Allocation of FDS - FILES DATA SET

Products

• Disk Backup and Restore - MVS
• DISK BACKUP AND RESTORE- ADD-ON OPTIO
• DISK BACKUP AND RESTORE

Issue/Introduction

Could we have more information about the allocation of the FILES data set.

Resolution

The FILEINIT creates indices and data blocks for all defined sub files.

The number supplied in the FILEDEFN member entry is the maximum number of indexable records, not the physical capacity of the FDS. That depends on how many cylinders allocated to the FDS.

If the client knows how many records he wants and he must also calculate how much physical space is required.

Total number of tracks = (Subfile Capacity Requirements)/(Records per Track)

For example, DSNINDEX length is 256 number of bytes per track is 55,996.

So, the number of records per track is 218

If client wants to allocate 1 million records for DSNINDEX, then 1000000/218/15 need 305 cylinders.