[linux-lvm] faster snapshot creation?

Eric Toombs ewtoombs at uwaterloo.ca
Sat Feb 22 11:58:53 UTC 2020

Snapshot creation is already pretty fast:

> $ time sudo lvcreate --size 512M --snapshot --name snap /dev/testdbs/template 
>   Logical volume "snap" created.
> 0.03user 0.05system 0:00.46elapsed 18%CPU (0avgtext+0avgdata 28916maxresident)k
> 768inputs+9828outputs (0major+6315minor)pagefaults 0swaps

That's about half a second in real time. But I have a scenario that
would benefit from it being even faster. I'm doing many small unit tests
starting from a template filesystem. I do the snapshot, run the unit
test on the snapshot, then delete the snapshot afterwards using
lvremove. Each unit test, though, takes much less than a second to run
(often on the order of 10ms), so most of the time is being spent making
these snapshots.

So, is there a sort of "dumber" way of making these snapshots, maybe by
changing the allocation algorithm or something?

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