Am just in the throws of a VTS-B18/3590E, 2-ESCON, to a VTS-B20/3592- J1A, 4-ESCON upgrade. True it is not the latest and greatest but it moves us forward. You question has actually two parts to explain; front-end and back- end.
In my case the 2-ESCON channels were running almost to 100%. The VTS in general when it cache is nearing full (disk space), will throttle the channels back. The VTS-B18 was overpowered (processor busy) and could not send the command back to the z9BC to slow up. Thus the channel subsystem got Channel Checks, had to go through error recovery, etc, (stopping the channels), and eventually started back up. In the meantime the VTS was catching up destaging or staging, etc. From the sounds of your case the channels are a humming and that to me is good. If you look for Channel Checks and see them, this would be a sign your VTS is underpowered. With the installation of the VTS-B20 I am assured processor power is no problem and besides there is double or quadruple the cache size. Plus I go from 2- ESCON to 4-ESCON and am assured that will not flood the VTS processor. On the back-end side I have the IBM 3590E which are SCSI attached, offload and also stage to the cache disk. The smaller the disk size, the more of the back (reads) and forth (writes) of data depending . With the VTS-B20, I get 4 times the space and Fibre connections to the drives making that process faster. With all this it will position me for the next move to FICON and onto the 3494- ATL drives to upgrade. Agree you need to look at some performance data and others have made suggestions. Jim ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
