How much space do snapshots use in ZFS?
I created a pool and want to create a volume. I don't know how much space snapshots will occupy. Is there any way or formula exist to compute space requirements for snapshots?
The actual meta-data of snapshots are negligible.
As a copy-on-write file system, ZFS snapshots only require space for modified data; creating a snapshot does not immediately duplicate everything. If you have a snapshot of given size, and then add or modify files summing up to 100GB, the snapshot will "cost" you 100GB.
It might even be a little bit smaller because of compression and deduplication.
A snapshot initially takes a very negligible amount of space.
Its size grows later when existing data in the snapshotted dataset is updated or deleted.
The maximum size of a snapshot is the size of the original dataset unless compression and/or deduplication is enabled in which case you might have a snapshot smaller or larger than its parent dataset.