On Wed, Apr 28, 2010 at 7:08 PM, Jaime Rodriguez <jaime.rodrig...@liberux.com> wrote: > hi, > Today is my first day looking at PostgreSQL > I am looking to migrate a MS SQL DB to PostgreSQL :) :) > My customer requires that DBMS shall support 4000 simultaneous requests > Also the system to be deploy maybe a cluster, with 12 microprocessors
I'm gonna jump in here and say that if you 400 REQUESTS running at the same time, you're gonna want a REALLY big machine. I admin a setup where two db servers handle ~200 simultaneous requests, almost all being very short millisecond long requests, and a few being 100 milliseconds, and a very very few running for seconds. With 8 2.1 GHz Opteron cores, 32 Gigs of ram, and 14x15k drives those machines run with a load factor in the range of 10 to 15. CPUs are maxed at that range of load, and IO is 70 to 80% utilized acording to iostat -x. Wait % is generally one core max. Some of that load is fixed on the master, but a lot can be handled by slaves. Your load, if you really are having 4000 simultaneous connections, is likely going to need 20 times the load handling I need. Given the newer 12 core AMDs are somewhat faster, you could probably get away with two or three of these machines. If you were to use 96 core machines (8Px12core) with as many disks as you could throw at them (40 to 100) then you're in the ballpark for a set of machines to process 4,000 simultaneous requests, assuming a mostly read (80% or so) setup. We're talking a large % of a full sized rack to hold all the drives and cores you'd need. But this brings up a lot of questions about partitioning your dataset if you can, things like that. Do all of these 4,000 simultaneous requests need to update the same exact data set? Or are they read mostly reporting users? Can you use memcached to handle part of the load? Usage patterns informs a great deal on how to size a system to handle that much load. -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
