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@xxxxxxxxxxxx> 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@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 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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>
>
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>
>
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>
>
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