Hello, "By default, XenServer automatically tunes the dom0 settings during
installation. IIRC, on a 4G system, ~768MB gets allocated to dom0. The defaults should work just fine for you. dom0_mem = 502MB + int(physical_mem * 0.0205) *Table 2.1. Default Dom0 Memory Size* Physical Memory Dom0 Memory 2 GB 543 MB 4 GB 585 MB 8 GB 669 MB 16 GB 837 MB 32 GB 1173 MB 64 GB 1845 MB 128 GB 3188 MB 256 GB 5875 MB 512 GB 11249 MB 1024 GB 21997 MB 2048 GB 43493 MB Hello, Citrix Xen related questions should probably be asked on the Citrix Xen mailing lists :) Actually; His question is regarding dom0 Sizing WITH His Configuration of 4GB RAM. So it shouldn't be on Citirx Xen; it applies to CloudStack hardware builders too or anyone running Apache CloudStack ON physical hardware (I'd imagine most everybody is here on this mailing list). > By default, XenServer automatically tunes the dom0 settings during > installation. > IIRC, on a 4G system, ~768MB gets allocated to dom0 > Here, we use the following sizing computation rules: Rule: dom0_mem = 502 + int(physical_mem * 0.0205) You should always dedicate a fixed amount of RAM for Xen dom0. This can be done by specifying "dom0_mem=512M,max:512M" option for the Xen hypervisor (usually xen.gz) in grub.conf/menu.lst. This makes sure that the initial amount of memory allocated for dom0 is 512 MB (note: Replace this value with the amount of memory you want to allocate to dom0) and leaves the rest of the host system's RAM available for other guests. See this grub.conf example for GRUB1: *Table 2.1. Default Dom0 Memory Size* Physical Memory Dom0 Memory 2 GB 543 MB 4 GB 585 MB 8 GB 669 MB 16 GB 837 MB 32 GB 1173 MB 64 GB 1845 MB 128 GB 3188 MB 256 GB 5875 MB 512 GB 11249 MB 1024 GB 21997 MB 2048 GB 43493 MB http://wiki.xen.org/wiki/Xen_Best_Practices#Xen_dom0_dedicated_memory_and_preventing_dom0_memory_ballooning
