Veritas NetBackup™ Logging Reference Guide

The process flow for a SAN client restore is as follows (in the order presented).

• When the user starts a restore, NetBackup invokes the client's bprestore program that sends a request to the request daemon, bprd. This request identifies the files and client. The request daemon then uses bpcd (client daemon) to start the backup and restore manager (bpbrm).

  Note:

  To restore Backup Exec images, bpbrm invokes mtfrd.exe instead of tar32.exe on the clients. The server processes are the same as those used for NetBackup restores.

• If the disk or tape where the data resides attaches to the master server, then bprd starts the backup and restore manager on the master server. If the disk unit or tape unit connects to a media server, bprd starts the backup and restore manager on the media server.

• bpbrm starts bptm and provides bptm with the backup ID and the shmfat (shared memory) flag.

• bptm does the following:

  • Requests the SAN client information from the Job Manager service (nbjm).

  • Sends a restore request to the FT server process (nbftsrvr).

  • Sends a restore request to the FT client process on the client (nbftclnt). nbftclnt opens a Fibre Channel connection to nbftsrvr on the media server, allocates the shared memory, and writes the shared memory information to the backup ID file.

• bpbrm starts tar by means of bpcd and provides tar with the backup ID, socket information, and the shmfat (shared memory) flag.

• bptm does the following:

  • Reads the image from the storage device.

  • Creates a bptm child process. This process filters the backup image so that only the files that are selected for the restore are sent to the client.

  • Writes the image data to the shared buffer on the server.

  • When the buffer is full or the job is done, it sets the buffer flag (partial buffers may be sent to the client).

• tar does the following:

  • Sends the status and control information to bpbrm.

  • Reads the shared memory information from the local backup ID file (waits for the file to exist and become valid).

  • Waits for the buffer flag that indicates the data is ready to be read.

  • Reads the data from the buffer, extracts files, and restores them. When the shmfat (shared memory) flag is provided, tar considers the data to be already filtered.

• The FT Server process nbftsrvr waits for the shared memory buffer flag to be set. nbftsrvr then transfers the image data to the FT client (nbftclnt) shared memory buffer, and clears the buffer flag.

• The FT client (nbftclnt) waits for the data from nbftsrvr and writes the data to the shared memory buffer on the client. nbftclnt then sets the buffer flag.

• At the end of the job:

  • bptm informs tar and bpbrm that the job is complete.

  • bptm directs nbftclnt to close the Fibre Channel connection.

  • nbftclnt closes the Fibre Channel connection and deletes the BID file.