33 lines
1.3 KiB
Markdown
33 lines
1.3 KiB
Markdown
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[Documentation](../../README.md#documentation) → [Configuration](../config.en.md) → Image metadata in etcd
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-----
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[Читать на русском](inode.ru.md)
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# Image metadata in etcd
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Image list is stored in etcd in `/vitastor/config/inode/<pool>/<inode>` keys.
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You can even create images manually:
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```
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etcdctl --endpoints=<etcd> put /vitastor/config/inode/<pool>/<inode> '{"name":"<name>","size":<size>[,"parent_id":<parent_inode_number>][,"readonly":true]}'
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```
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For example:
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```
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etcdctl --endpoints=http://10.115.0.10:2379/v3 put /vitastor/config/inode/1/1 '{"name":"testimg","size":2147483648}'
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```
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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
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and then upper layers. You can then make parent readonly by updating its entry with `"readonly":true` for safety and
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basically treat it as a snapshot.
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So to create a snapshot you basically rename the previous upper layer (for example from testimg to testimg@0), make it readonly
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and create a new top layer with the original name (testimg) and the previous one as a parent.
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vitastor-cli, K8s, OpenStack and other drivers also store the reverse mapping in `/vitastor/index/image/<name>` keys
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in JSON format: `{"id":<inode>,"pool_id":<pool>}` and ID counters in `/vitastor/index/maxid/<pool>` as numbers
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to simplify ID generation.
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