HP is very stable.
As much as I like to "bash" some of my co-workers (Solaris ans AIX) - just about any system can be made to have high stability.
Myself, I prefer HP-UX - been Unix admin since 1993, worked with HP-UX, AIX, Solaris, Irix, Linux. Over that time, I have found HP to be the most reliable, best support.
Ton of posts on: Buffer Cache
There are 2 main kernel parameters:
dbc_max_pct (default 50%) and dbc_min_pct (5%).
How the Buffer Cache Grows:
As the kernel reads in files from the file system, it will try to store data in the buffer cache. If memory is available, and the buffer cache has not reached its maximum size, the kernel will grow the buffer cache to make room for the new data. As long as there is memory available, the kernel will keep growing the buffer cache until it reaches its max size (50% by default).
For performance reasons, you want the buffer cache hit ratio on reads to be higher then 90%.
sar -b and watch %rcache
Now what should you set your to? That depends on what you are running on the box. If Oracle, then you want to shrink it as Oracle has its own buffer cache.
You could also mount file systems that you don't want buffer cache by:
-o mincache=direct
That will bypass the buffer cache all together - good option for Oracle on LVM.
What should you set it to?
Should be between 350MB to 800MB of ram - so you have to calculate the percent.
Rgds...Geoff
Proverbs 3:5,6 Trust in the Lord with all your heart and lean not on your own understanding; in all your ways acknowledge him, and he will make all your paths straight.
