[CentOS] Good value for /proc/sys/vm/min_free_kbytes

Fri Dec 8 00:50:04 UTC 2006
John R Pierce <pierce at hogranch.com>

Morten Torstensen wrote:
> John R Pierce wrote:
>> certainly are.    The database adminstrators will spend hours pouring 
>> over IO logs and database statistics in order to better optimize the 
>> distribution of tables and indicies across the available tablespaces.
> Didn't realise Oracle was that primitive. One should just balance all 
> the tablespaces out over multiple volumes and or controllers and add 
> table partitioning as needed. Transaction filesystem is a striped 
> filesystem over the same raid/volumes.
> Then if you need more I/O bandwidth you just add more controllers and 
> disks.

thats the shotgun approach, yes.  

in our case, our production systems are a very large very complex 
realtime oracle database running on large scale Sun enterprise hardware 
on bigiron EMC storage, using dozens and dozens of raid10 logical 
volumes as you do NOT want to have a single 10TB volume, sorry.   by 
hand optimizing the tablespace layouts of the applications tables and 
indicies, which have very specific access patterns, we can get double 
the throughput of the blind 'just stripe the universe' approach.   Since 
we're dealing with $millions worth of servers here at each production 
factory, tossing more iron at the problem isn't always the best 
solution.    btw, we've found Oracle 10's new 'self optimizer' to do a 
far worse job of query optimization than what we have been able to hand 
tune out of Oracle 9, so we're not upgrading until this changes.

we're embarking on a pilot project to evaluate a smaller scale version 
of this manufacturing execution system on linux + postgres as there are 
smaller installations which can't justify the costs of Oracle.