To restart an aborted backup, you must use the R option in the dump command.
f is an option that enables you to supply a device list.
comma-separated_device-list lets you direct the dump stream to output devices other than those originally designated in the failed dump. A restarted dump process uses this device list in the same way a regular dump would. Any device list that is valid to a regular dump will be valid in this case.
If a device list is not specified, the command defaults to the remainder of the devices listed but not yet consumed by the failed dump.
For example, suppose the following device list was supplied to the previous dump, which failed while writing to rst2a: rst0a,rst1a,rst2a,rst3a,rst4a.
The command will use rst3a,rst4a to complete the backup. However, if the original device list contained any non-rewinding (nrst) devices or any devices not supported, users are required to supply a new device list at the restart of the dump.
path is the path that is listed in the dump table (the output of the backup status command). If there are multiple entries (that is, entries with exactly the same path) the command prompts you to use the ID to restart the backup.
ID is the unique ID displayed by the backup status command.
You can use either path or ID in most cases.
The command starts rewriting the dump stream from the beginning of the tape file in which the previous dump was interrupted.