Re: Postgresql and uPortal

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Given, Robert A wrote:
| We are beginning to implement uPortal on Postgresql 7.4.8 on a
| z/Linux server. We are interested in obtaining information pertaining
| to any modification of the configuration parameters as distributed
| with the DBMS.
|
| Can anyone provide details on changes made such as:
|
| - adjustments in physical space allocation

What kind of storage are you using? Dedicated DASD or MDISKs, or perhaps
even SCSI? You may be able to achieve results ranging wildly on either
side of the scale, depending on your workload and storage scheme
deployed. Also, what kind of platform? LPAR or z/VM?

| - adjustments in virtual space allocation
| - shared buffers, cache sizes etc.
| - changes in database management parms

You will need to get a very good idea of what your average (database)
working set size is, because you're dealing with several layers of
indirection (IOCP cache, z/VM cache /if any/, z/Linux operating system
cache, page access frequencies) and it is extremely difficult to shoot
wild ducks and actually hit any in such an environment.

In general though, if you have a lot of guests on your machine, the rule
of thumb is, keep storage low, just a tiiiny bit higher than needed to
have the guest machine start paging, or even allow some (smaller) system
areas to be paged out, if it turns out they are seldomly used.

As for z/Linux parameters, PostgreSQL will ideally need page cache the
size of your working set.

| - changes in other system parms

Please specify more specific details on your current system environment.
You have not really given enough information to give any directly
related hints.

Regards,
- --
~ Grega Bremec
~ gregab at p0f dot net
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