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-   -   What is the difference between el5 and el5pae? (https://www.linuxquestions.org/questions/linux-newbie-8/what-is-the-difference-between-el5-and-el5pae-840562/)

struct 10-26-2010 11:54 AM
What is the difference between el5 and el5pae?
 
sometimes when I install Centos5 on separate machines, it boots with el5 kernel on one and other with el5PAE. Server models are almost identical to one another. such as identical motherboard, identical cpu, difference in Amount of RAM, different Harddrive manufacturer. I'm assuming this is hardware dependant but what is the difference between these two? I'm confused.

Expeto 10-26-2010 12:03 PM
Short version;
If you don't have more 4 gigs of ram, you don't need a PAE kernel. Its not a efficiency or being lightweight thing. Non PAE kernel cannot allocate more than 4gigs.

Long version:
http://en.wikipedia.org/wiki/Physical_Address_Extension

struct 10-26-2010 12:12 PM
Ohhhhhh.... Thx Expeto. now I see why.
I installed fresh on a hardware with 4GB of RAM and it gave me el5PAE.
I do have a question now that I know what's up. :D
I got three systems total. One I just installed fresh with centos5 that gave me el5PAE. And two other systems which had installed OS but later upgraded RAM but only shows el5. How do I change this so it will boot with PAE mode? Any pointers?

fbobraga 10-26-2010 12:17 PM
Quote:
Originally Posted by struct (Post 4139943)
How do I change this so it will boot with PAE mode? Any pointers?
I think will only need to install the kernel-PAE package
Code:
# yum install kernel-PAE

struct 10-26-2010 12:55 PM
Quote:
Originally Posted by fbobraga (Post 4139951)
I think will only need to install the kernel-PAE package
Code:
# yum install kernel-PAE
Cool Thank you. It worked.

carlosinfl 10-26-2010 01:49 PM
The PAE kernel is obviously irrelevant in all 64-bit systems running a true 64-bit kernel. I remember using a PAE in CentOS back when we had 32-bit servers.


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