I had a Centos 5.5 OS running for about 6 months used as a Xen VM server prfectly running 3 Virtual machines
Its a Sun Blade server with 8 core Xeon Proceesor with 32 GB Ram
couple of days back I added another 32 gb ram .
The bios shows the added ram that is now it shows me 64 GB but the Centos OS just recognizes 32gb only
the OS details are:
Centos release 5.5 final
Kernel 2.6.18-194.32.1.el5xen on an x86_64
now also running uname -a shows me
Linux hypervisor2 2.6.18-194.32.1.el5xen #1 SMP Wed Jan 5 18:44:24 EST 2011 x86_64 x86_64 x86_64 GNU/Linux
shows that PAE support is not there
I do believe that installing kernel PAE with yum should solve the problem but since the server is a online production server just wanted to verify if I would run into some problems
apprecite your kinf help and suggestions
regards
sylvan____________________________________________ ___
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08-26-2011, 10:23 AM
Leonard den Ottolander
new memory not getting regonized
Hello Sylvan,
On Fri, 2011-08-26 at 10:10 +0000, sylvan.dcunha@gmail.com wrote:
> Kernel 2.6.18-194.32.1.el5xen on an x86_64
> I do believe that installing kernel PAE with yum should solve the
> problem but since the server is a online production server just wanted
> to verify if I would run into some problems
I have no idea why your server doesn't see the extra 32GB, but you do
*not* need a PAE kernel. PAE is a hack for 32bit system to use more than
4GB of memory. Your machine is a 64bit system, so you don't need a PAE
kernel on it.
Regards,
Leonard.
--
mount -t life -o ro /dev/dna /genetic/research
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08-26-2011, 10:51 AM
benedict dcunha
new memory not getting regonized
Thanks Leonard,
*
Thanks for the immedite reply . apprecite.
actually many post s say the PAE kernel required for addressing more than 4 gb ram . but since my server already detects 32 gb ram , detecting 64 also should not be an issue..
*
but just wondering why??.
*
*
*
regards
*
simon
*
On Fri, Aug 26, 2011 at 1:23 PM, Leonard den Ottolander <leonard@den.ottolander.nl> wrote:
Hello Sylvan,
On Fri, 2011-08-26 at 10:10 +0000, sylvan.dcunha@gmail.com wrote:
> Kernel 2.6.18-194.32.1.el5xen on an x86_64
> I do believe that installing kernel PAE with yum should solve the
> problem but since the server is a online production server just wanted
> to verify if I would run into some problems
I have no idea why your server doesn't see the extra 32GB, but you do
*not* need a PAE kernel. PAE is a hack for 32bit system to use more than
4GB of memory. Your machine is a 64bit system, so you don't need a PAE
kernel on it.
Regards,
Leonard.
--
mount -t life -o ro /dev/dna /genetic/research
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08-26-2011, 12:29 PM
Dennis Jacobfeuerborn
new memory not getting regonized
On 08/26/2011 12:51 PM, benedict dcunha wrote:
> Thanks Leonard,
> Thanks for the immedite reply . apprecite.
> actually many post s say the PAE kernel required for addressing more than 4
> gb ram . but since my server already detects 32 gb ram , detecting 64 also
> should not be an issue..
"many posts say" a lot of things. Either these posts are specifically
talking about 32bit systems or they are wrong.
With a 32bit integer you can only address 4gb of ram so a hack was devised
to make it possible go beyond that limit called PAE.
Since with 64bit you no longer have that problem PAE doesn't exist on a
64bit system.
No idea but it has nothing to do with PAE. Can you post the output of "xm
info"?
Regards,
Dennis
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08-26-2011, 12:29 PM
Dennis Jacobfeuerborn
new memory not getting regonized
On 08/26/2011 12:51 PM, benedict dcunha wrote:
> Thanks Leonard,
> Thanks for the immedite reply . apprecite.
