jhalley wrote:... Yes, PDSE can require more "overhead" but are faster and can require less DASD with careful use of the 123 available extents. ...
Huh?? If PDSE uses more I/O and CPU - and it does, how can it be faster???
If PDSE uses more space - and it does - what does having more extents buy you??
jhalley wrote:... In the environment about which I spoke, service level requirements did not allow the continued use of PDS. We were also being pushed by software vendors who warned that their products would not perform well in our high volume environment unless we converted to PDSE. ...
Many PDS data sets are basically static. In my opinion, these data sets should not be PDSE. PDS data sets that do require substantial maintenance efforts because they are not especially static probably should be PDSE.
PDS directory search is extremely slow when the directory is very large. I won't try to deny this. In the last year or so I tried to measure this relative to PDSE, but failed. An unmentioned advantage of RAID type DASD is the code in the controller can effectively speed up PDS directory search if it's done right.
Similarly, PDS directory management - deleting and adding members - is also very slow when the directory is large. I don't know about similar issues with PDSE, though one would hope PDSE is better than PDS.