Managing performance in optical media libraries

Volume mounting and dismounting

Volume mounting and dismounting are important factors that affect optical performance. It takes approximately 8 to 15 seconds to remove a volume, store it in a slot, retrieve a new volume, and mount it. If you can minimize the number of volume mounts and dismounts that your application requires, optical performance will improve.

Drive contention

Performance can be severely affected by drive contention. The following conditions increase drive contention and should be avoided:

• Only one drive is available for use by applications libraries.
• Many optical processes are running that attempt to use different optical volumes at the same time.

Number of directories and files

Performance can be affected by having too few directories with too many files. Directories group related information to provide a means of quicker access. Typically, you get better performance from more directories with fewer files. Although there is no enforced limit on how many files there can be in a directory, you probably should not have more than 6000 for performance reasons.

File size

The size of a file has a direct effect on the amount of time it takes to read, write, or copy the file. In general, the larger the file, the longer the operation can be expected to take.

Add optical cartridge performance

Specifying *NO for the Rebuild Directory Index can improve the performance of Add Optical Cartridge (ADDOPTCTG) by deferring the build of the optical directory index until a later time.