> actually many post s say the PAE kernel required for addressing more than 4
> gb ram . but since my server already detects 32 gb ram , detecting 64 also
> should not be an issue..
"many posts say" a lot of things. Either these posts are specifically
talking about 32bit systems or they are wrong.
With a 32bit integer you can only address 4gb of ram so a hack was devised
to make it possible go beyond that limit called PAE.
Since with 64bit you no longer have that problem PAE doesn't exist on a
64bit system.
No idea but it has nothing to do with PAE. Can you post the output of "xm
info"?
Regards,
Dennis
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08-26-2011, 12:34 PM
John Doe
new memory not getting regonized
From: "sylvan.dcunha@gmail.com" <sylvan.dcunha@gmail.com>
>I had a Centos 5.5 OS**running for about 6 months used as a Xen VM server prfectly running 3 Virtual machines
>Its a Sun Blade server with 8 core Xeon Proceesor with 32 GB Ram
>couple of days back I added another 32 gb ram .
>The bios shows the added ram that is now it shows me 64 GB but the Centos OS just recognizes 32gb only
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08-26-2011, 12:34 PM
John Doe
new memory not getting regonized
From: "sylvan.dcunha@gmail.com" <sylvan.dcunha@gmail.com>
>I had a Centos 5.5 OS**running for about 6 months used as a Xen VM server prfectly running 3 Virtual machines
>Its a Sun Blade server with 8 core Xeon Proceesor with 32 GB Ram
>couple of days back I added another 32 gb ram .
>The bios shows the added ram that is now it shows me 64 GB but the Centos OS just recognizes 32gb only
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08-27-2011, 11:22 AM
benedict dcunha
new memory not getting regonized
Thanks Guys
*
really apprecite your quick responses.
( Dennis was right in tellin me about PAE since my system is 64 bit and if I do run yum install kernel-PAE there is nothing found.)
*
actually i found something more as i was figuring my issue out.
*
when I do a* top i see the following
---------------
*
Tasks: 285 total,** 1 running, 284 sleeping,** 0 stopped,** 0 zombie
Cpu(s):* 0.0%us,* 0.0%sy,* 0.0%ni, 99.8%id,* 0.2%wa,* 0.0%hi,* 0.0%si,* 0.0%st
Mem:* 33554432k total, 15430836k used, 18123596k free,** 323176k buffers
Swap:* 2819396k total,******* 0k used,* 2819396k free, 13860960k cached
* PID USER***** PR* NI* VIRT* RES* SHR S %CPU %MEM*** TIME+* COMMAND
---------------
*
when I run cat /proc/meminfo i see
*
----MemTotal:**** 33554432 kB
MemFree:***** 18123588 kB
Buffers:******* 323192 kB
Cached:****** 13860992 kB
SwapCached:********* 0 kB
Active:******* 9601264 kB
Inactive:***** 4643904 kB
HighTotal:********** 0 kB
VmallocUsed:***** 3304 kB
VmallocChunk: 34359733919 kB
------------
*
actually I had run the above 2 command and found the memory was 32gb
but as dennis said when I run the command
xm info
----------------------
[root@hypervisor2 ~]# xm info
host****************** : hypervisor2
release*************** : 2.6.18-194.32.1.el5xen
version*************** : #1 SMP Wed Jan 5 18:44:24 EST 2011
machine*************** : x86_64
* 0*** 0
*** zimbra --b---***** 26183*** 7.8*** 2105220*** 3.1*** 4210688****** 6.3**** 4*** 1******* 0****** 16*** 1******* 0******* 0
* 0*** 0
----------------------
*
so the above 2 command show me 64gb
*
Now I m confused ..
*
Is my Centos XEN server actually using the 64 bit ...
and which command actually show me the right memory status
*
*
apprecite once again and thnaks
*
regards
*
sylvan
*
*
*
*
*
*
*
*
*
*
On Fri, Aug 26, 2011 at 3:29 PM, Dennis Jacobfeuerborn <dennisml@conversis.de> wrote:
On 08/26/2011 12:51 PM, benedict dcunha wrote:
> Thanks Leonard,
> Thanks for the immedite reply . apprecite.
