PostgreSQL 8.4.3
Linux Redhat 5.0
Question: How much memory do I really need?
From my understanding there are two primary strategies for setting up PostgreSQL in relationship to memory:
1) Rely on Linux to cache the files. In this approach you set the shared_buffers to a relatively low number.
2) You can set shared_buffers to a very large percentage of your memory so that PostgreSQL reserves the memory for the database.
I am currently using option #1. I have 24 Gig of memory on my server and the database takes up 17 Gig of disk space. When I do the Linux command “top” I notice that 19 Gig is allocated for cache. Is there a way for me to tell how much of that cache is associated with the caching of database files?
I am basically asking how much memory do I really need? Maybe I have complete over kill. Maybe I am getting to a point where I might need more memory.
My thought was I could use option #2 and then set the number to a lower amount. If the performance is bad then slowly work the number up.
Our server manager seems to think that I have way to much memory. He thinks that we only need 5 Gig. I don’t really believe that. But I want to cover myself. With money tight I don’t want to be the person who is wasting resources. We need to replace our database servers so I want to do the right thing.
Thanks,
Lance Campbell
Software Architect/DBA/Project Manager
Web Services at Public Affairs
217-333-0382
