OSF DCE Administration Guide--Core Components

OSF DCE Administration Guide—Core Components
Figure 27-2. Disk Memory and Virtual Memory Copies of the Registry Database
Security
Server
Registry
Database
Registry
Database
Virtual Memory
Disk Storage
Each security server periodically saves its entire database from virtual memory to disk.
The database is stored in dcelocal/var/security/rgy_data.
27.5 Replicated Databases
The registry database can be replicated within its cell. Each instance of a security server
in a cell maintains a working copy of the database. Throughout this guide, the
combination of a security server and its data (the registry database) is referred to as a
replica. Typically, you create several replicas in a cell to enhance performance and
reliability.
The task of keeping the cell’s replicas consistent is handled automatically by the security
servers. Any changes that you make are automatically reflected in all replicas, as
described in the following section.
27.6 How Updates Are Handled
Updates are made to only one database, and the changes are propagated to all others.
While propagations are pending, all replicas are accessible even if they are not
completely up-to-date. In other words, even replicas to which the changes were not yet
applied are available. This replication mechanism ensures that all replicas remain
27 − 4 Tandem Computers Incorporated 124243