Dear Dennis,
<br />
<br />Thanks a lot for the wise reply.. really did boost my knowledge..
<br />honestly was unware of the fact that dom0 is just like another VM ...
<br />Anyway I had never restricted dom0 mem and since my 4 vms were working fine with no issues
<br />i never bothered much.
<br />
<br />It was only after I added more 32 gb to existing 32 gb i did realise the above issue..
<br />
<br />anyway I will try to restrict my dom0 to 1 GB ... and check it out.
<br />
<br />but just still a litle confused why xm top & xm info shows 65gb
<br />and top , free and cat /proc/meminfo shows 32 gb
<br />
<br />apprecite your kind advice n help
<br />
<br />
<br />Regards
<br />
<br />simon
<br />
<br />
<br />On Aug 27, 2011 3:44pm, Dennis Jacobfeuerborn <dennisml@conversis.de> wrote:
<br />> On 08/27/2011 02:35 PM, Simon Matter wrote:
<br />>
<br />>
<br />> >> Thanks Guys
<br />>
<br />>
<br />> >>
<br />>
<br />>
<br />> >> really apprecite your quick responses.
<br />>
<br />>
<br />> >> ( Dennis was right in tellin me about PAE since my system is 64 bit and if
<br />>
<br />>
<br />> >> I
<br />>
<br />>
<br />> >> do run yum install kernel-PAE there is nothing found.)
<br />>
<br />>
<br />> >>
<br />>
<br />>
<br />> >> actually i found something more as i was figuring my issue out.
<br />>
<br />>
<br />> >>
<br />>
<br />>
<br />> >> when I do a top i see the following
<br />>
<br />>
<br />> >> ---------------
<br />>
<br />>
<br />> >>
<br />>
<br />>
<br />> >> Tasks: 285 total, 1 running, 284 sleeping, 0 stopped, 0 zombie
<br />>
<br />>
<br />> >> Cpu(s): 0.0%us, 0.0%sy, 0.0%ni, 99.8%id, 0.2%wa, 0.0%hi, 0.0%si,
<br />>
<br />>
<br />> >> 0.0%st
<br />>
<br />>
<br />> >> Mem: 33554432k total, 15430836k used, 18123596k free, 323176k buffers
<br />>
<br />>
<br />> >> Swap: 2819396k total, 0k used, 2819396k free, 13860960k cached
<br />>
<br />>
<br />> >> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
<br />>
<br />>
<br />> >> ---------------
<br />>
<br />>
<br />> >>
<br />>
<br />>
<br />> >> when I run cat /proc/meminfo i see
<br />>
<br />>
<br />> >>
<br />>
<br />>
<br />> >> ----MemTotal: 33554432 kB
<br />>
<br />>
<br />> >> MemFree: 18123588 kB
<br />>
<br />>
<br />> >> Buffers: 323192 kB
<br />>
<br />>
<br />> >> Cached: 13860992 kB
<br />>
<br />>
<br />> >> SwapCached: 0 kB
<br />>
<br />>
<br />> >> Active: 9601264 kB
<br />>
<br />>
<br />> >> Inactive: 4643904 kB
<br />>
<br />>
<br />> >> HighTotal: 0 kB
<br />>
<br />>
<br />> >> HighFree: 0 kB
<br />>
<br />>
<br />> >> LowTotal: 33554432 kB
<br />>
<br />>
<br />> >> LowFree: 18123588 kB
<br />>
<br />>
<br />> >> SwapTotal: 2819396 kB
<br />>
<br />>
<br />> >> SwapFree: 2819396 kB
<br />>
<br />>
<br />> >> Dirty: 8 kB
<br />>
<br />>
<br />> >> Writeback: 0 kB
<br />>
<br />>
<br />> >> AnonPages: 60972 kB
<br />>
<br />>
<br />> >> Mapped: 12528 kB
