Den tors 29 feb. 2024 kl 08:48 skrev garcetto <garcetto@xxxxxxxxx>: > > good morning, > i am trying to understand how ceph snapshot works. > i have read that snap are cow, which means if i am correct that if a new write update an exising block on a volume, the "old" block is copied to snap before overwrite it on original volume, am i right? > so, i creted a volume say 10 GB in size, empty, then created a snap. > so, coming to my doubt, why the snap is 10GB in size? it should be 0, because no new write update were done, am i right? This could be dependent on how you ask about the size. The snapshot should present itself as having 10G in size, if you as a consumer of it asks how large it is. If you run something like "rbd info <name>" and "rbd du <name>" you should be able to see the differences between its apparent size and how much storage it consumes on the cluster. rbd du -p glance-images 12345678-0e1e-4d51-abcd-484604d1df0a NAME PROVISIONED USED 12345678-0e1e-4d51-abcd-484604d1df0a@snap 40GiB 40GiB 12345678-0e1e-4d51-abcd-484604d1df0a 40GiB 0B <TOTAL> 40GiB 40GiB -- May the most significant bit of your life be positive. _______________________________________________ Dev mailing list -- dev@xxxxxxx To unsubscribe send an email to dev-leave@xxxxxxx
