Hi, I have a problematic CentOS XEN server and hope someone could point me in the right direction to optimize it a bit. The server runs on a Core2Quad 9300, with 8GB RAM (max motherboard can take, 1U chassis) on an Intel motherboard with a 1TB SATA HDD. dom0 is set to 512MB limit with a few small XEM VM's running: root at zaxen01:[~]$ xm list Name ID Mem(MiB) VCPUs State Time(s) Domain-0 0 512 4 r----- 96.5 actionco.vm 3 1519 1 -b---- 14.8 byracers.vm 4 511 1 -b---- 85.7 ns1 5 511 1 -b---- 22.3 picturestravel 6 255 1 -b---- 13.3 rafttheworld 7 255 1 -b---- 11.3 zafepres.vm 8 511 1 -b---- 19.0 the server itself seems to eat up a lot of resources: root at zaxen01:[~]$ free -m total used free shared buffers cached Mem: 512 472 39 0 13 215 -/+ buffers/cache: 244 268 Swap: 4095 0 4095[/CODE] Yet, it only has XEN, Webmin (since it's a CloudMin XEN server), Exim, Apache and a few other services running: root at zaxen01:[~]$ chkconfig --list |grep "3:on" |awk '{print $1}' |sort acpid auditd crond csf dhcpd exim haldaemon httpd iptables iscsi iscsid kudzu lfd lvm2-monitor mdmonitor network qemu restorecond setroubleshoot smartd snmpd sshd syslog sysstat webmin xend xendomains Is there anything I can optimize on such a server? The server runs CentOS 5.5 x64: root at zaxen01:[~]$ cat /etc/redhat-release CentOS release 5.5 (Final) root at zaxen01:[~]$ uname -a Linux zaxen01.softdux.com 2.6.18-194.32.1.el5xen #1 SMP Wed Jan 5 18:44:24 EST 2011 x86_64 x86_64 x86_64 GNU/Linux with Xen version 3.1.2-194.32.1.el5 And there's the xm dmesg output: Xen version 3.1.2-194.32.1.el5 (mockbuild at centos.org) (gcc version 4.1.2 20080704 (Red Hat 4.1.2-48)) Wed Jan 5 17:43:03 EST 2011 Latest ChangeSet: unavailable (XEN) Command line: dom0_mem=512M (XEN) Video information: (XEN) VGA is text mode 80x25, font 8x16 (XEN) VBE/DDC methods: V2; EDID transfer time: 1 seconds (XEN) Disc information: (XEN) Found 1 MBR signatures (XEN) Found 1 EDD information structures (XEN) Xen-e820 RAM map: (XEN) 0000000000000000 - 000000000008f000 (usable) (XEN) 000000000008f000 - 00000000000a0000 (reserved) (XEN) 00000000000e0000 - 0000000000100000 (reserved) (XEN) 0000000000100000 - 00000000cf53f000 (usable) (XEN) 00000000cf53f000 - 00000000cf54b000 (reserved) (XEN) 00000000cf54b000 - 00000000cf620000 (usable) (XEN) 00000000cf620000 - 00000000cf6e8000 (ACPI NVS) (XEN) 00000000cf6e8000 - 00000000cf6ec000 (usable) (XEN) 00000000cf6ec000 - 00000000cf6f1000 (ACPI data) (XEN) 00000000cf6f1000 - 00000000cf6f2000 (usable) (XEN) 00000000cf6f2000 - 00000000cf6ff000 (ACPI data) (XEN) 00000000cf6ff000 - 00000000cf700000 (usable) (XEN) 00000000cf700000 - 00000000d0000000 (reserved) (XEN) 00000000fff00000 - 0000000100000000 (reserved) (XEN) 0000000100000000 - 0000000230000000 (usable) (XEN) System RAM: 