<br />>
<br />>
<br />> >> Slab: 360860 kB
<br />>
<br />>
<br />> >> PageTables: 18444 kB
<br />>
<br />>
<br />> >> NFS_Unstable: 0 kB
<br />>
<br />>
<br />> >> Bounce: 0 kB
<br />>
<br />>
<br />> >> CommitLimit: 19596612 kB
<br />>
<br />>
<br />> >> Committed_AS: 394740 kB
<br />>
<br />>
<br />> >> VmallocTotal: 34359738367 kB
<br />>
<br />>
<br />> >> VmallocUsed: 3304 kB
<br />>
<br />>
<br />> >> VmallocChunk: 34359733919 kB
<br />>
<br />>
<br />> >> ------------
<br />>
<br />>
<br />> >>
<br />>
<br />>
<br />> >> actually I had run the above 2 command and found the memory was 32gb
<br />>
<br />>
<br />> >> but as dennis said when I run the command
<br />>
<br />>
<br />> >> xm info
<br />>
<br />>
<br />> >> ----------------------
<br />>
<br />>
<br />> >> [root@hypervisor2 ~]# xm info
<br />>
<br />>
<br />> >> host : hypervisor2
<br />>
<br />>
<br />> >> release : 2.6.18-194.32.1.el5xen
<br />>
<br />>
<br />> >> version : #1 SMP Wed Jan 5 18:44:24 EST 2011
<br />>
<br />>
<br />> >> machine : x86_64
<br />>
<br />>
<br />> >> nr_cpus : 16
<br />>
<br />>
<br />> >> nr_nodes : 1
<br />>
<br />>
<br />> >> sockets_per_node : 2
<br />>
<br />>
<br />> >> cores_per_socket : 4
<br />>
<br />>
<br />> >> threads_per_core : 2
<br />>
<br />>
<br />> >> cpu_mhz : 2527
<br />>
<br />>
<br />> >> hw_caps :
<br />>
<br />>
<br />> >> bfebfbff:28100800:00000000:00000140:009ce3bd:00000000:00000001
<br />>
<br />>
<br />> >> total_memory : 65527
<br />>
<br />>
<br />> >> free_memory : 22989
<br />>
<br />>
<br />> >> node_to_cpu : node0:0-15
<br />>
<br />>
<br />> >> xen_major : 3
<br />>
<br />>
<br />> >> xen_minor : 1
<br />>
<br />>
<br />> >> xen_extra : .2-194.32.1.el5
<br />>
<br />>
<br />> >> xen_caps : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32
<br />>
<br />>
<br />> >> hvm-3.0-x86_32p hvm-3.0-x86_64
<br />>
<br />>
<br />> >> xen_pagesize : 4096
<br />>
<br />>
<br />> >> platform_params : virt_start=0xffff800000000000
<br />>
<br />>
<br />> >> xen_changeset : unavailable
<br />>
<br />>
<br />> >> cc_compiler : gcc version 4.1.2 20080704 (Red Hat 4.1.2-48)
<br />>
<br />>
<br />> >> cc_compile_by : mockbuild
<br />>
<br />>
<br />> >> cc_compile_domain : centos.org
<br />>
<br />>
<br />> >> cc_compile_date : Wed Jan 5 17:43:03 EST 2011
<br />>
<br />>
<br />> >> xend_config_format : 2
<br />>
<br />>
<br />> >> --------------------
<br />>
<br />>
<br />> >> and then I ran xm top i see
<br />>
<br />>
<br />> >>
<br />>
<br />>
<br />> >> -------------
<br />>
<br />>
<br />> >>
<br />>
<br />>
<br />> >> 5 domains: 1 running, 4 blocked, 0 paused, 0 crashed, 0 dying, 0 shutdown
<br />>
<br />>
<br />> >> Mem: 67099744k total, 43558844k used, 23540900k free CPUs: 16 @ 2527MHz
<br />>
<br />>
<br />> >> NAME STATE CPU(sec) CPU(%) MEM(k) MEM(%) MAXMEM(k) MAXMEM(%)
<br />>
<br />>
<br />> >> VCPUS NETS NETTX(k) NETRX(k) VBDS VBD_OO VBD_RD VBD
