Yes, everything you have described here is something I intend to create,
and might as well include in the tool itself. I'll add it to the roadmap ;-)
James
On 08/11/16 17:57, Niccolò Belli wrote:
On martedì 8 novembre 2016 12:38:48 CET, James Pharaoh wrote:
You can't deduplicate a read-only snapshot, but you can create
read-write snapshots from them, deduplicate those, and then recreate
the read-only ones. This is what I've done.
Since snapper creates hundreds of snapshots, isn't this something that
the deduplication software could do for me if I explicitely tell it to
do so? I mean momentarily switching the snapshot to rw in order to
deduplicate it, then switching it back to ro.
In theory, once this has been done once, it shouldn't have to be done
again, at least for those snapshots, unless you want to modify the
deduplication. It's probably a good idea to defragment files and
directories first, as well.
I can't defragment anything, because it would take too much free space
to do so with so many snapshots. Instead, the deduplication software
could defragment each file before calling the extent-same ioctl, that
would be feasible. Such a way you will not need hilarious amounts of
free space to defragment the fs.
It should be possible to deduplicate a read-only file to a read-write
one, but that's probably not worth the effort in many real-world use
cases.
This is exactly what I would expect a deduplication tool to do when it
encounters a ro snapshot, except when I explicitely tell it to
momentarily switch the snapshot to rw in order to deduplicate it.
Niccolo' Belli
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