Many distributed databases supporting linearizability fail to provide consistent backups.

MongoDB's docs: "To capture a point-in-time backup from a sharded cluster you must stop all writes to the cluster"

Cassandra's docs: "To take a global snapshot, run the nodetool snapshot command using a parallel ssh utility ... This provides an eventually consistent backup. Although no one node is guaranteed to be consistent with its replica nodes at the time a snapshot is taken"

Riak's docs: "backups can become slightly inconsistent from node to node"

CockroachDB's docs: "The table data is dumped as it appears at the time that the command is started ... there is no guarantee that NOW() is monotonic in transaction order"

Does TiDB support consistent backups? Are there any docs covering how it is implemented?