Re: backup archive format saved to disk
Johannes Wiedersich wrote:
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
[snip]
My understanding of the BZ2 format is that it compresses individual
blocks independently, and that the loss of a block will not compromize
the entire archive, only those files which are contained in a given
block.
Your other points are (as usual) well taken.
Mike
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