Windows Disk Configuration

Shadow Database pairs in Windows require four, or more, database partitions, two mirrored clean log partitions and two mirrored raw log partitions.

The top directory structure for each database must be enabled in its own partition, separate from the bulk of the database. Hence a pair of Shadow Databases requires at least four partitions, one for each top database directory (live and Shadow) and one or more for the main database structure of each database. The clean log partition must be on a resilient disk sub-system, for example mirrored disks or RAID disks.

The top database directory requires only a small partition as long as the temporary files directory tmp is moved from it. The top database directory normally requires a large amount of disk space to allow for temporary files created in tmp when doing large sorts. However, you can re-locate the tmp directory by defining the configuration parameter TempDir in the database configuration file. For example, the entry:

TempDir=C:\tmp

moves the tmp directory to the root partition. This reduces the disk space required by the database directory.

The tmp directory is normally cleared by the database daemon at boot time. This can be prevented by setting the ClearTempDir parameter in the database configuration file to any value other than Y. For example, the entry:

ClearTempDir=N

prevents tmp being cleared each time the database daemon is started.

The database directory partition and virtual partition for each half of the Shadow pair (live and Shadow) can be on the same set of disks. However, it is recommended that partitions for the live and Shadow databases must be located on different sets of disks.

Clean logs

The live and Shadow databases share the same clean log subdirectory. So, for example, if the clean log partition is mounted at e:\cleanlog, then Shadow pair dbase1 and dbase2, share the same clean log sub-directory e:\cleanlog\crime, where crime is the Shadow pair name. This can be carried out using option 1 on the Configuration and Setup  menu, described in Defining/Redefining a Shadow Database.