8181MB (8378020kB) (XEN) Xen heap: 13MB (13720kB) (XEN) Domain heap initialised: DMA width 32 bits (XEN) Processor #0 7:7 APIC version 20 (XEN) Processor #2 7:7 APIC version 20 (XEN) Processor #1 7:7 APIC version 20 (XEN) Processor #3 7:7 APIC version 20 (XEN) IOAPIC[0]: apic_id 2, version 32, address 0xfec00000, GSI 0-23 (XEN) Enabling APIC mode: Flat. Using 1 I/O APICs (XEN) Using scheduler: SMP Credit Scheduler (credit) (XEN) Detected 2485.797 MHz processor. (XEN) HVM: VMX enabled (XEN) VMX: MSR intercept bitmap enabled (XEN) I/O virtualisation disabled (XEN) CPU0: Intel(R) Core(TM)2 Quad CPU Q9300 @ 2.50GHz stepping 07 (XEN) Booting processor 1/2 eip 90000 (XEN) CPU1: Intel(R) Core(TM)2 Quad CPU Q9300 @ 2.50GHz stepping 07 (XEN) Booting processor 2/1 eip 90000 (XEN) CPU2: Intel(R) Core(TM)2 Quad CPU Q9300 @ 2.50GHz stepping 07 (XEN) Booting processor 3/3 eip 90000 (XEN) CPU3: Intel(R) Core(TM)2 Quad CPU Q9300 @ 2.50GHz stepping 07 (XEN) Total of 4 processors activated. (XEN) ENABLING IO-APIC IRQs (XEN) -> Using new ACK method (XEN) Platform timer overflows in 2 jiffies. (XEN) Platform timer is 1.193MHz PIT (XEN) Brought up 4 CPUs (XEN) *** LOADING DOMAIN 0 *** (XEN) elf_parse_binary: phdr: paddr=0xffffffff80200000 memsz=0x2f4d70 (XEN) elf_parse_binary: phdr: paddr=0xffffffff804f4d80 memsz=0x14c510 (XEN) elf_parse_binary: phdr: paddr=0xffffffff80642000 memsz=0xc08 (XEN) elf_parse_binary: phdr: paddr=0xffffffff80644000 memsz=0x11be8c (XEN) elf_parse_binary: memory: 0xffffffff80200000 -> 0xffffffff8075fe8c (XEN) elf_xen_parse_note: GUEST_OS = "linux" (XEN) elf_xen_parse_note: GUEST_VERSION = "2.6" (XEN) elf_xen_parse_note: XEN_VERSION = "xen-3.0" (XEN) elf_xen_parse_note: VIRT_BASE = 0xffffffff80000000 (XEN) elf_xen_parse_note: PADDR_OFFSET = 0xffffffff80000000 (XEN) elf_xen_parse_note: ENTRY = 0xffffffff80200000 (XEN) elf_xen_parse_note: HYPERCALL_PAGE = 0xffffffff80206000 (XEN) elf_xen_parse_note: FEATURES = "writable_page_tables|writable_descriptor_tables|auto_translated_physmap|pae_pgdir_above_4gb|supervisor_mode_k ernel" (XEN) elf_xen_parse_note: LOADER = "generic" (XEN) elf_xen_addr_calc_check: addresses: (XEN) virt_base = 0xffffffff80000000 (XEN) elf_paddr_offset = 0xffffffff80000000 (XEN) virt_offset = 0x0 (XEN) virt_kstart = 0xffffffff80200000 (XEN) virt_kend = 0xffffffff8075fe8c (XEN) virt_entry = 0xffffffff80200000 (XEN) Xen kernel: 64-bit, lsb, compat32 (XEN) Dom0 kernel: 64-bit, lsb, paddr 0xffffffff80200000 -> 0xffffffff8075fe8c (XEN) PHYSICAL MEMORY ARRANGEMENT: (XEN) Dom0 alloc.: 0000000222000000->0000000224000000 (122880 pages to be allocated) (XEN) VIRTUAL MEMORY ARRANGEMENT: -- Kind Regards Rudi Ahlers SoftDux Website: http://www.SoftDux.com Technical Blog: http://Blog.SoftDux.com Office: 087 805 9573 Cell: 082 554 7532