Mirroring With The DRBD Driver

• The DRBD driver supports synchronous mirroring of data between two different machines.
• You load the driver on two machines, and define remote mirrors for "local" disks ("local" can also be on a SAN or a NAS).
• When the local machine gets an I/O write request, it will perform it locally, and also send a copy to the remote machine (via the LAN).
• Only when the I/O request completed on both local and remote devices, the result will be returned to the calling application (or file-system).
• DRBD is useful under the control of a high-availability cluster software, such as heartbeat.

Originally written by guy keren