I always thought, and I may be wrong, that one of the main advantages to having either a PAV or individual minidisks was so that instead of having 1 queue for the device, you now have many. If your first I/O in the queue needs to do a physical I/O, then all the other I/Os wait. If most of the I/Os have their data already in cache, then those I/Os will be done at the same time as the physical I/O. I know we get about 95% of all our I/Os on MVS from cache.
Eric Bielefeld Sr. MVS Systems Programmer P&H Mining Equipment Milwaukee, WI 414-671-7849 [EMAIL PROTECTED] >>> [EMAIL PROTECTED] 03/26/03 02:33PM >>> Physically, that's true -- ultimately there is only one physical I/O in progress. However, by splitting up the disks into a larger number of small chunks and presenting them to Linux in the virtual machine configuration, the Linux system sees the smaller minidisks as separate volumes, and thus schedules multiple I/Os to what it thinks is multple devices. CP coordinates all the actual disk I/O and everybody wins. If you can, stripe the pieces across multiple physical voluems, but it's not as important. -- db David Boyes Sine Nomine Associates +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ This electronic mail transmission contains information from P & H Mining Equipment which is confidential, and is intended only for the use of the proper addressee. If you are not the intended recipient, please notify us immediately at the return address on this transmission, or by telephone at (414) 671-4400, and delete this message and any attachments from your system. Unauthorized use, copying, disclosing, distributing, or taking any action in reliance on the contents of this transmission is strictly prohibited and may be unlawful. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
