Re: How to do differential backup with amanda?

On Fri May 9 2003 16:21, Joshua Baker-LePain wrote:
>On Fri, 9 May 2003 at 10:17pm, Wojciech Jedliczka wrote
>
>> > Look at the 'nofull' and 'incronly' dump strategies in the
>> > example amanda.conf.
>>
>> Unfortunately 'incronly' strategy will stop at level 9.
>
>"Only" level 9?!  At that point, you're going to need to read the
> backups off *10* tapes to get your whole filesystem back. 
> Thanks, but no thanks...

I'll byte. 4 questions for this old mans edification.

1.  To what does one "anchor" the backup to if the level 0 is never 
done.  It seems to me that even for all the so-called incremental 
levels, there would still be the base file that never got changed, 
and would therefore not be in any of the 9 "levels"  On the tape.

2. I just checked tar's manpage and found no mention of a method to 
dictate the level of 'incremental' used, yet I know its done, I've 
seen as high as a level 4 being done right here on my teeny home 
system.

3 & 4.  The usual method of controlling the dumpsize vs the tapesize 
is to use tar, and break the disklist into individual subdir DLE's 
that are only a fraction of the tape size.  Here, I'm backing up 
about 45 gigs of a 105 gig system (I've got "growing room") onto 1 
DDS2 tape per nightly run, using gzip best compression where its 
usefull.  Last night it did this synopsis:
-----------------
STATISTICS:
                          Total       Full      Daily
                        --------   --------   --------
Estimate Time (hrs:min)    0:22
Run Time (hrs:min)         3:40
Dump Time (hrs:min)        1:52       1:38       0:15
Output Size (meg)        2983.8     2709.4      274.4
Original Size (meg)      9195.1     8539.6      655.4
Avg Compressed Size (%)    31.9       31.7       35.1   
(level:#disks ...)
Filesystems Dumped           39          4         35   (1:33 2:1 
3:1)

As you can see, 9 gigs fit rather nicely on a 3.75 gig tape with 
plenty of room to spare.  Other nights the compression ratio isn't 
so high, with a 40% average I'd guess

Can you not do that?  And if not, why not?

-- 
Cheers, Gene
AMD K6-III@500mhz 320M
Athlon1600XP@1400mhz  512M
99.26% setiathome rank, not too shabby for a WV hillbilly
Yahoo.com attornies please note, additions to this message
by Gene Heskett are:
Copyright 2003 by Maurice Eugene Heskett, all rights reserved.