<br />>
<br />>
<br />> >> _WR SSID
<br />>
<br />>
<br />> >> Domain-0 -----r 8401 2.4 33554688 50.0 no limit
<br />>
<br />>
<br />> >> n/a 16 4 1892 16848120 0 0 0
<br />>
<br />>
<br />> >> 0 0
<br />>
<br />>
<br />> >> sepmback --b--- 9758 2.6 2105220 3.1 4210688
<br />>
<br />>
<br />> >> 6.3 4 1 0 0 1 0 0
<br />>
<br />>
<br />> >> 0 0
<br />>
<br />>
<br />> >> winserver2 --b--- 5758 0.9 1056644 1.6 4210688
<br />>
<br />>
<br />> >> 6.3 1 1 0 0 1 0 0
<br />>
<br />>
<br />> >> 0 0
<br />>
<br />>
<br />> >> wsusserver --b--- 25812 11.4 3256196 4.9 8404992
<br />>
<br />>
<br />> >> 12.5 4 1 0 0 1 0 0
<br />>
<br />>
<br />> >> 0 0
<br />>
<br />>
<br />> >> zimbra --b--- 26183 7.8 2105220 3.1 4210688
<br />>
<br />>
<br />> >> 6.3 4 1 0 16 1 0 0
<br />>
<br />>
<br />> >> 0 0
<br />>
<br />>
<br />> >> ----------------------
<br />>
<br />>
<br />> >>
<br />>
<br />>
<br />> >> so the above 2 command show me 64gb
<br />>
<br />>
<br />> >>
<br />>
<br />>
<br />> >> Now I m confused ..
<br />>
<br />>
<br />> >>
<br />>
<br />>
<br />> >> Is my Centos XEN server actually using the 64 bit ...
<br />>
<br />>
<br />> >> and which command actually show me the right memory status
<br />>
<br />>
<br />> >
<br />>
<br />>
<br />> > I'm not sure but I think everything is okay with your box. "xm top" shows
<br />>
<br />>
<br />> > that your box run with 64Gb memory, and what "top" shows is that your Dom0
<br />>
<br />>
<br />> > OS runs with 32Gb memory, which means your DomU's take the other 32Gb. Did
<br />>
<br />>
<br />> > you up the memory settings in your virtual hosts configuration? After
<br />>
<br />>
<br />> > doing so you should see the Dom0 memory to go down when looking at it with
<br />>
<br />>
<br />> > "top".
<br />>
<br />>
<br />>
<br />>
<br />>
<br />> Benedict is right. Remember that under Xen Dom0 is really just another VM
<br />>
<br />>
<br />> with special privileges. In fact on all my host systems I restrict Dom0 to
<br />>
<br />>
<br />> 1G of ram by adding a "dom0_mem=1024M" argument to the grub configuration.
<br />>
<br />>
<br />> In practice Xen should reduce the amount of ram used by Dom0 dynamically as
<br />>
<br />>
<br />> needed for VMs i.e. if your virtual machines use 48G of ram then dom0
<br />>
<br />>
<br />> should only show 16G left. A while ago this mechanism lead to instability
<br />>
<br />>
<br />> though so a general recommendation was to set dom0 memory to a fixed 1G or
<br />>
<br />>
<br />> 512M to not rely on this dynamic memory handling.
<br />>
<br />>
<br />>
<br />>
<br />>
<br />> Check this out for example:
<br />>
<br />>
<br />> http://lists.xensource.com/archives/html/xen-users/2008-06/msg00729.html
<br />>
<br />>
<br />>
<br />>
<br />>
<br />> Regards,
<br />>
<br />>
<br />> Dennis
<br />>
<br />>
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