> actually many post s say the PAE kernel required for addressing more than 4
> gb ram . but since my server already detects 32 gb ram , detecting 64 also
> should not be an issue..
"many posts say" a lot of things. Either these posts are specifically
talking about 32bit systems or they are wrong.
With a 32bit integer you can only address 4gb of ram so a hack was devised
to make it possible go beyond that limit called PAE.
Since with 64bit you no longer have that problem PAE doesn't exist on a
64bit system.
No idea but it has nothing to do with PAE. Can you post the output of "xm
info"?
Regards,
* Dennis
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08-27-2011, 12:35 PM
"Simon Matter"
new memory not getting regonized
> Thanks Guys
>
> really apprecite your quick responses.
> ( Dennis was right in tellin me about PAE since my system is 64 bit and if
> I
> do run yum install kernel-PAE there is nothing found.)
>
> actually i found something more as i was figuring my issue out.
>
> when I do a top i see the following
> ---------------
>
> Tasks: 285 total, 1 running, 284 sleeping, 0 stopped, 0 zombie
> Cpu(s): 0.0%us, 0.0%sy, 0.0%ni, 99.8%id, 0.2%wa, 0.0%hi, 0.0%si,
> 0.0%st
> Mem: 33554432k total, 15430836k used, 18123596k free, 323176k buffers
> Swap: 2819396k total, 0k used, 2819396k free, 13860960k cached
> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
> ---------------
>
> when I run cat /proc/meminfo i see
>
> ----MemTotal: 33554432 kB
> MemFree: 18123588 kB
> Buffers: 323192 kB
> Cached: 13860992 kB
> SwapCached: 0 kB
> Active: 9601264 kB
> Inactive: 4643904 kB
> HighTotal: 0 kB
> HighFree: 0 kB
> LowTotal: 33554432 kB
> LowFree: 18123588 kB
> SwapTotal: 2819396 kB
> SwapFree: 2819396 kB
> Dirty: 8 kB
> Writeback: 0 kB
> AnonPages: 60972 kB
> Mapped: 12528 kB
> Slab: 360860 kB
> PageTables: 18444 kB
> NFS_Unstable: 0 kB
> Bounce: 0 kB
> CommitLimit: 19596612 kB
> Committed_AS: 394740 kB
> VmallocTotal: 34359738367 kB
> VmallocUsed: 3304 kB
> VmallocChunk: 34359733919 kB
> ------------
>
> actually I had run the above 2 command and found the memory was 32gb
> but as dennis said when I run the command
> xm info
> ----------------------
> [root@hypervisor2 ~]# xm info
> host : hypervisor2
> release : 2.6.18-194.32.1.el5xen
> version : #1 SMP Wed Jan 5 18:44:24 EST 2011
> machine : x86_64
> nr_cpus : 16
> nr_nodes : 1
> sockets_per_node : 2
> cores_per_socket : 4
> threads_per_core : 2
> cpu_mhz : 2527
> hw_caps :
> bfebfbff:28100800:00000000:00000140:009ce3bd:00000 000:00000001
> total_memory : 65527
> free_memory : 22989
> node_to_cpu : node0:0-15
> xen_major : 3
> xen_minor : 1
> xen_extra : .2-194.32.1.el5
> xen_caps : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32
> hvm-3.0-x86_32p hvm-3.0-x86_64
> xen_pagesize : 4096
> platform_params : virt_start=0xffff800000000000
> xen_changeset : unavailable
> cc_compiler : gcc version 4.1.2 20080704 (Red Hat 4.1.2-48)
> cc_compile_by : mockbuild
> cc_compile_domain : centos.org
> cc_compile_date : Wed Jan 5 17:43:03 EST 2011
