futile.
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