Re: Seeking performance advice and explanation for high I/O on 8.3

Claus Guttesen kometen(at)gmail(dot)com:

> > Would love to get some advice on how to change my conf settings / setup to
> > get better I/O performance.
> >
> > Server Specs:
> >
> > 2x Intel Xeon Quad Core (@2 Ghz - Clovertown,L5335)
> > 4GB RAM
> > 4x Seagate 73GB SAS HDD 10k RPM - in RAID ( stripped and mirrored )
> >
> > FreeBSD 6.4
> > Apache 2.2
> > PostgreSQL 8.3.6
> > PHP 5.2.9
> >
> > ~1500 databases w/ ~60 tables each
> >
> > max_connections = 600
> > shared_buffers = 1GB

> On a dual-core HP DL380 with 16 GB ram I have set shared_buffers at
> 512 MB for 900 max_connections. Far the largest table have approx. 120
> mill. records. You could try to lower shared_buffers.

> > max_fsm_pages = 2800000
> > max_fsm_relations = 160000

> What does the last couple of lines from a 'vacuum analyze verbose'
> say? I have max_fsm_pages = 4000000 and max_fsm_relations = 1500.

> You can also try to lower random_page_cost to a lower value like 1.2
> but I doubt this will help in your case.

last couple lines from 'vacuumdb -a -v -z':

INFO: free space map contains 114754 pages in 42148 relations
DETAIL: A total of 734736 page slots are in use (including overhead).
734736 page slots are required to track all free space.
Current limits are: 2800000 page slots, 160000 relations, using 26810 kB.

Scott