If you try to create an LVM snapshot with
lvm lvcreate -s -n snapname -L 100G myvg
and it fails with
Unable to create a snapshot smaller than 2 chunks.
... it's probably actually trying to tell you "I don't have 100GB free on this VG, allocate a smaller snapshot". It's choosing to phrase it creatively.
You'll only get this error if you're within a certain margin of sizes: much too big and it'll tell you a rather clearer:
Volume group "myvg" has insufficient free space (1000 extents): 2000 required.
so it's really just a bit of a limitation or cosmetic bug.
It's not very Google-able though, hence this post. Next time I hit this error I'll search for it and find my own writing, having completely forgotten that I was involved in a case where the team I was on saw (more…)