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@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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