system booted into unexpected kernel

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wolvie
Posts: 4
Joined: 2013/06/14 12:58:38

system booted into unexpected kernel

Post by wolvie » 2015/08/11 14:50:29

Hi,

I have been called in to support an old system running centos5 which was operated by grad students. It is in a strange state where the kernel indicated by uname -a (2.6.18-162.el5) is not in the grub.conf. In addition, the system seems to be a victim of "locked in" syndrome, meaning that the network ports are not available and usb-storage is also not loaded and I cannot get it to load, so the data, which they are desperate to get to, is there, but you cannot get it off.

The system is running 3ware 9550sx raid controller, so I would need another card to move the drives to another system. In addition, the LVM groups together the raid units in a way that makes migration complicated.

My questions are this:

How did it get into this kernel? The users said that they could not get it to boot for a while and thought that when I came to look at it, it would still be unbootable. They had left it in a failed boot state and do not know how it got into the current state.

What is the best way to retrieve the data?
I am concerned that rebooting it will go back in to the unbootable state. Is there a way to load usb-storage or the network drivers without a reboot?
I tried "lsmod | grep usb" which reports that the "usb-storage" module is NOT loaded. I tried running "modprobe usb-storage" but it indicated the module cannot be found (sic). I cannot find /lib/modules/ directory for the current kernel, so this is not surprising.
If there is a way to load the module for either usb or network, I can get the data off. My fallback is booting from a live CD that has 3ware, network and/or usb modules, manually mounting the drives and pulling the data off that way.

This whole thing is a bit more intricate than my normal linux use, so I am concerned about making a mistake and having things go south, especially since 2 of the raid arrays are degraded already. (I have ordered replacement disks to rebuild, but am concerned due to the identical age that another will fail during the rebuild.)

If this is not in the proper location or if I have not read something I should have, please accept my apologies and I will do as advised. Thanks for any help.
Last edited by wolvie on 2015/08/11 20:10:52, edited 1 time in total.

gerald_clark
Posts: 10642
Joined: 2005/08/05 15:19:54
Location: Northern Illinois, USA

Re: system booted into unexpected kernel

Post by gerald_clark » 2015/08/11 15:23:52

I suspect that /boot is not being mounted from /etc/fstab.
The /boot/grub/grub.conf that you are looking at may not be the one in the actual /boot partition.

To get the data off you may have to boot the DVD in rescue mode.

wolvie
Posts: 4
Joined: 2013/06/14 12:58:38

Re: system booted into unexpected kernel

Post by wolvie » 2015/08/28 14:26:58

Good call on /boot not being mounted. Thanks!
(Did someone install a backup kernel there on the other disk? or is this some safety net?)

My question now is, does a rescue DVD come with the 3ware 9550 driver.
If so, how do I make sure the LVM configuration works when I boot with the LiveCD?
There are two raid 5 arrays fused into a single volume with LVM. (Not something I would have done.)

Again, if I need to post elsewhere, please let me know and thanks again for the help.

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