?

But regardless of whether you actually have physical "wasted" space on your real disk drive by using compressed virtual devices, if you choose a suboptimal block size, you still won't be making the most of the (even compressed) virtual devices you do allocate in your IOGEN, correct?? Granted there is a tradeoff, but say you really screw up and set up a terrible block size for your files that causes MVS to "waste" half of the "available" space of a given virtual DASD.? Compressed or non-compressed, that would still mean that MVS thinks that virtual device is "full" when it really isn't, it's just that the existing files are allocated terribly out of whack, and you'll end up having to create and maintain more virtual "devices" in your emulated mainframe's IOGEN than would normally be necessary, correct?

Just making sure I understand the ramifications of all this correctly,

Jeff.?