Bacula 1.34 User's Guide Chapter 14
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Data Spooling

Data Spooling

Bacula allows you to specify that you want the Storage daemon to initially write your data to disk and then subsequently to tape. This serves several important purposes. First it can take a long time for data to come in from the File daemon during an Incremental backup. If it is directly written to tape, the tape will start and stop or shoe-shine as it is often called causing tape wear. By first writing the data to disk, then writing it to tape, the tape can be kept in continual motion. The second major purpose is that while the spooled data is being written to the tape, the despooling process has exclusive use of the tape. This means that you can spool multiple simultaneous jobs to disk, then have them very efficiently despooled one at a time without having the data blocks from several jobs intermingled, thus substantially improving the time needed to restore files.

The remainder of this chapter explains the various directives that you can use in the spooling process.

Data Spooling Directives

The following directives can be used to control data spooling.
  • To turn on/off data spooling at the Job level in the Job resource in the Director's conf file (default no.

    SpoolData = yes/no

  • To override the Job specification in a Schedule Run directive in the Director's conf file.

    SpoolData = yes/no

  • To limit the maximum total size of the spooled data for a particular device. Specified in the Device resource of the Storage daemon's conf file (default unlimited).

    Maximum Spool Size = mmmm

  • To limit the maximum total size of the spooled data for a particular device for a single job. Specified in the Device Resource of the Storage daemon's conf file (default unlimited).

    Maximum Job Spool Size = mmmm

  • To specify the spool directory for a particular device. Specified in the Device Resource of the Storage daemon's conf file (default, the working directory).

    Spool Directory = directory

!!! MAJOR WARNING !!!

Please be very careful to exclude the spool directory from any backup, otherwise, your job will write enormous amounts of data to the Volume, and most probably terminate in error. This is simply because in attempting to backup the spool file, the backup data will be written a second time to the spool file, and so on ad infinum.


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Data Spooling
Bacula 1.34 User's Guide
The Network Backup Solution
Copyright © 2000-2004
Kern Sibbald and John Walker