|
HP OpenVMS Systemsask the wizard |
|
The Question is: Should memory utilization peaking at 96% with no swapping and very little page faulting be of concern? This is an Alpha 8400 in a 3 node CI Cluster with 4GB of memory and 6 processors. Does digital have guidelines on memory utilization thresholds for an Alpha Server running in this type of environment? The Answer is : If the system is not swapping and has minimal pagefaulting and -- most importantly -- is meeting your performance expectations, then seeing nearly complete memory usage will indicate that OpenVMS is making the best use of all available memory. Various caches can fill available memory, trading increased memory use for reduced I/O load. Relatively low amounts of memory on the freelist can reduce the general performance of image activations, and can result in system overhead to release memory should an application require additional memory. Given your statements around the lack of swapping and minimal pagefaulting, this does not appear to be the case at your site. As a guideline, system parameters are established using AUTOGEN, after having cleaned out any cruft that has built up in MODPARAMS.DAT over the years -- entries for applications that are no longer used, tuning tweaks from ancient OpenVMS versions, and any absolute parameter settings that can be switched over to ADD_, MIN_, or MAX_ settings. The Guide to OpenVMS Performance Management contains information on tuning, on various associated considerations, and on appropriate use of MODPARAMS and AUTOGEN. The Wizard typically expects only small improvements in performance using manual system tuning steps over what AUTOGEN will provide -- application tuning and hardware upgrades usually provide more economical system performance improvements, particularly when one considers the effort required to gather baseline performance, consider various avenues of potential improvements, and to then track the actual effects of the performance "tweaks".
|