[CentOS] CENTOS 4.7 or 5.2 32 bits O.S. for ORACLE DB server??

Warren Young warren at etr-usa.com
Fri Jan 16 16:28:01 UTC 2009


mcclnx mcc wrote:
> we plan to setup our ORACLE database server (32 bits DB) and use dell
> r900 server.  This server can put up to 128GB RAM.
> 
> We are thinking use 32 bits CENTOS 4.7 or 5.2.  My concern about
> CENTOS 5.2 is it only support up to 16 GB RAM on 32 bits O.S.
> 
> Any suggestion?

To get beyond 4 GB of RAM with a 32-bit Intel CPU, you have to turn on
PAE mode, which is a very ugly hack, invented several years ago now.  It
dates back to the old Pentium Pro!  It was created before inexpensive
64-bit CPUs were available.  Systems being built today should not use
PAE mode, IMHO.  If you need more than 4 GB of RAM today, use a 64-bit
OS and applications.  That will let you address the full memory
capability of that server.

In PAE mode, the system runs a little slower due to the extra overhead
of the more complicated memory management scheme, and it can't really
address that 16 GB all at once.  It's kind of a like the old DOS days
when we had 32-bit CPUs but could only address 64 KB of memory at a
time, and could only access 640 KB without resorting to PAE-like hacks
called EMS and XMS.  These workarounds are best consigned to the dustbin
of history.


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