RE: [Xen-users] RHEL 5.2 Xen Kernel doesn't detect all amount of physical memory

[Ido Levy <IDOL@xxxxxxxxxx>]

Hi,

Thank you all for your replies.

The reason I brought up this issue is that currently I have a machine with
64GB RAM installed with RHEL 5.2 i386 version.
When using the PAE kernel the OS detects the total amount of memory, but
when using the Xen kernel that shipped with this Red Hat distribution it
detects only 14GB of RAM

I was wondering if I will install the x86_64 version of RHEL 5.2 will it
detects more memory.

Any help figure out what is the issue will be appreciated.
In addition I would be happy to provide the info to the guy from the Red
Hat support team.

Thanks

Ido



                                                                           
             "Robert Dunkley"                                              
             <Robert@xxxxxxxxx                                             
             >                                                          To 
             Sent by:                  <tom.ashley@xxxxxxxxx>              
             xen-users-bounces                                          cc 
             @lists.xensource.         Xen-users@xxxxxxxxxxxxxxxxxxx       
             com                                                   Subject 
                                       RE: [Xen-users] RHEL 5.2 Xen Kernel 
                                       doesn't detect all                  
             08/28/2008 02:24          amountofphysical memory             
             PM                                                            
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           




Hi,

I got a reply from RedHat support (Only emailed poster and not the list
initially). Max for RHEL Xen kernel is same as standard Kernel (1Tb for
X64) but max mem per VM is limited to 32Gb.

Reassuring to hear though, I was a bit worried that updating our Centos
5.2 systems from 32Gb Ram to 128Gb might not work :)


Rob

-----Original Message-----
From: tom.ashley@xxxxxxxxx [?mailto:tom.ashley@xxxxxxxxx]
Sent: 28 August 2008 12:15
To: Robert Dunkley; xen-users-bounces@xxxxxxxxxxxxxxxxxxx; Ido Levy
Cc: Xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] RHEL 5.2 Xen Kernel doesn't detect all
amountofphysical memory

Bog standard out of the box, I have a 64 bit centos 5.2 holding and
recognising 64GB RAM happily. RHEL should be able to do the same.
Sent using BlackBerry(r) from Orange

-----Original Message-----
From: "Robert Dunkley" <Robert@xxxxxxxxx>

Date: Thu, 28 Aug 2008 10:07:33
To: Ido Levy<IDOL@xxxxxxxxxx>
Cc: <Xen-users@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-users] RHEL 5.2 Xen Kernel doesn't detect all amount
             ofphysical memory


>From what I have read the XenServer distribution can support up to 32GB
RAM per VM and 128GB for the whole system.

My guess is that unless a deliberate restriction is put in place the
limits RAM for RHEL5 Xen kernel then 256Gb RAM in total and 32Gb RAM per
VM is probably the max.

Anyone know for sure?

-----Original Message-----
From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
[?mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Ido Levy
Sent: 28 August 2008 09:54
To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] RHEL 5.2 Xen Kernel doesn't detect all amount
ofphysical memory


Hello All,

Does anyone know what is the current status of RHEL 5.2 x86_64 with
respect
to the maximum amount of RAM detected by the Xen 64 bit kernel
(the one that shipped with Red Hat distribution )

In the following link
https://www.redhat.com/docs/manuals/enterprise/RHEL-5-manual/en-US/RHEL5
10/Virtualization_Guide/ch-virt-hw-support.html
it states that 32GB of RAM is the maximum amount of physical memory the
Xen
kernel can detect. Is it still the updated status ?

Is there a work around or any other way to overcome this limit ?

Any info would be appreciated

Thanks,

Ido


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