RE: We've Added more memory...but I can't remember!

[Evan Harris <spanner@xxxxxxxxxx>]

Charly

I always understood that stuff got paged out to disk because not everything
could remain in memory, therefore the more memory you had the less
(non-database ?)paging you would have. It seems from what you are saying
below that stuff is paged to disk anyway but this is contrary to what I had
understood to be the case.

I can understand jobs waiting on  disk for database accesses but in the
case you are describing (at least as far as I understand it)  I would have
thought more memory would help as it would have reduced the number of jobs
being paged out to disk. What am I missing here ?

BTW I'm quite enjoying the discussion regarding disk and performance so
feel free to continue with whatever length of explanation you can manage :)

Regards
Evan Harris

<SNIP>
>The question I was asked was: should we buy more memory or CPU?
>
>Welllll, some of the existing CPU is sitting idle, so more processors will
>not help.  They have 16 gigabytes of memory that is not very well utilized,
>so adding memory (without other changes) will probably provide little
>beneficial effect.
>
>The easiest (and least costly) thing they can do to improve performance is
>to find a way to reduce the non-database faulting.  The easiest pool to
>focus on would be *BASE.  The *BASE pool had 109 faults per second for 5
>minutes, or a little over 32,000 faults.  So 32,000 times in that five
>minutes something had to be brought into memory from the disks.
>
>With only 17 disk arms and the *BASE pool thrashing like it is, they
>probably aren't going to get good performance anytime soon.
>
>--  Charly
</SNIP>