Note on using cpdup with HAMMER1 snapshots
dillon at apollo.backplane.com
Mon Dec 17 14:30:34 PST 2012
Just a side note here on using cpdup with snapshots, as it has been
brought up a few times on IRC and in bug reports.
HAMMER1 snapshots do not have reliable mtime's, because mtime updates
are not snapshotted. This can throw cpdup off so my recommendation for
anyone doing a cpdup from a snapshot to a target which already exists
is to *ALWAYS* use the -VV option to cpdup. Note the uppercase.
The -VV option tells cpdup to ignore mtime entirely and to verify two
seemingly identical files by actuallying comparing them before deciding
whether to copy it or not. It won't be incremental this way since it
has to read the entirety of the source and target trees, but it will
still avoid unnecessary writing to the media (good if the target is a
SSD), and will result in a reliable copy when the source is a HAMMER1
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