BACKUP OFTEN
BUT
Reorganize only when NEEDED!

I said a lot earlier in the general Q and A pages about the reliability of disk storage subsystems. This especially applies to the subsystems using RAID technologies to provide single point of failure avoidance.

You Still HAVE to BACKUP your data. Even if the disk devices don't fail, you or one of your collegues could have inadvertantly caused data to be overwritten or deleted or otherwise corrupted.

You don't need to reorganize often

Just because you backup the file, you need not restore it! Of course, you should ensure that the backup and restore procedures really work, but generally reorganization does not speed direct processing (the type that is usually done by on-line transactions). Think about how much batch window time is spent doing reorganizations, when simpler and quicker backups would be enough.

Particularly, when insert activity for a file hits one or more "hot spots", there is a high probability that CI and/or CA splits will occur during that insert activity. VSAM uses split activity to create free space within a file at the specific point where an insert must be made. If, because of clustered insert patterns, additional inserts occur in the same areas of the file, they will be able to exploit that free space efficiently.

On the other hand, consider that if you reorganize the file and leave insufficient free space at the "hot spots", VSAM will have to recreate the free space again through the split process.

A judicious balance among CI and CA freespace can accommodate random insert patterns with little or no clustering efficiently. Similarly, the VSAM CI and CA split processes make it possible to provide little to no distributed free space throughout the file, and to create free space at the point(s) of insertion.

BACKUP and RESTORE or reorganization processing can be a very significant part of critical batch window time. Trading a bit more disk space (by allocating VSAM CI and CA FREESPACE and by allowing CI and CA splits to remain in a file without reorganizing the file) can save critical batch window time and permit higher availability of on-line activity.