How to Calculate and Estimate of the Amount of Data On a Tape Cartridge

Chris Flick, iTech Solutions

Run the DSPTAP *LABELS command to *PRINT. To determine how much save/restore data is on a cartridge, add all the file lengths and multiple by (block length less 4096). This gives you how many bytes are written to the tape.

Example:                               

Data File Label File
Sequence
Block
Format
Recg
Tech
Record
Length
Block
Length
SAV20200302 0000000001 *U P 00000 262144

                      

File
Length
Mvol
Ind
Mvol
Sequence
Date Created Expiration Date
000232033 CONT 0000000001 03/02/20 *PERM

232033 x (262144 – 4096) = 59,875,651,584 B

Data compression, if used, affects this figure; however, there is no way to calculate the effects.

In addition, if using a tape drive that is capable of optimum blocking and Use Optimum Block *YES is specified, there is no way to calculate how much more data can be written to the tape cartridge. Note: There is a minimum 20 percent margin of error when using this calculation. If the tape has sequences with different block lengths on it, you should group the different entries together. Do the calculations for each group/label, and add them all together (*) to get the total amount of data on the cartridge. 262144 0000232033

*Please note that you have to tally them up for each label. 

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