Clean Log File System
Clean logs are maintained in a dedicated clean log partition. On UNIX this can be within a mountable file system.
Caution
It is mandatory that the clean log partition is located on a disk which is separate from all standard partitions, swap partitions and logged databases.
A clean log file system comprises three levels, typically as in the diagram below. They are:
- A clean log directory. Using a mountable file system, this is the mount point for the file system.
- Clean log sub-directories. One for each database containing all clean logs for a particular database.
- Clean log files. One active log per database. Other used clean logs may be held on disk.
Clean Log File System Structure
Note: ON UNIX, typically, the clean log file system is below root (not mandatory). If the partition contains other file structures, the clean log directory may be further down the file system.
Use of a Log Disk
Normally a disk, designated the log disk, is dedicated to the raw and clean logs. However, in small systems other user partitions with low utilisation may also be held on the log disk. However, accessing of non-logging related data partitions on the log disk impairs the performance of Transaction Logging, particularly when using transaction boundaries.