What is the BYTEPRC field in CA 1

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Article ID: 132283

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Updated On:

Products

CA 1 Tape Management CA 1 Tape Management - Copycat Utility CA 1 Tape Management - Add-On Options

Issue/Introduction



What is the BYTEPRC field in CA 1 Volume and DSNB records?
The ISPF Online Help just says:

 BYTEPRC    Actual percentage bytes written.  

Environment

Release:
Component: 1

Resolution

The BYTEPRC field was introduced in CA 1 Release 12.6 with PTF RO68743.
Following the description of the PTF explaining the new field:

>>>>
This enhancement adds a new 1-byte percentage field to both the TMC volume  
records (for file-1 information) and DSNB records (for file-n information). 
This new 1-byte percentage field indicates what percentage of the calculated
number of bytes written to the file were actually written. For example, if  
1,000 blocks of data was written with a 64k blocksize, taking block-count   
times block-size would indicate that 65Mb of data was written. But, if the  
actual size of the blocks written was only 47k on average, only 47Mb of     
data would actually reside on the tape. The new 1-byte percentage field in  
this case would contain a "72" indicating that 72% of the calculated data   
was actually written to the tape.                                           
                                                                            
SYMPTOMS:                                                                   
For files written with RECFM of U or VB, it is very likely that the         
blocksize specified during OPEN (or in the JCL) is only the reported value  
and may be different then the actual blocks of data written. This results   
in a calculated value of data written being different (sometimes smaller,   
sometimes larger) than the amount of data actually written to the tape.     
                                                                            
IMPACT:                                                                     
Reports that simply multiply block-count times block-size to obtain the     
total number of bytes written may be over or under reporting the true       
number of bytes written to tape.                                            
                                                                            
CIRCUMVENTION:                                                              
Analyze SMF21 data to obtain the true number of bytes written to each       
volume.                                                                     
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