Troubleshooting guide

Appendix A, Functional Overview 237
Backup and Restore Functional Description
If the storage unit on which the files reside attaches to the master server, then bprd starts
the backup/restore manager on the master server. If the storage unit connects to a media
server, bprd starts the backup/restore manager on the media server.
The backup/restore manager starts the appropriate Media Manager process (bptm for
tape or optical or bpdm for disk) and uses the client daemon (bpcd) to establish a
connection between the NetBackup tar program on the client and bptm or bpdm on the
server.
The bptm (for tape or optical) or bpdm (for disk) process obtains the location of the data
(media ID or file path) and then starts retrieving data. During retrieval, the original bptm
or bpdm process stores the image block by block in shared memory. A second bptm or
bpdm process transmits the image to the client.
◆ If the storage is tape or optical, bptm includes the media ID in a tpreq command to
the Media Manager device daemon, ltid. The device daemon finds the physical
media and causes it to be mounted on an appropriate device. The bptm program
reads the image and directs it to the client, where the NetBackup tar program writes
it on the client disk.
◆ If the storage unit is disk, bpdm uses the file path in a read request to the system disk
manager. The image is then read from disk and transmitted to the client, where the
NetBackup tar program writes it on the client disk. Only the part of the image that is
required to satisfy the restore request is sent to the client, not necessarily the entire
backup image.