On Mon, Jan 18, 2010 at 06:20:27PM +0100, Leonardo Canducci wrote: > I'm using rsync -aHS to backup some stuff (mostly jpgs and > docs from my home) to an external usb hard drive (same > ext3 fs). snip > I've noticed some dir size doesn't match: snip
Ext3 has a limitation in the way it stores directory
entries: the space allocated for a directories contents can
grow but not shrink. You can test this by creating a new
directory, adding a single file, checking the size of the
directory, then creating a large number of files ("for i in
`seq 1 100000000`; do mktemp --tmpdir=<testdir>& done" or
similar): check the size again. Then remove all the files,
re-check.
Thus checking the size of the source and destination folders
is not useful if the rate of change/growth for the folders
will differ (which for an active partition and a relatively
inactive backup partition will always be the case). The most
reliable (imho) way to ensure that you have an accurate copy
is an rsync dry run:
rsync -van --delete ./src ./dest
(or similar). If it says it will make no changes, you're ok.
--
Jon Dowland
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