> xend_config_format : 2
> --------------------
> and then I ran xm top i see
>
> -------------
>
> 5 domains: 1 running, 4 blocked, 0 paused, 0 crashed, 0 dying, 0 shutdown
> Mem: 67099744k total, 43558844k used, 23540900k free CPUs: 16 @ 2527MHz
> NAME STATE CPU(sec) CPU(%) MEM(k) MEM(%) MAXMEM(k) MAXMEM(%)
> VCPUS NETS NETTX(k) NETRX(k) VBDS VBD_OO VBD_RD VBD
> _WR SSID
> Domain-0 -----r 8401 2.4 33554688 50.0 no limit
> n/a 16 4 1892 16848120 0 0 0
> 0 0
> sepmback --b--- 9758 2.6 2105220 3.1 4210688
> 6.3 4 1 0 0 1 0 0
> 0 0
> winserver2 --b--- 5758 0.9 1056644 1.6 4210688
> 6.3 1 1 0 0 1 0 0
> 0 0
> wsusserver --b--- 25812 11.4 3256196 4.9 8404992
> 12.5 4 1 0 0 1 0 0
> 0 0
> zimbra --b--- 26183 7.8 2105220 3.1 4210688
> 6.3 4 1 0 16 1 0 0
> 0 0
> ----------------------
>
> so the above 2 command show me 64gb
>
> Now I m confused ..
>
> Is my Centos XEN server actually using the 64 bit ...
> and which command actually show me the right memory status
I'm not sure but I think everything is okay with your box. "xm top" shows
that your box run with 64Gb memory, and what "top" shows is that your Dom0
OS runs with 32Gb memory, which means your DomU's take the other 32Gb. Did
you up the memory settings in your virtual hosts configuration? After
doing so you should see the Dom0 memory to go down when looking at it with
"top".
Regards,
Simon
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08-27-2011, 12:44 PM
Dennis Jacobfeuerborn
new memory not getting regonized
On 08/27/2011 02:35 PM, Simon Matter wrote:
>> Thanks Guys
>>
>> really apprecite your quick responses.
>> ( Dennis was right in tellin me about PAE since my system is 64 bit and if
>> I
>> do run yum install kernel-PAE there is nothing found.)
>>
>> actually i found something more as i was figuring my issue out.
>>
>> when I do a top i see the following
>> ---------------
>>
>> Tasks: 285 total, 1 running, 284 sleeping, 0 stopped, 0 zombie
>> Cpu(s): 0.0%us, 0.0%sy, 0.0%ni, 99.8%id, 0.2%wa, 0.0%hi, 0.0%si,
>> 0.0%st
>> Mem: 33554432k total, 15430836k used, 18123596k free, 323176k buffers
>> Swap: 2819396k total, 0k used, 2819396k free, 13860960k cached
>> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
>> ---------------
>>
>> when I run cat /proc/meminfo i see
>>
>> ----MemTotal: 33554432 kB
>> MemFree: 18123588 kB
>> Buffers: 323192 kB
>> Cached: 13860992 kB
>> SwapCached: 0 kB
>> Active: 9601264 kB
>> Inactive: 4643904 kB
>> HighTotal: 0 kB
>> HighFree: 0 kB
>> LowTotal: 33554432 kB
>> LowFree: 18123588 kB
>> SwapTotal: 2819396 kB
>> SwapFree: 2819396 kB
>> Dirty: 8 kB
>> Writeback: 0 kB
>> AnonPages: 60972 kB
>> Mapped: 12528 kB
>> Slab: 360860 kB
>> PageTables: 18444 kB
>> NFS_Unstable: 0 kB
>> Bounce: 0 kB
>> CommitLimit: 19596612 kB
>> Committed_AS: 394740 kB
>> VmallocTotal: 34359738367 kB
>> VmallocUsed: 3304 kB
>> VmallocChunk: 34359733919 kB
>> ------------
>>
>> actually I had run the above 2 command and found the memory was 32gb
>> but as dennis said when I run the command
>> xm info
>> ----------------------
