You may use the -f option multiple times on the same command line to tell BRU to use multiple files or multiple paths (which could be devices, for example) to store the archives. If multiple -f options are given, each path is added to a list of paths to cycle through each time a volume change is required. When the end of the list is reached, BRU automatically cycles back to the first path and waits for confirmation to continue the cycle again. Any input other than a carriage return will cause BRU to use the newly entered path and to abort the cycling for the remainder of the current run. This feature is known as device cycling.
The following example will do a full system backup (starting at root). It will first write data to tape1. When it is full, it will automatically continue on tape2. NOTE: When using this option all devices need to be the same size as the first device. BRU takes the size of the first device and uses that size for all other device when device cycling starts. If you specify a size of zero (0), BRU will then continue to write to each device until it receives an end of tape message. Then, BRU will switch to the new drive or device:
bru -cv -f tape1 -f tape2
To do a multiple device restore, the command is similar:
bru -xv -f tape1 -f tape2
BRU commands run from cron often use the device cycling feature. This allows BRU to get as much work done as possible before interaction is necessary. Device cycling can be used with the global brutab parameters MOUNTCMD and UNMOUNTCMD to allow writing to jukeboxes or tape libraries. If these parameters are used, then BRU will continually cycle through all the devices until it has completed reading or writing. It will not wait between devices or when it returns to the first device-any waits should be done by the shell scripts specified by MOUNTCMD and UNMOUNTCMD see Appendix K, “Using MOUNTCMD and UNMOUNTCMD”.