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  1. #1
    Join Date
    Mar 2006
    Location
    Johannesburg,South Africa
    Posts
    598

    how to optimize CentOS XEN dom0?

    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:

    Code:
    [email protected]:[~]$ 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:


    Code:
    [email protected]:[~]$ free -m
                 total       used       free     shared    buffers     cached
    Mem:           512        472         39          0         13        215
    -/+ buffers/cache:        244        268
    Swap:         4095          0       4095

    Yet, it only has XEN, Webmin (since it's a CloudMin XEN server), Exim, Apache and a few other services running:



    Code:
    [email protected]:[~]$ 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?


    Code:
    The server runs CentOS 5.5 x64:
    
    [email protected]:[~]$ cat /etc/redhat-release
    CentOS release 5.5 (Final)
    
    [email protected]:[~]$ 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 ([email protected]) (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:
    South African Web Hosting - http://www.SoftDux.co.za || SA WebHostingTalk - http://www.webhostingtalk.co.za

  2. #2
    Join Date
    Dec 2005
    Posts
    3,077
    You have 265MB of free memory on Dom0 according to the output of free.

    What's the issue?

    Linux uses RAM as a disk cache, hence the "cached" column.

  3. #3
    Join Date
    Mar 2006
    Location
    Johannesburg,South Africa
    Posts
    598
    Quote Originally Posted by PCS-Chris View Post
    You have 265MB of free memory on Dom0 according to the output of free.

    What's the issue?

    Linux uses RAM as a disk cache, hence the "cached" column.
    Those stats were taken shortly after I had to send a tech to hard reboot server, since it didn't respond to SSH or login on the console.
    South African Web Hosting - http://www.SoftDux.co.za || SA WebHostingTalk - http://www.webhostingtalk.co.za

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