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 <denni...@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@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
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