On Thu, 20 Jun 2002 at 12:42pm, Steve Follmer wrote

> disk-to-disk backup is an idea whose time has come. I am prepared to
> believe that Amanda is wonderful (the Samba backup was a snap!), but it
> seems a bit old fashioned compared to say, Second Copy 2000.

I have no idea what Second Copy is (aside: quick look, ah, ok), but the 
target audiences are completely different.  Amanda is aimed at networks 
of *nix machines.  The beauty of amanda is that it scales easily from a 
single machine to several hundred, based on backup hardware.  And it is 
anything but old fashioned.

> What happens is if I just have one file:/backup/data directory, it gets
> erased and a full backup takes place every night. This might be
> acceptable but I'm exposed for the time that the backup takes place. Why
> doesn't amanda simply add incrementals to the one existing "tape"
> (file)?

On tape, appending is Bad.

> I probably must do what an earlier Bickle post described (more detail in
> the egroup)... "To rotate 'tapes', i recommend creating sub-directories
> and symbolically linking them to a 'data' subdirectory, which amlabel et
> al will look for. The directories are labelled like tapes. I name the
> subdirectories according to date, then i have a shell script which
> creates a new directory every night, makes the symlink, labels the tape
> then runs the backup.

Why not just use a "changer"?  That's the best way to do this.  I found 
this after a bit of looking:

http://www.mail-archive.com/[email protected]/msg07758.html

Define as many tapes as you want in your changer, and you'll get your 
incrementals.

> file-driver pure-disk backups. I also humbly suggest that the typical
> amanda user and typical equipment cost has changed over the decades of
> amanda, and that future versions could emphasize pure disk backup more. 

And I would humbly suggest that you're probably wrong.  Yes, there are 
more home users backing up small networks now, and disk is cheap (which is 
why file: exists at all).  But I would bet that the majority of users (and 
certainly the majority of amanda-backed-up data) use tape.  I consider 
myself a pretty small install, and I backup nearly 600GB of data using 
amanda.  In corporate (and edu) environments, tapes still have lots of 
advantages over disks, not the least of which is off-site storage.

-- 
Joshua Baker-LePain
Department of Biomedical Engineering
Duke University



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