A write server requires the following disk resources:
Raw device access to the shared disk devices that make up the IQ Store.
File system access to the Catalog Store files (.db and .log files) that comprise an Adaptive Server Anywhere database used to hold all of the catalog information for IQ.
Raw or file system access to the disk devices or files that make up the IQ Temporary Store.
File system access to the SQL Remote files (repDirs directory under the write server home directory.
Multiplex databases built with Sybase Central under
IQ version 12.4.3 and earlier may place the Catalog Store files
in directories under a shared top-level directory. This is no longer
needed.
To make recovery and failover easier, an IQ database administrator should keep careful notes about how all the disk and file system resources are set up in each server of the multiplex environment.
The IQ software is designed so that, as long as the four categories of disk resources hold contents that represent their state at a single point in time, the database server can restart and bring the database back to an operational state. In the case of the files or devices that make up the IQ Temporary Store, the server can even reconstitute the store if one or more devices fail, since the IQ Temporary Store holds no persistent data beyond what it can find in the Catalog Store.
The following subsections discuss several ways to use disk or tape resources to allow the return of the database to an operational condition.
