[CentOS] new memory not getting regonized

Sat Aug 27 19:12:45 UTC 2011

Dear Dennis,

Thanks a lot for the wise reply.. really did boost my knowledge..
honestly was unware of the fact that dom0 is just like another VM ...
Anyway I had never restricted dom0 mem and since my 4 vms were working fine  
with no issues
i never bothered much.

It was only after I added more 32 gb to existing 32 gb i did realise the  
above issue..

anyway I will try to restrict my dom0 to 1 GB ... and check it out.

but just still a litle confused why xm top & xm info shows 65gb
and top , free and cat /proc/meminfo shows 32 gb

apprecite your kind advice n help

Regards

simon

On Aug 27, 2011 3:44pm, Dennis Jacobfeuerborn <dennisml at conversis.de> wrote:
> 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 at 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:00000000:00000001

> >> 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 ie 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

> _______________________________________________

> CentOS mailing list

> CentOS at centos.org

> http://lists.centos.org/mailman/listinfo/centos

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.centos.org/pipermail/centos/attachments/20110827/9215aa4e/attachment.html>