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Backup your Data¶
Even though Scylla is a fault-tolerant system, it is recommended to regularly back up the data to external storage. Backup is a per-node procedure. Make sure to back up each node in your cluster. The backup includes two procedures. These are:
Full Backup - copy the entire data of a node
Incremental - updates (delta) - flushed SSTables
Note
For cluster-wide backup and restore, see the ScyllaDB Manager documentation.
Full Backup - Snapshots¶
Snapshots are taken using nodetool snapshot. First, the command flushes the MemTables from memory to SSTables on disk, and afterward, it creates a hard link for each SSTable in each keyspace. With time, SSTables are compacted, but the hard link keeps a copy of each file. This takes up an increasing amount of disk space. It is important to clear space by clean unnecessary snapshots.
Procedure
1. Data can only be restored from a snapshot of the table schema, where data exists in a backup. Backup your schema with the following command:
$: cqlsh -e "DESC SCHEMA" > <schema_name.cql>For example:
$: cqlsh -e "DESC SCHEMA" > db_schema.cql2. Take a snapshot, including every keyspace you want to backup.
$ nodetool snapshot <KEYSPACE_NAME>For example:
$ nodetool snapshot mykeyspaceThe snapshot is created under Scylla data directory
/var/lib/scylla/dataIt will have the following structure:
keyspace_name/table_name-UUID/snapshots/snapshot_nameFor example:
/mykeyspace/team_roster-91cd2060f99d11e6a47a000000000000/snapshots/1487847672222From one of the nodes, recreate the schema. Repeat these steps for each node in the cluster.
Incremental Backup¶
Enabling the incremental backup (disabled by default) will create a hard-link from each SSTable, right after it is flushed, to a backups directory.
For a complete point in time backup, the following is required:
A snapshot
All incremental backups and commit logs from the time of the snapshot.
Make sure to delete unnecessary incremental backups. Scylla does not do this automatically.
Procedure
1. In the
/etc/scylla/scylla.yaml file set the incremental backups parameters to true and restart the Scylla service. Snapshot are created under Scylla data directory /var/lib/scylla/datawith the following structure:
keyspace_name/table_name-UUID/backups/backups_nameFor example:
/mykeyspace/team_roster-91cd2060f99d11e6a47a000000000000/backups/1437827672721