Linux backup

[Peter Smith]

Malcolm Kay wrote:

>Some weeks ago I enquired here about 'dump' for
>use with ext3 file systems; and was strongly advised
>the Linux and 'dump' don't play well together.
>
>Reading the arguments including Linus Torvalds's comment
>'  Right now, the cpio/tar/xxx solutions are definitely 
>   the best ones, and will work on multiple filesystems 
>   (another limitation of "dump"). Whatever problems they 
>   have, they are still better than the _guaranteed_(*)  
>   data corruptions of "dump".'
>I was and am still convinced that 'dump' is not the way to
>go under linux.
>
>So I've spent some time scripting to marry in 'tar' 
>backups for recently acquired Linux machines with a 
>backup system that uses 'dump' for our unix machines.
>
>Yesterday I ran this for the first time on one of the Linux
>machines and found the backup aborted with the following 
>error in the log file:
>   /bin/tar: /home/thi/OM5438/test.hir1: file changed as we read it
>   /bin/tar: Error exit delayed from previous errors
>   Backup /data/pstar/root-0-z.tgz FAILED at Wed 18 Aug 2004 15:29:20 CST
>
>So 'dump' leads to corrupt backups, 'tar' leads to aborted backups.
>The abort message is undoubtably correct -- the file in question is a
>temporary file used during circuit simulation analysis. Individual 
>simululation runs can take from a few second upto a week. So it is not
>practical to close down everything for backup. (If it was then
>partitions could be dismounted for backup and the principal problem 
>espoused for 'dump' would disappear.) Such files are not crucial to the 
>backup. If tar simply skipped them or indicated that they were corrupt
>in the archive while correctly preserving the rest of the file system
>then this would be satisfactory -- but instead it aborts.
> 
>
>So is there someway to get 'tar' to continue when an odd file or two
>exhibits this sort of problem? I know about the option:
>  --ignore-failed-read
>              don't exit with non-zero status on unreadable files
>but from my interpretation of the man page it is not relevant to this
>problem.
>
>Does 'cpio' have the same problem?
>  
>
No. cpio version 2.5 does a lot of complaining about imaginary errors, 
but it does not abort, and AFAIK copies all files correctly.  I use it 
for all my backups from samba and win2k shares.

>Some have suggested 'amanda', but my understanding is that this is
>just a wrapper that optionally uses 'dump' or 'tar' so this seems
>to take us nowhere.
>
>What else is there out there for backup? I am not looking for a backup 
>system; just a reasonably reliable backup utility that can be used
>so that the linux machines can be incorporated into the backup system
>that works well for our unix machines.
>
>Some advice please.
>
>Malcolm Kay
>
>
>
>  
>
HTH,
Peter Smith