OSF DCE Administration Guide--Core Components

OSF DCE Administration Guide—Core Components
Eventually, all clearinghouses that contain a replica of this directory will detect the
presence of the CDS_UpgradeTo attribute and upgrade the CDS_ReplicaVersion
attribute on the appropriate replica. You can also use the following command on all
clearinghouses that are replicating the directory:
dcecp> clearinghouse verify clearinghouse-name
This command forces the server background thread to run, thereby freeing you to
perform other tasks until the job finishes. After you have verified all affected
clearinghouses, you will need to perform another skulk of the directory to finally set the
CSA_DirectoryVersion attribute to the appropriate value. The CDS_DirectoryVersion
attribute is not upgraded until all of the CDS_ReplicaVersion attribute values of all
replicas contain the new value.
18.2 Creating a Read-Only Replica
From time to time, you will want to create read-only replicas of directories. You create
read-only replicas of a directory for the following purposes:
• To distribute the information that is contained in the directory throughout your
network, and to make the information more accessible to users and applications at
other locations.
• To improve response time, especially in a namespace where users are dispersed over
long distances. You should create read-only replicas in clearinghouses that are
located near the user groups and applications that most frequently use the
information that is contained in the directory.
• To preserve a backup of the information that is contained in the master replica of the
directory. Maintaining multiple replicas ensures that the temporary loss of an
individual replica does not cause an interruption in service and that the loss of a
replica can be easily recovered. Even directories that store information used at only
one particular site should be replicated in at least one other clearinghouse, preferably
on a server at another location, so that a local failure at one site does not cause both
replicas to be unreachable at the same time. (See Chapter 17 for more information
on using directory replication as a means of backing up CDS information.)
Read-only replicas of directories are safe from alteration by users. Users can look up
information in a read-only replica, but they are not permitted to create new information
or modify existing information.
You create read-only replicas with the -replica option of the directory create command.
You should create the replicas in clearinghouses whose users need to access the
directory but do not need, or are not permitted, to update its contents.
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