Date: Tue, 16 Nov 2004 18:22:29 -0500 From: David Gilbert <dgilbert@dclg.ca> To: freebsd-stable@freebsd.org Subject: Different snapshot sizes. Message-ID: <16794.35765.800111.518475@canoe.dclg.ca>
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I'm somewhat confused. When I take snapshots, offtimes, they seem to be different sizes. I have a system that has two 120 Gig disks that are vinum (now gvinum) raid1'd. On that I have a root, swap, usr, var and 'u' partitions. All vinum created. As one (of several) backup policies, we take three filesystem snapshots per day, and progressively delete them such that the oldest snapshot we keep is about 30 days old. But the snapshots are often different sizes. This strikes me as odd, as I understood the "format" of a snapshot was to be the same as the "format" of the partition itself --- so they should all have the same size as the physical partition. An example: Making snapshot /usr/snap/20041116_180000 done. total 193248 -r--r----- 1 root operator 6442451256 Nov 16 17:32 20041116_094346 -r--r----- 1 root operator 6442451256 Nov 16 18:00 20041116_120001 -r--r----- 1 root operator 6442451264 Nov 16 18:00 20041116_180000 ... the script above calls mksnap_ffs and then ls -l's the directory. Note that the last snapshot is 8 bytes larger. Very odd. It's not divisible by 512, but then neither are the other two. At any rate, this all wouldn't worry me if the server didn't crash with some regularity ... which it does. In fact, the /var partition gets the widest variety of snapshot sizes ... so I've disabled snapshots there alltogether. Dave. -- ============================================================================ |David Gilbert, Independent Contractor. | Two things can only be | |Mail: dave@daveg.ca | equal if and only if they | |http://daveg.ca | are precisely opposite. | =========================================================GLO================
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