> "diag 4k" = DIAG VDISK w/4k blocksize (check this one out!!!) > Rob,
You folks mentioned in section 5.5 of your Redbook the 512 byte format requirement. I think the reason this was done is because DIAG x'250' "simulates" larger blocksizes by simply returning multiples of 512 to fulfil the request. Unfortunately, CMS still stores the volume label based on a 512 byte blocksize so it still resides at offset 512 rather than the expected blocksize offset. This doesn't hurt anything as long as you don't care about seeing the correct volser. So I made a small modification to my patch and that was how I got the 4k blocksize with VDISK. Personally, I don't think the label is all that important when you get that much more throughput. ;-) But, since it's not 100% correct, I can see why IBM didn't allow for it. Leland
