RE: 32 bit and 64 bit memory

Lyndon - How about "more memory than you can afford". On most Unix systems, and I assume Linux is roughly similar, there is a kernel setting that is effectively the "per process limit". If you have 4 gig real memory, you would set the per process limit much lower because all processes must share that total real memory. On a server you don't dare set this too high or you get to learn about "swapping" and how much swap space you must allocate for swapping. Like Oracle, set something really wild and you can get some fireworks.

Dennis Williams
DBA, 40%OCP, 100% DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com

-----Original Message-----
Sent: Friday, February 28, 2003 3:24 PM
To: Multiple recipients of list ORACLE-L

That 3g limit only applies to Windows (2g w/o the boot.ini /3g switch). Linux is a whole other bowl of wax. Having never run Oracle in Linux I'm afraid I can't answer your question. My best guess would be the per process limit is 4g, but on most unix platforms the SGA (which the OP was about) is outside of the session processes. It's a chunk of shared memory. I don't know what limits Linux places on shared memory segments.

• Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Friday, February 28, 2003 3:23 PM

> Hey, I just remembered that Oracle on Linux runs as multiple processes
> , unlike Oracle on Windows which runs as one big process. Does this
> mean each Oracle process on Linux can access 3GB of memory? So that in
> the end the whole of Oracle can actually use greater than 3GB of memory?
>
> --
> Lyndon Tiu
>
>
> Quoting Chuck Hamilton <chuckh_at_softhome.net>:
>
> > By default, Windows imposes a 2g per process limit on all
> > processes
> > including the OS itself. Oracle runs as a process with each session
> > running
> > as a thread within that process so the entire Oracle process
> > including SGA,
> > sessions, DLLs, executables, etc. must all fit within 2g. There is
> > a
> > boot.ini switch that raises the limit to 3g while reducing the
> > OS's
> > addressable memory to 1g.
> >
> > I can't speak to other 32 or 64 bit platforms from experience as
> > I've never
> > tried to push any of them to the limit.You need to remember though
> > that
> > X-bit processor doesn't necessarily mean X-bit addressability.
> > Unless I'm
> > mistaken the bit size of a processor represents the size of the
> > registers,
> > instructions and internal busses, but not the memory addressability
> > which is
> > limited by other things in the hardware. Having said that, current
> > 32 bit
> > platforms can usually addresses 4g.
> > --
> > Chuck
> >
> > ----- Original Message -----
> > To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
> > Sent: Friday, February 28, 2003 12:34 PM
> >
> >
> > > Hello,
> > >
> > > 1) How big (max) can an Oracle SGA be in a 32bit platform
> > (Windows and
> > > Linux on ia32)?
> > >
> > > 2) How big (max) can an Oracle SGA be on a 64bit platform
> > (Sparc
> > > Solaris, AIX PowerPC)?
> > >
> > > Thanks.
> > >
> > > --
> > > Lyndon Tiu
> > >
> > >
> > >
> > >
> > >
> > > --
> > > Please see the official ORACLE-L FAQ: http://www.orafaq.net
> > > --
> > > Author: Lyndon Tiu
> > > INET: ltiu_at_alumni.sfu.ca
> > >
> > > Fat City Network Services -- 858-538-5051
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> > --
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> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> Author: Lyndon Tiu
> INET: ltiu_at_alumni.sfu.ca
>
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-- 
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-- 
Author: Chuck Hamilton
  INET: chuckh_at_softhome.net

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-- 
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-- 
Author: DENNIS WILLIAMS
  INET: DWILLIAMS_at_LIFETOUCH.COM

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