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Documentation → Configuration → Image metadata in etcd
Image metadata in etcd
Image list is stored in etcd in /vitastor/config/inode/<pool>/<inode> keys.
You can even create images manually:
etcdctl --endpoints=<etcd> put /vitastor/config/inode/<pool>/<inode> '{"name":"<name>","size":<size>[,"parent_id":<parent_inode_number>][,"readonly":true]}'
For example:
etcdctl --endpoints=http://10.115.0.10:2379/v3 put /vitastor/config/inode/1/1 '{"name":"testimg","size":2147483648}'
If you specify parent_id the image becomes a CoW clone. I.e. all writes go to the new inode and reads first check it
and then upper layers. You can then make parent readonly by updating its entry with "readonly":true for safety and
basically treat it as a snapshot.
So to create a snapshot you basically rename the previous upper layer (for example from testimg to testimg@0), make it readonly and create a new top layer with the original name (testimg) and the previous one as a parent.
vitastor-cli, K8s, OpenStack and other drivers also store the reverse mapping in /vitastor/index/image/<name> keys
in JSON format: {"id":<inode>,"pool_id":<pool>} and ID counters in /vitastor/index/maxid/<pool> as numbers
to simplify ID generation.