Great! After setting dom0_mem=1024M, I can start all 5 nodes of my Rocks HPC cluster without crashing dom0 as compared to the previous limit of 3 nodes when I did not set dom0_mem. Thank you Pasi! Another resource problem solved. Here's my latest grub.conf: # grub.conf generated by anaconda # # Note that you do not have to rerun grub after making changes to this file # NOTICE: You have a /boot partition. This means that # all kernel and initrd paths are relative to /boot/, eg. # root (hd0,0) # kernel /vmlinuz-version ro root=/dev/mapper/vg_fedora11_host-lv_root # initrd /initrd-version.img #boot=/dev/sda default=4 timeout=100 splashimage=(hd0,0)/grub/splash.xpm.gz hiddenmenu title Fedora (2.6.31.5-xen-enming.teo) root (hd0,0) # kernel /vmlinuz-2.6.31.5-xen-enming.teo ro root=/dev/mapper/vg_fedora11_host-lv_root rhgb quiet selinux=0 # initrd /initrd-2.6.31.5-xen-enming.teo.img kernel /xen.gz dom0_mem=1024M iommu=1 module /vmlinuz-2.6.31.5-xen-enming.teo ro root=/dev/mapper/vg_fedora11_host-lv_root rhgb quiet selinux=0 nomodeset module /initrd-2.6.31.5-xen-enming.teo.img title Fedora (2.6.31.4-xen-enming.teo) root (hd0,0) # kernel /vmlinuz-2.6.31.4-xen-enming.teo ro root=/dev/mapper/vg_fedora11_host-lv_root rhgb quiet selinux=0 # initrd /initrd-2.6.31.4-xen-enming.teo.img kernel /xen.gz dom0_mem=1024M iommu=1 module /vmlinuz-2.6.31.4-xen-enming.teo ro root=/dev/mapper/vg_fedora11_host-lv_root rhgb quiet selinux=0 nomodeset module /initrd-2.6.31.4-xen-enming.teo.img title Fedora (2.6.31.1-xen-enming.teo) root (hd0,0) # kernel /vmlinuz-2.6.31.1-xen-enming.teo ro root=/dev/mapper/vg_fedora11_host-lv_root rhgb quiet selinux=0 # initrd /initrd-2.6.31.1-xen-enming.teo.img kernel /xen.gz dom0_mem=1024M iommu=1 module /vmlinuz-2.6.31.1-xen-enming.teo ro root=/dev/mapper/vg_fedora11_host-lv_root rhgb quiet selinux=0 nomodeset module /initrd-2.6.31.1-xen-enming.teo.img title Fedora (2.6.31-enming.teo) root (hd0,0) kernel /vmlinuz-2.6.31-enming.teo ro root=/dev/mapper/vg_fedora11_host-lv_root rhgb quiet selinux=0 initrd /initrd-2.6.31-enming.teo.img title Fedora (2.6.30.5-enming.teo) root (hd0,0) kernel /vmlinuz-2.6.30.5-enming.teo ro root=/dev/mapper/vg_fedora11_host-lv_root rhgb quiet selinux=0 initrd /initrd-2.6.30.5-enming.teo.img title Fedora (2.6.18.8-enming.teo) root (hd0,0) # kernel /vmlinuz-2.6.18.8-enming.teo ro root=/dev/mapper/vg_fedora11_host-lv_root rhgb quiet selinux=0 # initrd /initrd-2.6.18.8-enming.teo.img kernel /xen.gz dom0_mem=1024M iommu=1 module /vmlinuz-2.6.18.8-enming.teo ro root=/dev/mapper/vg_fedora11_host-lv_root module /initrd-2.6.18.8-enming.teo.img title Fedora (2.6.31-rc6-enming.teo) with Serial Console root (hd0,0) # kernel /vmlinuz-2.6.31-rc6-enming.teo ro root=/dev/mapper/vg_fedora11_host-lv_root rhgb quiet selinux=0 # initrd /initrd-2.6.31-rc6-enming.teo.img kernel /xen.gz dom0_mem=1024M iommu=1 iommu_inclusive_mapping=1 com1=115200,8n1 console=com1 # module /vmlinuz-2.6.31-rc6-enming.teo ro root=/dev/mapper/vg_fedora11_host-lv_root selinux=0 xencons=ttyS0 console=ttyS0,115200 module /vmlinuz-2.6.31-rc6-enming.teo ro root=/dev/mapper/vg_fedora11_host-lv_root selinux=0 console=hvc0 earlyprintk=xen module /initrd-2.6.31-rc6-enming.teo.img title Fedora (2.6.30-rc3-enming.teo-tip) with Serial Console root (hd0,0) # kernel /vmlinuz-2.6.30-rc3-enming.teo-tip ro root=/dev/mapper/vg_fedora11_host-lv_root rhgb quiet selinux=0 # initrd /initrd-2.6.30-rc3-enming.teo-tip.img kernel /xen.gz dom0_mem=1024M iommu=1 iommu_inclusive_mapping=1 com1=115200,8n1 console=com1 # module /vmlinuz-2.6.30-rc3-enming.teo-tip ro root=/dev/mapper/vg_fedora11_host-lv_root selinux=0 xencons=ttyS0 console=ttyS0,115200 module /vmlinuz-2.6.30-rc3-enming.teo-tip ro root=/dev/mapper/vg_fedora11_host-lv_root selinux=0 console=hvc0 earlyprintk=xen module /initrd-2.6.30-rc3-enming.teo-tip.img title Fedora (2.6.31-rc6-enming.teo) root (hd0,0) # kernel /vmlinuz-2.6.31-rc6-enming.teo ro root=/dev/mapper/vg_fedora11_host-lv_root rhgb quiet selinux=0 # initrd /initrd-2.6.31-rc6-enming.teo.img kernel /xen.gz dom0_mem=1024M iommu=1 module /vmlinuz-2.6.31-rc6-enming.teo ro root=/dev/mapper/vg_fedora11_host-lv_root rhgb quiet selinux=0 nomodeset module /initrd-2.6.31-rc6-enming.teo.img title Fedora (2.6.30-rc3-enming.teo-tip) root (hd0,0) # kernel /vmlinuz-2.6.30-rc3-enming.teo-tip ro root=/dev/mapper/vg_fedora11_host-lv_root rhgb quiet selinux=0 # initrd /initrd-2.6.30-rc3-enming.teo-tip.img kernel /xen.gz dom0_mem=1024M iommu=1 module /vmlinuz-2.6.30-rc3-enming.teo-tip ro root=/dev/mapper/vg_fedora11_host-lv_root rhgb quiet selinux=0 nomodeset module /initrd-2.6.30-rc3-enming.teo-tip.img title Fedora (2.6.29.4-167.fc11.x86_64) root (hd0,0) kernel /vmlinuz-2.6.29.4-167.fc11.x86_64 ro root=/dev/mapper/vg_fedora11_host-lv_root rhgb quiet selinux=0 initrd /initrd-2.6.29.4-167.fc11.x86_64.img -- Mr. Teo En Ming (Zhang Enming) Dip(Mechatronics) BEng(Hons)(Mechanical Engineering) Alma Maters: (1) Singapore Polytechnic (2) National University of Singapore My Primary Blog: http://teo-en-ming-aka-zhang-enming.blogspot.com My Secondary Blog: http://enmingteo.wordpress.com My Youtube videos: http://www.youtube.com/user/enmingteo Email: space.time.universe@gmail.com Mobile Phone (Starhub Prepaid): +65-8369-2618 Street: Bedok Reservoir Road Country: Singapore On Mon, Nov 9, 2009 at 8:18 PM, Pasi Kärkkäinen wrote: > On Mon, Nov 09, 2009 at 08:14:27PM +0800, Mr. Teo En Ming (Zhang Enming) > wrote: > > What is a good value for dom0_mem if I want to start X server and run > > GNOME? Will 512 MB be too little? > > > > Go for 1024 MB then.. > > -- Pasi > >