Export a snapshot to another cluster

You can export any snapshot from one cluster to another. Exporting the snapshot copies the table's hfiles, logs, and the snapshot metadata, from the source cluster to the destination cluster.

Specify the -copy-from option to copy from a remote cluster to the local cluster or another remote cluster. If you do not specify the -copy-from option, the hbase.rootdir in the HBase configuration is used, which means that you are exporting from the current cluster. You must specify the -copy-to option, to specify the destination cluster.

The ExportSnapshot tool executes a MapReduce Job similar to distcp to copy files to the other cluster. It works at file-system level, so the HBase cluster can be offline.

Run ExportSnapshot as the hbase user or the user that owns the files. If the user, group, or permissions need to be different on the destination cluster than the source cluster, use the -chuser, -chgroup, or -chmod options as in the second example below, or be sure the destination directory has the correct permissions. In the following examples, replace the HDFS server path and port with the appropriate ones for your cluster.

To copy a snapshot called MySnapshot to an HBase cluster srv2 (hdfs://srv2:8020/hbase) using 16 mappers:

hbase org.apache.hadoop.hbase.snapshot.ExportSnapshot -snapshot MySnapshot -copy-to hdfs://srv2:<hdfs_port>/hbase -mappers 16

To export the snapshot and change the ownership of the files during the copy:

hbase org.apache.hadoop.hbase.snapshot.ExportSnapshot -snapshot MySnapshot -copy-to hdfs://srv2:<hdfs_port>/hbase -chuser MyUser -chgroup MyGroup -chmod 700 -mappers 16

You can also use the Java -D option in many tools to specify MapReduce or other configuration properties. For example, the following command copies MY_SNAPSHOT to hdfs://cluster2/hbase using groups of 10 hfiles per mapper:

hbase org.apache.hadoop.hbase.snapshot.ExportSnapshot -Dsnapshot.export.default.map.group=10 -snapshot MY_SNAPSHOT -copy-to hdfs://cluster2/hbase

(The number of mappers is calculated as TotalNumberOfHFiles/10.)

To export from one remote cluster to another remote cluster, specify both -copy-from and -copy-to parameters.

You can then reverse the direction to restore the snapshot back to the first remote cluster.

hbase org.apache.hadoop.hbase.snapshot.ExportSnapshot -snapshot snapshot-test -copy-from hdfs://machine1/hbase -copy-to hdfs://machine2/my-backup

To specify a different name for the snapshot on the target cluster, use the -target option.

hbase org.apache.hadoop.hbase.snapshot.ExportSnapshot -snapshot snapshot-test -copy-from hdfs://machine1/hbase -copy-to hdfs://machine2/my-backup -target new-snapshot