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-0005.html>