Mirroring and Replication

Since MapR-DB tables are created in volumes, mirroring of volumes lets you automatically replicate differential data in real-time across clusters. You might want mirror volumes to create disaster recovery solutions for databases or to provide read-only access to data from multiple locations.

Because MapR-DB does not require RegionServers to be reconstructed, databases can be brought up instantly on the mirrored site if the active site goes down.

Mirroring is a parallel operation, copying data directly from the nodes of one MapR cluster to the nodes in a remote MapR cluster. The contents of the volume are mirrored consistently, even if the files in the volume are being written to or deleted.

MapR captures only data that has changed at the file-block level since the last data transfer. After the data differential is identified, it is then compressed and transferred over the WAN to the recovery site, using very low network bandwidth. Finally, checksums are used to ensure data integrity across the two clusters. There is no performance penalty on the cluster because of mirroring.

See Working with Mirror Volumes for more details.