# Administration Reference

## prdb.DB0 and prdb.DBSYS1

Purpose

Contain the Protection Database and associated log

Description

The prdb.DB0 file contains the Protection Database, which maps AFS user, machine, and group names to their respective IDs (AFS UIDs and GIDs) and tracks group memberships. The Protection Server (ptserver process) uses the information in the database to help the File Server grant data access to authorized users.

The prdb.DBSYS1 file is a log file in which the Protection Server logs each database operation before performing it. When an operation is interrupted, the Protection Server replays the log to complete the operation.

Both files are in binary format and reside in the /usr/afs/db directory on each of the cell's database server machines. When the Protection Server starts or restarts on a given machine, it establishes a connection with its peers and verifies that its copy of the database matches the copy on the other database server machines. If not, the Protection Servers call on AFS's distributed database technology, Ubik, to distribute to all of the machines the copy of the database with the highest version number.

Always use the commands in the pts suite to administer the Protection Database. It is advisable to create an archive copy of the database on a regular basis, using a tool such as the UNIX tar command.

Related Information

prdb_check

pts

ptserver

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