Cameron Simpson wrote:
On 19Mar2008 17:24, Tom Holroyd <tomh(a)kurage.nimh.nih.gov>
wrote:
| Show of hands: compress backups? Or 1:1 copy.
My choice? No per file compression. Let the storage substrate compress if
possible - eg modern tape drives do it on their own. Or if it doesn't, you
might compress the "archive of everything" file (eg a tar or dump file).
Otherwise you have to do "special" stuff on restore; it's untidy.
This position is a gross simplification of things of course.
Example: there are systems I backup with rsync to a new hardlinked tree from
yesterday's snapshot. Obviously this is 1:1, with incremental cost. It goes
to tape from an uncompressed tar file because the tape drive does some
compression.
If the storage device does not do compression, then from a
reliability standpoint, you are better off with per file compression
as opposed to total backup compression. The reason for this is that
if a compressed file gets corrupted, you lose that file, but if a
compressed back gets corrupted, you have a hard time recovering the
files after the corruption.
Mikkel
--
Do not meddle in the affairs of dragons,
for thou art crunchy and taste good with Ketchup!