I'll definitely second that recommendation.

The other very useful bit of information offered by the "statistics"
option - apart from tape output rate -  is the number of tape i/o
errors - which could significantly affect your times.

If you save every stdlist that included the "statistics" option, you
could also easily compare no. of files stored, compression rate, i/o
errors, i/o rate, total bytes output (compressed & uncompressed),
etc.- and get a very accurate reading of exactly why your store times
are increasing.


At 08:24 PM 08-10-03, Hawkins, Jim (ESS TCE Q&W) wrote:
>No one seems to have yet mentioned the STATISTICS option, though
>it's mentioned often in connection with other threads.  Looking at
>STDLIST and comparing the transferred bytes and I/O rates and
>elapsed time probably would give you some clues.  If transferred
>bytes doesn't increase then check for new or changed jobs which
>might be stealing I/O or CPU bandwidth during back-up.   There also
>can be subtle affects around compression features.    Some folks
>with "extra" CPU can get better performance with STOREs COMPRESS
>options.  Others get better results with enabling only the hardware
>compression -- enabling both historically could do weird things like
>actually EXPAND your data (and on 7980s actually corrupt it IIRC, no
>hard reference I can point to.)   If my fingers remember correctly
>DEVCNTRL.MPEXL.TELESUP is one way to check on the hardware settings
>of the device.

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