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

Fri Dec 8 01:02:02 UTC 2006
MrKiwi <mrkiwi at gmail.com>

John R Pierce wrote:
> 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.
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Just out of curiosity John, are you allowed to give us some 
hints about what your system does? If you are posting on the 
CentOS list i presume you are running CentOS, rather than "a 
similar upstream product".
Also I'd love to know what you mean by "you do NOT want to 
have a single 10TB volume" - are you referring to 
performance or single-point-of-failure issues?