>> [root@hypervisor2 ~]# xm info
>> host : hypervisor2
>> release : 2.6.18-194.32.1.el5xen
>> version : #1 SMP Wed Jan 5 18:44:24 EST 2011
>> machine : x86_64
>> nr_cpus : 16
>> nr_nodes : 1
>> sockets_per_node : 2
>> cores_per_socket : 4
>> threads_per_core : 2
>> cpu_mhz : 2527
>> hw_caps :
>> bfebfbff:28100800:00000000:00000140:009ce3bd:00000 000:00000001
>> total_memory : 65527
>> free_memory : 22989
>> node_to_cpu : node0:0-15
>> xen_major : 3
>> xen_minor : 1
>> xen_extra : .2-194.32.1.el5
>> xen_caps : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32
>> hvm-3.0-x86_32p hvm-3.0-x86_64
>> xen_pagesize : 4096
>> platform_params : virt_start=0xffff800000000000
>> xen_changeset : unavailable
>> cc_compiler : gcc version 4.1.2 20080704 (Red Hat 4.1.2-48)
>> cc_compile_by : mockbuild
>> cc_compile_domain : centos.org
>> cc_compile_date : Wed Jan 5 17:43:03 EST 2011
>> xend_config_format : 2
>> --------------------
>> and then I ran xm top i see
>>
>> -------------
>>
>> 5 domains: 1 running, 4 blocked, 0 paused, 0 crashed, 0 dying, 0 shutdown
>> Mem: 67099744k total, 43558844k used, 23540900k free CPUs: 16 @ 2527MHz
>> NAME STATE CPU(sec) CPU(%) MEM(k) MEM(%) MAXMEM(k) MAXMEM(%)
>> VCPUS NETS NETTX(k) NETRX(k) VBDS VBD_OO VBD_RD VBD
>> _WR SSID
>> Domain-0 -----r 8401 2.4 33554688 50.0 no limit
>> n/a 16 4 1892 16848120 0 0 0
>> 0 0
>> sepmback --b--- 9758 2.6 2105220 3.1 4210688
>> 6.3 4 1 0 0 1 0 0
>> 0 0
>> winserver2 --b--- 5758 0.9 1056644 1.6 4210688
>> 6.3 1 1 0 0 1 0 0
>> 0 0
>> wsusserver --b--- 25812 11.4 3256196 4.9 8404992
>> 12.5 4 1 0 0 1 0 0
>> 0 0
>> zimbra --b--- 26183 7.8 2105220 3.1 4210688
>> 6.3 4 1 0 16 1 0 0
>> 0 0
>> ----------------------
>>
>> so the above 2 command show me 64gb
>>
>> Now I m confused ..
>>
>> Is my Centos XEN server actually using the 64 bit ...
>> and which command actually show me the right memory status
>
> I'm not sure but I think everything is okay with your box. "xm top" shows
> that your box run with 64Gb memory, and what "top" shows is that your Dom0
> OS runs with 32Gb memory, which means your DomU's take the other 32Gb. Did
> you up the memory settings in your virtual hosts configuration? After
> doing so you should see the Dom0 memory to go down when looking at it with
> "top".
Benedict is right. Remember that under Xen Dom0 is really just another VM
with special privileges. In fact on all my host systems I restrict Dom0 to
1G of ram by adding a "dom0_mem=1024M" argument to the grub configuration.
In practice Xen should reduce the amount of ram used by Dom0 dynamically as
needed for VMs i.e. if your virtual machines use 48G of ram then dom0
should only show 16G left. A while ago this mechanism lead to instability
though so a general recommendation was to set dom0 memory to a fixed 1G or
512M to not rely on this dynamic memory handling.
Check this out for example:
http://lists.xensource.com/archives/html/xen-users/2008-06/msg00729.html
Regards,
Dennis
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new memory not getting regonized
