Am Mittwoch, 6. August 2014, 13:09:39 schrieb jcsl:
[...] I want to make backup a partition and I want to compress the data.
What do you mean by "partition" exactly? An exact image of the partition? Or all files of the file system on that partition?
I'm worried about the possibility of the compressed files being damaged when I try to restore then. I've read that in compressed tarball you cannot recover any data after a single damaged bit.
That is the worst case scenario. Compression tools often use a limited block size (bzip2 uses a default block size of 900,000 bytes) and check sums. Thus, the next undamaged block could be found and the rest of the archive might be recovered. E.g., bzip2 has a tool for recovery: | 2.6. RECOVERING DATA FROM DAMAGED FILES | [...] | bzip2recover should be of most use dealing with large .bz2 files, as these | will contain many blocks. It is clearly futile to use it on damaged | single-block files, since a damaged block cannot be recovered. If you wish | to minimise any potential data loss through media or transmission errors, | you might consider compressing with a smaller block size. http://www.bzip.org/1.0.5/bzip2-manual-1.0.5.html#recovering
I'm looking for tools like rar that creates extra recovery files. What options are available?
First, if you want to backup all files of a partition, you could compress each file individually. Thus, a single damaged bit may affect one file at most: http://dar.linux.free.fr/doc/FAQ.html#compression dar can use Parchive to add parity files: http://dar.linux.free.fr/doc/usage_notes.html#Parchive
What I've found at
https://en.wikipedia.org/wiki/Comparison_of_archive_formats#Comparison
and available in the repositories are DAR and rar.
I used dar to compress and encrypt my backups.
[...] I haven't used any of these except rar and I don't know if the have some kind of problems.
I bet they will. :) However, the question is whether you will ever run into them.
And I don't know how other compression tools like gzip and bzip behave in case of file damage.
It looks like corrupted gzip files are the worst case scenario you described above.
I have used dd + tar.gz previously to make backups but I'm not sure if it is a good option anymore. Any hints? [...]
If it is sufficient to backup the individual files of a native linux partition (e.g., ext2/3/4) dar & par should do the trick. Gruß Jan -- Acceptance without proof is the fundamental characteristic of all religions. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org