Back Up and Restore Databend Meta Service Cluster

This guideline will introduce how to back up and restore the meta service cluster data.

Export Data From Meta Service

Shutdown the databend-meta service.

Then export sled DB from the dir(<your_meta_dir>) in which the databend-meta stores meta to a local file output_fn, in multi-line JSON format. E.g., every line in the output file is a JSON of an exported key-value record.

# cargo build --bin databend-metactl

./target/debug/databend-metactl --export --raft-dir "<your_meta_dir>" > "<output_fn>"

# tail "<output_fn>"
# ["state_machine/0",{"Nodes":{"key":2,"value":{"name":"","endpoint":{"addr":"localhost","port":28203}}}}]
# ["state_machine/0",{"Nodes":{"key":3,"value":{"name":"","endpoint":{"addr":"localhost","port":28303}}}}]
# ["state_machine/0",{"StateMachineMeta":{"key":"LastApplied","value":{"LogId":{"term":1,"index":378}}}}]
# ["state_machine/0",{"StateMachineMeta":{"key":"Initialized","value":{"Bool":true}}}]
# ...

Restore a databend-meta

The following command rebuild a meta service db in <your_meta_dir> from exported metadata:

cat "<output_fn>" | ./target/debug/databend-metactl --import --raft-dir "<your_meta_dir>"

databend-meta --raft-dir "<your_meta_dir>" ...

Caveat: Data in <your_meta_dir> will be cleared.