HP 3000 customers have been advised by HP to consider the latest release of MPE/iX for their 3000s. This 7.5 version of the operating environment has been available for years; HP has already PowerPatched it - a process that consolidates patches into one superset - several times to add functionality and repair bugs.
But moving to 7.5 from 6.5 includes a few things to monitor. HP's 3000 peripherals expert Jim Hawkins recently advised a customer about volume management and IO changes. The counsel Hawkins shared looked like good advice for anyone making the change to 7.5, the last version of the MPE/iX which HP will ever build for the 3000:
The only “gotcha” with LDEV #1 suddenly having more space relates to the case where you have multiple volumes in your MPEXL_SYSTEM_VOLUME_SET. After the update LDEV #1 will look “empty” compared to other volumes and it will become the target of all disk allocations until its free space count is equal to that in the other volumes. (From 0-90% full across the set; after we reach 90% on all volumes the disk with the largest number of free sectors is the target). This applies for any MPE Volume set where you add a new disk (which is kind of what you’re doing).
In this case you might even see an effect on system performance in the short term — as XM and directory and VM and File system allocations will all be focused on LDEV #1. For this reason it is actually better to have LDEV #1 (or any master volume) be smaller than the other devices — it always gets the XM and directory traffic but, on average, will be less busy than the other disks for file system allocations so, on average, shouldn’t be a bottleneck. Your mileage may vary.
To prevent this kind of performance problem, after you’ve completed the 7.5 update activities and completed a full system back-up, you might consider "moving" a few (larger) accounts that reside on the MPEXL_SYSTEM_VOLUME_SET. One method would be to "STORE @[email protected],@[email protected];;PURGE;DIRECTORY" and "RESTORE" from the same tape. When you RESTORE the files MPE/iX will spread them across all the volumes as evenly as possible.
Part of the Large disk enhancements, MPEMXT4, “smooths” the extent spreading algorithm a bit more to help prevent “hot” disks. Call HP for this beta-test patch.
There's been talk for a long time about a "parking release" of MPE/iX for the 3000 as HP wraps up its 3000 operations. 7.5 looks like the most likely candidate for that release: the HP labs have developed enhancement patches for that version first, then moved to the 7.0 and 6.5 releases.