how many records you have for Virtual VOLSERs to define ?

Products

• Vtape Virtual Tape System

Issue/Introduction

Is there a way to know how many Virtual Volumes can fit in the BSDS and Global VCAT without expanding ?

Environment

Release : 12.6

Component : CA VTAPE

Resolution

Each record in the Global VCAT and BSDS is 4 KBs in size. 7298 of  those records are reserved for control information like the Recall Queues,  the Backstore Queues, etc. The rest of the records are for Virtual VOLSERs, one per record.

 

     If you have a data set with 7450 tracks. There are 12 4 KB records per  track, so you have 7450 x 12 or  89,400 records. 89400 - 7298 = 82102  records for Virtual VOLSERs. 

 

       However, these files are initialized and only the initialized space  can be used. If you allocated the file at 7450 tracks, but only initialized  it to 2000 tracks, then 2000 x 12 = 24000 records. 24000 - 7298 = 16702 records for Virtual VOLSERs. 

 

    How much space is actually intialized? These are  VSAM files so you do an IDCAMS LISTCAT and look for the High Allocated and  High Used RBA  values. High Allocate RBA or HARBA is how much space you have  allocated. High Used RBA or HURBA is  how much of that space is currently populated or initialized.

 

       Take the HURBA value and divide it by 4096 to get the number of  initialized records in your Global VCAT and BSDS. 

Subtract the 7298 control  records to determine how many records you have for Virtual  VOLSERs.