ADSTAR Distributed Storage Manager Version 3 Release 1 Performance Tuning Guide
The DIRMc option specifies the management class you want ADSM to use for 
directories. The main benefit of managing directories separately from their 
files is faster file restore throughput from tape. The directories should be 
stored in a DASD storage pool. The DASD storage pool should not require a lot 
of space, since directories are typically very small. 

In a restore operation, ADSM first restores the directories and then the files. 
This order of events can have a negative impact on restore from tape. For 
example, if you have slow tape storage pools, i.e., 8mm tape drives, and the 
directories are stored on tape with the files, a large amount of time can be 
spent searching and mounting tapes to restore the directories. This time is 
saved with the DIRMc option by storing the directories in a DASD storage pool. 

Leo Humar
LCS Pty Ltd
lhumar AT bigpond.net DOT au

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