nixCraft

while i am booting the linux i am getting kernal panic error.what are the possible ways to troubleshoot this problem.thanx in advance.


with rgds,

ramjimh

Resolving a kernel panic is not a simple task. You need to provide us exact error message. For example few days back my new kernel stop at boot up with the error message
Kernel panic: VFS: Unable to mount root fs on…

What message do you see? Please post message so that we can help you further

Are you using 64 bit AMD/Intel EM64T based kernel? Many servers have problem to boot 64bit SMP servers so boot into single UP mode server. Type following two parameters at Grub prompt
In addition, boot system into single UP mode then update your kernel and try it out again

Also as pointed by tom it is better if you give us exact kernel panic message. Otherwise, we cannot guess your message and it will make delay for you to get solution

__________________
Rocky Jr.
You may have my body & soul, but you will never touch my pride!

If you have knowledge, let others light their candles at it.

Certified to work on HP-UX / Sun Solaris / RedHat

can you give me general troubleshooting guide lines for kernal panic errors.i don't know the exact errors.if you give general troubleshooting for linux it will be useful for future purpose.

with rgds,

ramjimh

ramjimh,

If you get error Kernel panic: VFS: Unable to mount root fs…

a) It means initrd image is missing
b) Or image does not include fs kernel modules to access the filesystem on the partition

Solution boot from rescue cd and try to resinstall fresh copy of kernel from CD or RHN

If you see mysterious kernel hangs/ kernel Freezes at boot time then enable sysrq support in kernel See doc how to enable Reboot or halt Linux system in emergency http://www.cyberciti.biz/nixcraft/vi...system-in.html

__________________
Rocky Jr.
You may have my body & soul, but you will never touch my pride!

If you have knowledge, let others light their candles at it.

Certified to work on HP-UX / Sun Solaris / RedHat

You need to enter nosmp and maxcpus parameter at Grub or Lilo boot prompt. For example if you are using Grub as a boot loader, at Grub prompt press 'e' to edit command before booting.

1) Select second line
2) Again, press 'e' to edit selected command
3) Go to end of line and type two parameters
nosmp maxcpus
4) Press enter twice and b to boot system
5) This will prevent the kernel panic and system hang scenario.
Once your system is up using single CPU then you can run diagnostic commands such as:

Get all boot message:
Find out if problem with PCI cards
Find out what device drivers loaded (if something is missing then your driver will not get loaded)
Get memory info (is memory detected correctly?)
Get CPU info (see if your CPU hit by any bug):
Find out your kernel version:
If kernel is old then update it to latest stable release from RHN using up2date command

__________________
Vivek | My personal blog
Linux Evangelist
Play hard stay cool

Mod stick out this post as it got some good info

Done

__________________
Vivek | My personal blog
Linux Evangelist
Play hard stay cool

i had big bad time with a faulty mother board. its ram went for a toss, motherboard went for a toss, ide cables were rat chewed and smps was choking for fresh oxygen.
check the motherboard for tight connection setup.
check smps for proper power supply. thats why i got decent UPS and had to redo the wiring.
change ide/sata cables if cable gets chewed
ram is tossed? then run memtest86 or memtest86+
if these arent issues? then check for the health of the harddrive. run a check on IO status of the cylinders of harddrive. run fsck with real verbose mode. in ext2/3 we dont have any defragment option. and defragment is not necessary, because it got -j option in mkfs.conf which stands for journaling. when issuing fsck check for cylinder error and also bad blocks. and make sure bad blocks are not in the boot sector. else? kiss it bye bye. KIBB.
if everything is fine? run gdb if you are a little advanced user and if you are a little advanced than a little advanced user? "then kdb, because once is kernel? YOU START TO PANIC." run a kdb trace. and locate the exact source of the error and fix it. scramble, search, shoot, execute and fix!
happy rebooting.