[Techtalk] backup - tar

[Maria McKinley]

Thanks for all of the great advice and explanations Travis.  I didn't 
mean to say all when refering to the list of backup software, I meant 
lots, I should know to be more precise...

Maybe there is a way to write a script that would list all directories 
that first letter is a-m and output it to a file, same for n-z.  That 
would get around the human error element of dividing home in half. 
Unfortunately looking at man ls, I don't see an easy way of doing this.

cheers,
maria

Travis Casey wrote:
> On Wednesday 01 September 2004 19:15, Maria McKinley wrote:
> 
> 
>>Thanks everyone for all of your helpful advice. My short-term solution 
>>is using tar, but not using compression and dumping error messages to 
>>try to figure out what is going on.
>>
>>I did find a useful web site
>>
>>http://www.backupcentral.com/free-backup-software2.html
>>
>>that lists all of the free software available for unix.
> 
> 
> Well... that lists several pieces of free backup software, but nothing like 
> *all* of it.  You might want to check out www.linux-backup.net as well.  
> Also, O'Reilly's _Unix Backup and Recovery_ book has a lot of good advice.
> 
> 
>>I was looking at amanda, which looks like about the best around, but I
>>was confused by a statement they made:
>>
>>  AMANDA supports using more than one tape in a single run, but does not
>>yet split a dump image across tapes.
>>
>>Can someone explain the difference between using more than one tape in a
>>single run and splitting a dump image across tapes?  
> 
> 
> Think of it this way.  If I remember how Amanda works right, a "dump image" 
> is the backup image of a specific filesystem *or* set of directories and/or 
> files that you've told Amanda to back up as a "unit".
> 
> Amanda cannot split a "unit" across tapes -- but it can back up more than 
> one "unit" in a single run.
> 
> This has several implications.  Most importantly, if you have a filesystem 
> that's larger than can fit on a single tape, you'll have to break it down 
> into smaller units by specifying directories and/or files to back up.
> 
> Also of note, this can cause a waste of space on tape.  To take a worst-case 
> sort of scenario, if you're backing up six 60 GB filesystems, and you have 
> tapes that hold 100 GB, you're going to be wasting 40 GB on each tape.
> 
> 
>>I would have 
>>assumed these were the same things.  My situation is that all of the
>>data I want backed up does not fit on one tape.  Right now I backup
>>different parts of the system on different nights by cron (now it is
>>spread out even more than before, since I have stopped using zip to
>>compress!).  How much versatility do I have with Amanda?  Can I save
>>half of /home in one night?
> 
> 
> I *believe* Amanda will let you do this... but you'll have to specify the 
> breakdown.  E.g., if you have users ann, fred, george, and stacy, you could 
> tell it to back up /home/ann and /home/fred as one unit, and /home/george 
> and /home/stacy as another, and schedule those differently.  If I'm 
> remembering wrong, someone else please correct me!
> 
> The biggest problem here is that it's not automated... so if you add user 
> jill, you'll have to manually add /home/jill to one or the other, or create 
> a third "unit" for her.  And doing things manually is always subject to 
> error -- for example, when I first was typing the above, I accidentally put 
> 
> "back up /home/ann and /home/fred as one unit, and /home/fred 
> and /home/george as another"
> 
> Obviously, if I made that sort of mistake in actually setting things up, 
> Fred would be happy that he has *two* backups of his files every night, but 
> Stacy's not going to be happy with me at all when she loses some files!
> 
> 
>>While I am asking for backup advice... We are about to switch to a 1/2
>>TB raid array.  Right now we have an hp dlt 40/80GB backup tape system,
>>but we are going to have to upgrade this.  Any advice on how to backup a
>>  1/2 TB?
> 
> 
> Arg.  I'm facing the same kind of problem myself, compounded by the fact 
> that it's three 1/2 TB arrays, each of which is part of a database -- so 
> they all need to be backed up in sync to have a valid backup!
> 
> There are tape drives now that will store 200 GB per tape.  There may be 
> bigger ones than that, but I haven't heard of any that'll do 500 GB.  
> 
> Pretty much the only way to do it with tapes right now is to break it across 
> multiple tapes -- which'll require either doing it manually, as above, or 
> getting software that can do it for you.
> 
> The alternative is to back it up to other disks -- another, much larger RAID 
> array.  Some vendors are now selling products meant for exactly this sort 
> of thing, or you can do it yourself, by simply building a much bigger RAID 
> (I'd recommend at least two times as big, more likely three) and using 
> rdiff-backup, dirvish, or one of the scripts for using rsync for backups.
> 
> --
>        |\      _,,,---,,_     Travis S. Casey  <efindel at earthlink.net>
>  ZZzz  /,`.-'`'    -.  ;-;;,_   No one agrees with me.  Not even me.
>       |,4-  ) )-,_..;\ (  `'-' 
>      '---''(_/--'  `-'\_) 
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