Date: Wed, 22 Oct 2003 13:32:35 -0400 From: Ryan Sandridge <ryan@sandridge.org> To: freebsd-questions@freebsd.org Subject: strange dump (dark matter?) Message-ID: <B97C161A-04B5-11D8-AAFC-003065BBC750@sandridge.org>
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Hello all. I decided it was time to start doing backups. On Oct 7th, I did a full dump of /usr filesystem (among others), as such: # dump -0uan -f - /usr | gzip -7 > /tmp/20031007-usr-lvl0.dump.gz This seemed to work as expected, here is some info about the gz file: % gzip -l 20031007-usr-lvl0.dump.gz compressed uncompr. ratio uncompressed_name 507027476 1590855680 68.1% 20031007-usr-lvl0.dump Everything so far so good. Today (Oct 22) I tried an incremental dump, as such: # dump -5uan -f - /usr | gzip -7 > /tmp/20031022-usr-lvl5.dump.gz Here is where I start getting confused. While my other incremental backups today (/ and /var), seemed to be fine, the /usr dump was huge. Here is info about the gz file: % gzip -l 20031022-usr-lvl5.dump.gz compressed uncompr. ratio uncompressed_name 527112624 543600640 3.0% 20031022-usr-lvl5.dump This incremental backup is larger than the original full dump. Also notice that the compression ratio was 3.0%. When examining the list of files dumped, I don't see anything that could lead to a file size like this. A rough count shows that the backup should have been roughly 11MB uncompressed, compared to the 518MB uncompressed. I've tried reading up on both dump and gzip, but haven't found a clue. Perhaps I've discovered dark matter. Thanks, Ryan
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