Re: backup archive format saved to disk
Douglas Tutty wrote:
> I'm going to be backing up to a portable ruggedized hard drive.
> Currently, my backups end up in tar.bz2 format.
>
> It would be nice if there was some redundancy in the data stream to
> handle blocks that go bad while the drive is in storage (e.g. archive).
>
> How is this handled on tape? Is it built-into the hardware
> compression?
>
> Do I need to put a file system on a disk partition if I'm only saving
> one archive file or can I just write the archive to the partition
> directly (and read it back) as if it was a scsi tape?
>
> Is there an archive or compression format that includes the ability to
> not only detect errors but to correct them? (e.g. store ECC data
> elsewhere in the file) If there was, and I could write it directly to
> the disk, then that would solve the blocks-failing-while-drive-stored
> issue.
Now, to something completely different....
If data integrity is your concern, than maybe a better solution than
compression is to copy all your data with rsync or another backup tool
that 'mirrors' your files instead of packing them all together in one
large file. If something goes wrong with this large file you might loose
the backup of all your files. If something goes wrong with the
transmission of one file in the rsync case you will only 'loose' the
backup of that one file and just restart the rsync command.
Well, at least I much prefer to spend a bit more on storage and have all
my files copied individually. It adds the benefit that it is
straightforward to verify the integrity of the backup via 'diff -r'.
As far as redundancy is concerned I would prefer to use a second disk
(and while you are at it store it in a different location, miles away
from the other). I have one backup at home and another one at my
mother's house, adding several layers of security to my data.
Johannes
NB: Are you using a journal for your fs?
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