Regarding RAM replacement

 
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Operating Systems Linux Red Hat Regarding RAM replacement
# 1  
Old 09-09-2012
Regarding RAM replacement

Dear All,

I have linux Servers where all are having at present 12 Gig RAM.

At present my need is to increase the RAM for atleast another 12 G . ie 12G +12 G ===24 Gig RAM.

But how does i can find out whether my server will support for 24 GiG RAM or is there any way of finding out how much RAM ( Max ) can I put in the server...

any ideas pl let me know.


Rgds
Rj

---------- Post updated at 12:30 AM ---------- Previous update was at 12:29 AM ----------

pl find my server specifications

[oracle@development2 etc]$ cat redhat-release
Red Hat Enterprise Linux Server release 5.4 (Tikanga)
[oracle@development2 etc]$ uname -a
Linux development2 2.6.18-164.el5xen #1 SMP Tue Aug 18 16:06:30 EDT 2009 i686 i686 i386 GNU/Linux
[oracle@development2 etc]$
# 2  
Old 09-09-2012
I don't know well Red Hat, but here What are the Red Hat Enterprise Linux limits? — Bull On-line Support Portal you can read:
Quote:
RHEL-5 kernels:
i686 - no PAE, no hugemem patches, can address up to 4GB of memory
i686-PAE - PAE, no hugemem patches, can reliably run with around 16GB

So, in summary, if customers need to use > 16GB of memory, the absolute best suggestion is to use RHEL-5 x86_64, which suffers from none of these limitations.
I didn't find anything about a RHEL-5 i686 SMP kernel, but the RHEL-4 i686 SMP kernel is limited to 16GB too.

So at least be careful with your OS. With as little as 4GB RAM and up, a 64bit OS would be a wise choice.

If you're concerned with you hardware capabilities too, apart from reading your hardware manual you could try:
# dmidecode -t 16

Read man dmidecode for details.
--
Bye
# 3  
Old 09-10-2012
Dear Lem,

Thanks for the reply....

I have at present 5 servers for RAM expansion.

Out of which

4 servers are of RHEL 5.5/5.4---Tikanga ( 64 bit Version) SMP.
1 Server is RHEL 5.5-----Tikanga ( 32 bit Version ) SMP.

All the servers have 12 Gig now.

So how much maximum can i add in these servers.


Rgds Rj

---------- Post updated 09-10-12 at 12:09 AM ---------- Previous update was 09-09-12 at 10:48 PM ----------

I learnt that ..using pae we can extend the RAM allocated to 32 bit OS Linux ......But that will not cope up as the per process usage of RAM will be the same....And also better to add RAM in a 32 bit we can go for 64 bit....

But in my scenario ....i cant go for that option as every server is in to production and a lot of depedency pacakges of 32 bit...if converted to 64 bit ... so many packages i have to reinstall of 64 bit....

So is there any way that i can add RAM to this 32 bit version of RHEL 5.4

i686

Thanks and Regards
Rjj
# 4  
Old 09-10-2012
Quote:
Originally Posted by jegaraman
So how much maximum can i add in these servers.
Practically this is limited only by hardware restraints. The theoretical limit for a 64-bit-system is far higher than anything you can afford. (4GB is the limit for 32-bit addressing. Multiply this with 2^^32 again to get the limit of 64-bit addresses.)

The hardwares limit depends on which type of RAM you are using (this limits the size of the available RAM sticks) and the number of sockets on your board. Refer to your hardwares documentation for this info.


Quote:
But in my scenario ....i cant go for that option as every server is in to production and a lot of depedency pacakges of 32 bit...if converted to 64 bit ... so many packages i have to reinstall of 64 bit....
This (reinstallation with 64-bit) is probably the best solution anyway. A system with no possibility of a downtime is very poorly planned anyway and it will not hurt to redesign this setup now under controlled circumstances instead of in the case of hardware failure where the situation is unplanned.

If your managers or customers complain: let them. Don't care. What would they do if the hardware would break? If this would mean the end of the world, then how comes they haven't taken precautions against this when the system was planned?

Make it clear, that it is their own fault that the system was set up without any contingency. E-V-E-R-Y hardware has to be taken down / taken offline from time to time. For maintenance, for hardware upgrade, for whatever. That means that systems which must not go down, have to be designed as high-availability-clusters either with hot-standby-systems or something such or load-balancers and several identic machines behind that. If this is the case it is easy to take one system down, upgrade it, take over from the other system and take that down to upgrade it too.

Obviously this is not the case. There is no fallback system. Then your managers/customers have no business lamenting that such an upgrade takes time. Its their own fault. Don't have any compassion with them, they have been greedy bastards to save the extra costs and are now paying the price with the downtime.

You may want to do the reinstallation at a separate system and then only move the LUNs with the installed image to your server. This way you could do the upgrade faster and with less downtime. Anyway: the most important thing is to not let you hasten just because others need the system back urgently. If it would really be that urgent - see above. But by trying to do it faster than you comfortably can you run a high risk of doing something idiotic. This would be your fault - not succumbing to some managerial pressure is not.

So do what you have to do and take the times it takes to do it. If somebody has a problem with that - its his problem, not yours.

I hope this helps.

bakunin
# 5  
Old 09-11-2012
thanks for the detailed explanation bakunin
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