For the most part, Ubik operates without human intervention. However, it does depend on other DCE facilities and services for some things. The following list describes the interaction between Ubik and the remainder of DCE. It also provides an overview of the configuration information necessary for Ubik to operate properly. Configuring Database Server Machines for Ubik discusses the database server configuration steps required for Ubik to function properly.
· Ubik relies on DTS to synchronize the clocks on server machines that house copies of a replicated database. Ubik coordinators must agree on the time; clock differences among Ubik sites can cause them to believe they are no longer in contact with each other, even if they are operating correctly. If a site falls out of touch, it may try to elect a new synchronization site or refuse to give out information. You can prevent such service outages by using DTS to synchronize the clocks on database server machines.
· Ubik relies on the Security Service for secure communications between all Fileset Database machines (machines that house the FLDB) and Backup Database machines (machines that house the Backup Database). Each type of database server has its own security group, of which all machines that house a copy of that type of database must be members. A machine's membership in this group enables the Ubik coordinator on that machine to communicate with the Ubik coordinators on the other database servers of that type, thus allowing the coordinator to participate in Ubik elections.
Abbreviated forms of the DFS server principals of all Fileset Database machines must be listed in the subsys/dce/dfs-fs-servers group in the Registry Database. Similarly, abbreviated forms of the DFS server principals of all Backup Database machines must be listed in the subsys/dce/dfs-bak-servers group in the Registry Database. To view the members of either of these security groups, use the dcecp group list command.
A machine's DFS server principal is of the form /.../cellname/hosts/hostname/dfs-server. The abbreviated form of a machine's DFS server principal is of the form hosts/hostname/dfs-server. For example, in the cell named abc.com, the abbreviated server principals of all Fileset Database machines are listed in subsys/dce/dfs-fs-servers in the form hosts/hostname/dfs-server.
· Ubik relies on CDS for a complete list of all Fileset Database and Backup Database machines. Each type of database server has its own RPC server group in CDS. Ubik examines the machines listed in the appropriate RPC group to determine how many sites constitute a majority and where to send votes in the event of an election.
The names of the RPC bindings of all Fileset Database machines must be listed in the RPC group in CDS at /.../cellname/fs, the junction to the DFS filespace. Likewise, the names of the RPC bindings of all Backup Database machines must be listed in the RPC group in CDS at /.../cellname/subsys/dce/dfs/bak. To view the members of either of these RPC server groups, use the dcecp rpcgroup list command.
The name of a machine's RPC binding is of the form /.../cellname/hosts/hostname/self. For example, in the cell named abc.com, the names of the RPC bindings of all Fileset Database machines are listed in /.../abc.com/fs in the form /.../abc.com/hosts/hostname/self.
Note: In a server machine's DFS server principal or the name of its RPC binding, the element that follows the cellname component is not considered to be well known; for example, hosts could be dfs-hosts. However, the string used for the element must be applied consistently to all such names in a cell.
In addition, the /.../cellname/fs and /.../cellname/subsys/dce/dfs/bak names in CDS are not considered to be well known; either can be changed during installation and configuration of a cell. Conversely, the names of the subsys/dce/dfs-fs-servers and subsys/dce/dfs-bak-servers groups are well known and cannot be changed.