Hai Joshua:

Since level 1 backups everything since the last backup, that is level 0,
we will get replication of files (redundancy) irrespective of whether the
files are modified or not in the subsequent backups on the rest of the
days. In the sense on saturday, we will get files, a, b, c, d and e too. 

So tuesday: a, b
wed: a, b, c
thu: a, b, c, d and so on. (irrespective of whether the files are
modified or not. this will result in redundancy).

is there some mechanism to minimize it? y waste the tape.. .

true, i will go through the website too. it might be very useful indeed.


> Amanda does not append to tapes -- you'll need to change tapes each day.

so when will the tape drive1 get a chance to be overwritten? do we need to
relabel it again?


thanQ and regards,
nitesh




On Tue, 26 Nov 2002 at 7:30pm, Nitesh Kumar A. wrote

> I am really excited to know more about AMANDA now. 
> 
> What I understand is that, first amanda will take a level 0 backup (full
> backup) and then for the following days, it will take level 1. 

Usually.  If the level 1s get too big, it may "bump" them to 2s or higher.

> If suppose, amanda takes level 0 on sunday and then level 1, with
respect
> to 0 on mon/tue/wed/thu/fri/sat. 
> 
> Now I have files named a, b, c, d, e, etc on my filesystem. I have the
> full backup on sunday.
> 
> File "a" is modified on monday, so the level 1 backup on monday will
just
> have file "a".
> 
> File "b" is modified on tuesday, so the backup on tuesday will have just
> file "b" but not file "a" due to just level 1 backup.

That's incorrect.  A level 1 backs up everything changed since the last 
level 0.  So Tuesday night's backup will have "a" and "b".

> At some point of time, if I want to backup all the files, then I have to
> contact all the tape drives. Is this the case? Or will amanda tell me on
> which tape drives are these files located? How do I search for a
> particular file in the backup?

The program "amrecover" offers a ftp-like interface to the backups.  You 
tell it what files you want (and from which data), and it'll tell you what 
tapes you need.

> So if just file "a" is written into the tape drive1, how can we use the
> rest of the space on the tapedrive1?

Amanda does not append to tapes -- you'll need to change tapes each day.

For more, please go read the amanda chater from "Unix Backup & Recovery", 
available at <http://www.backupcentral.com/amanda.html> as well as the 
docs in the amanda tarball.  They'll explain a lot of these basic 
concepts.

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