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<DIV><SPAN class=038373220-21072005><FONT face=Arial color=#0000ff size=2>Here's
a snippet from some of my notes on PAE. Just remember that your hardware
must also support PAE.</FONT></SPAN></DIV>
<DIV><SPAN class=038373220-21072005><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=038373220-21072005>The 32bit architecture of the Intel x86 CPU
has a limit of 4GB of addressable memory. Servers which support Process Address
Extension (PAE) have a 36bit address space which supports up to 64GB of memory.
The <I class=EMPHASIS>RedHat 2.4.21 hugemem </I>kernel supports PAE in addition
to a memory model called the 4/4 split (64GB of memory and a ~4GB single memory
segment). </SPAN></DIV>
<DIV><SPAN class=038373220-21072005><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV></DIV>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left><FONT
face=Tahoma size=2>-----Original Message-----<BR><B>From:</B> Doerbeck,
Christoph <BR><B>Sent:</B> Thursday, July 21, 2005 4:21 PM<BR><B>To:</B> Red
Hat Network Users List<BR><B>Subject:</B> RE: [rhn-users] Unable to boot with
more than 4GB of RAM<BR><BR></FONT></DIV>
<DIV><SPAN class=087001420-21072005><FONT face=Arial color=#0000ff size=2>PAE
is a hardware/software trick that allows a 32bit system to address 36-bits of
memory (If I recall correctly). In any case, it technically allows up to
64 Gigs of ram. However, it's not linear and is broken into 3.2 (ish) gigabyte
pages of memory that can be addressed by a PAE enabled kernel.
Your hardware also has to support PAE (which I would think your box does? What
is your hardware?)</FONT></SPAN></DIV>
<DIV><SPAN class=087001420-21072005><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=087001420-21072005><FONT face=Arial color=#0000ff size=2>The
ELsmp kernel in RHEL3 is PAE enabled, but I think it only supports up to 16 GB
of ram (maybe it's 32).</FONT></SPAN></DIV>
<DIV><SPAN class=087001420-21072005><FONT face=Arial color=#0000ff
size=2>You'll need to install the ELhugemem kernel to go
higher.</FONT></SPAN></DIV>
<DIV><SPAN class=087001420-21072005><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=087001420-21072005><FONT face=Arial color=#0000ff size=2>Are
you sure you are running ELsmp? What does 'cat /proc/meminfo'
show?</FONT></SPAN></DIV>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV></DIV>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left><FONT
face=Tahoma size=2>-----Original Message-----<BR><B>From:</B>
Mei.Zhang@alltel.com [mailto:Mei.Zhang@alltel.com] <BR><B>Sent:</B>
Thursday, July 21, 2005 3:06 PM<BR><B>To:</B>
rhn-users@redhat.com<BR><B>Subject:</B> RE: [rhn-users] Unable to boot with
more than 4GB of RAM<BR><BR></FONT></DIV>
<DIV><SPAN class=335040419-21072005><FONT face=Arial color=#0000ff
size=2>You may need 64bit rhel</FONT></SPAN></DIV>
<P><FONT face="Lucida Console"><FONT size=2><SPAN
class=335040419-21072005>what is PAE enabled
kernel?</SPAN> </FONT></FONT> </P>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B>
rhn-users-bounces@redhat.com [mailto:rhn-users-bounces@redhat.com]<B>On
Behalf Of </B>Serge Bianda<BR><B>Sent:</B> Thursday, July 21, 2005 3:01
PM<BR><B>To:</B> rhn-users@redhat.com<BR><B>Subject:</B> [rhn-users]
Unable to boot with more than 4GB of RAM<BR><BR></FONT></DIV>
<DIV class=Section1>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Hello,<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">I had three machines that we
migrated from SuSE 9 to RHEL 3 ES, and Under SuSE the amount of memory was
showing correctly as 6GB, but under RHEL when I do a dmesg I get the
following report:<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"> Warning only 4GB will be
used.<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Use a <st1:stockticker
w:st="on">PAE</st1:stockticker> enabled
kernel.<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Any Ideay on how to resolve
that and have RHEL ustilize the maximum memory? I have the following
kernel loaded: 2.4.21-27.ELsmp<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><STRONG><B><FONT face=Tahoma color=#333333 size=1><SPAN
style="FONT-SIZE: 8.5pt; COLOR: #333333; FONT-FAMILY: Tahoma">Thanks<o:p></o:p></SPAN></FONT></B></STRONG></P>
<P class=MsoNormal><STRONG><B><FONT face=Tahoma color=#333333 size=1><SPAN
style="FONT-SIZE: 8.5pt; COLOR: #333333; FONT-FAMILY: Tahoma"><o:p> </o:p></SPAN></FONT></B></STRONG></P>
<P class=MsoNormal><STRONG><B><FONT face=Tahoma color=#333333 size=1><SPAN
style="FONT-SIZE: 8.5pt; COLOR: #333333; FONT-FAMILY: Tahoma">Serge</SPAN></FONT></B></STRONG><o:p></o:p></P>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><o:p> </o:p></SPAN></FONT></P></DIV></BLOCKQUOTE><PRE>******************************************************************************************
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