On 2018-05-18 13:18, Niccolò Belli wrote:
On venerdì 18 maggio 2018 19:10:02 CEST, Austin S. Hemmelgarn wrote:
and also forces the people who have ridiculous numbers of snapshots to
deal with the memory usage or never defrag
Whoever has at least one snapshot is never going to defrag anyway,
unless he is willing to double the used space.
With a bit of work, it's possible to handle things sanely. You can
deduplicate data from snapshots, even if they are read-only (you need to
pass the `-A` option to duperemove and run it as root), so it's
perfectly reasonable to only defrag the main subvolume, and then
deduplicate the snapshots against that (so that they end up all being
reflinks to the main subvolume). Of course, this won't work if you're
short on space, but if you're dealing with snapshots, you should have
enough space that this will work (because even without defrag, it's
fully possible for something to cause the snapshots to suddenly take up
a lot more space).
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