[CentOS] how to debug random server reboots

Hi all,

One of our CentOS 5.3 randomly reboots, at different times of the day,
and I can't see why it's doing it.

I have looked through the logs, but don't see any thing in there that
shows me why it has rebooted. How can I debug this?

Here's a snipped from the log, around the time of the reboot:


Jun  2 14:59:59 usaxen02 kernel: EXT3-fs: mounted filesystem with
ordered data mode.
Jun  2 15:00:06 usaxen02 kernel: kjournald starting.  Commit interval 5 seconds
Jun  2 15:00:06 usaxen02 kernel: EXT3 FS on dm-8, internal journal
Jun  2 15:00:06 usaxen02 kernel: EXT3-fs: mounted filesystem with
ordered data mode.
Jun  2 15:00:39 usaxen02 kernel: device vifvenu0 entered promiscuous mode
Jun  2 15:00:39 usaxen02 kernel: ADDRCONF(NETDEV_UP): vifvenu0: link
is not ready
Jun  2 21:00:39 usaxen02 logger: /etc/xen/scripts/vif-bridge: iptables
-A FORWARD -m physdev --physdev-in vifvenu0 -s 72.9.241.226
72.9.241.227 72.9.2
41.232 72.9.247.207 -j ACCEPT failed. If you are using iptables, this
may affect networking for guest domains.
Jun  2 15:00:43 usaxen02 kernel: blkback: ring-ref 8, event-channel 6,
protocol 1 (x86_64-abi)
Jun  2 15:00:43 usaxen02 kernel: blkback: ring-ref 9, event-channel 7,
protocol 1 (x86_64-abi)
Jun  2 15:00:43 usaxen02 kernel: ADDRCONF(NETDEV_CHANGE): vifvenu0:
link becomes ready
Jun  2 15:00:43 usaxen02 kernel: xenbr1: topology change detected, propagating
Jun  2 15:00:43 usaxen02 kernel: xenbr1: port 5(vifvenu0) entering
forwarding state
Jun  2 17:30:22 usaxen02 syslogd 1.4.1: restart.
Jun  2 17:30:22 usaxen02 kernel: klogd 1.4.1, log source = /proc/kmsg started.
Jun  2 17:30:22 usaxen02 kernel: Bootdata ok (command line is ro
root=/dev/VolGroup00/LogVol01 ide0=noprobe)
Jun  2 17:30:22 usaxen02 kernel: Linux version 2.6.18-128.1.10.el5xen
(mockbuild at builder10.centos.org) (gcc version 4.1.2 20080704 (Red Hat
4.1.2-44))
 #1 SMP Thu May 7 11:07:18 EDT 2009
Jun  2 17:30:22 usaxen02 kernel: BIOS-provided physical RAM map:
Jun  2 17:30:22 usaxen02 kernel:  Xen: 0000000000000000 -
00000001de804000 (usable)
Jun  2 17:30:22 usaxen02 kernel: DMI 2.4 present.
Jun  2 17:30:22 usaxen02 kernel: ACPI: LAPIC (acpi_id[0x01]
lapic_id[0x00] enabled)
Jun  2 17:30:22 usaxen02 kernel: ACPI: LAPIC (acpi_id[0x03]
lapic_id[0x02] enabled)
Jun  2 17:30:22 usaxen02 kernel: ACPI: LAPIC (acpi_id[0x02]
lapic_id[0x01] enabled)
Jun  2 17:30:22 usaxen02 kernel: ACPI: LAPIC (acpi_id[0x04]
lapic_id[0x03] enabled)
Jun  2 17:30:22 usaxen02 kernel: ACPI: LAPIC_NMI (acpi_id[0x01] dfl
dfl lint[0x1])
Jun  2 17:30:22 usaxen02 kernel: ACPI: LAPIC_NMI (acpi_id[0x02] dfl
dfl lint[0x1])
Jun  2 17:30:22 usaxen02 kernel: ACPI: IOAPIC (id[0x02]
address[0xfec00000] gsi_base[0])
Jun  2 17:30:22 usaxen02 kernel: IOAPIC[0]: apic_id 2, version 32,
address 0xfec00000, GSI 0-23
Jun  2 17:30:22 usaxen02 kernel: ACPI: INT_SRC_OVR (bus 0 bus_irq 0
global_irq 2 dfl dfl)
Jun  2 17:30:22 usaxen02 kernel: ACPI: INT_SRC_OVR (bus 0 bus_irq 9
global_irq 9 high level)
Jun  2 17:30:22 usaxen02 kernel: Setting APIC routing to xen
Jun  2 17:30:22 usaxen02 kernel: Using ACPI (MADT) for SMP
configuration information
Jun  2 17:30:22 usaxen02 kernel: Allocating PCI resources starting at
d4000000 (gap: d0000000:2ff00000)


-- 
Kind Regards
Rudi Ahlers
CEO, SoftDux Hosting
Web: http://www.SoftDux.com
Office: 087 805 9573
Cell: 082 554 7532