What is the BYTEPRC field in CA 1 Volume and DSNB records? The ISPF Online Help just says:
BYTEPRC Actual percentage bytes written.
Release: Component: 1
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. <<<<