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please append a correct root= boot option HELP! cant boot up linux server!

Posted on 2015-01-06
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Last Modified: 2015-03-09
help!
i have a server that im trying to boot up, but lots of things were done wrong prior to me trying to fix it.
in a nutshell, the server crashed because the power supply went bad.
a tech then started pulling out hard drives during troubleshooting, and i think it broke the raid array (onboard raid controller, its an HP server, cisco branding)
i was able to reinstall grub, and i get to the grub screen where it asks me to choose an OS, but no matter which one i choose, i get the following error-

VFS: cannot open root device "LABEL=/" or 00:00
please append a correct root= boot option
kernel panic: vfs: unable to mount root fs on 00:00

when i reinstalled grub i saw that there were 2 separate hard drives (HDA and HDB). not sure if this should be SDA and SDB, or vice versa?
any ideas? need to get this up and running!!!
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Question by:jsctechy
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Expert Comment

by:Duncan Roe
ID: 40535182
I would boot off a live CD such as Knoppix and see what state the system is in (cat /proc/partitions is a good starting point)
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Expert Comment

by:gheist
ID: 40535262
Which linux distribution?
Usually root=/dev/sda1 or /dev/sda3 ...
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Author Comment

by:jsctechy
ID: 40535679
here is the output of cat /proc/partitions

note- sda and sdb used to be setup in a raid 1 configuration.
im not a linux guy but this seems like its being presented as 2 separate drives, instead of 1 logical drive- am i right?

cat /proc/partitions output
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by:jsctechy
ID: 40535701
im not sure of the linux distribtion but i was told its red hat,
this is actually a Cisco Unified Communications Manager server/appliance (its running on a re-branded hp dl320 server)
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Expert Comment

by:gheist
ID: 40536166
Yes, it is DM mirror.

Use centos 5.11 minimal ISO
Boot in rescue mode
It offers to mount filesystems. If it succeeds - bingo - you have name of root.
If not come back with screenshot.
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by:jsctechy
ID: 40536270
Do you mean the centos netinstall image ? (It's about 15mb)

After typing "rescue mode" it brings me to a screen asking "what type of media contains the rescue image"
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Author Comment

by:jsctechy
ID: 40536390
i was able to boot into knoppix- not sure if im able to do anything with this!
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Expert Comment

by:gheist
ID: 40536400
No. CD 1 or DVD1
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Expert Comment

by:Duncan Roe
ID: 40536519
sda1/sdb1through $sda6/sdb6 look like they could be mirror pairs (identical sizes). That's just my observation though
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Expert Comment

by:gheist
ID: 40536551
Yes, odds are high recovery disk will pick up DM mirror...
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by:jsctechy
ID: 40536665
It keeps asking me "what type of media contains the rescue image?" And then lists
Local CD-ROM
Hard drive
Nfs image
Ftp
Http

If I choose local CD-ROM it says that the CD-ROM doesn't contain a valid rescue image
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Expert Comment

by:gheist
ID: 40536730
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by:jsctechy
ID: 40536987
found the rescue disk this time (i was using ilo and it wasnt working while using ilo image over network i ahd to create a DVD and put it in)
anyway-
when it attempts to look for linux installations it says that none are found
"you dont have any linux partitions. press return to get a shell. the system will reboot automatically when you exit from the shell"
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Author Comment

by:jsctechy
ID: 40536988
i was able to boot up to a knoppix livecd and i was able to mount partitions and browse through them, would this help at all?
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Expert Comment

by:gheist
ID: 40537332
problem is that you need to restore DMRAID configuration.
in present situation you can boot off from one half of mirror (you need to edit /etc/fstab to contain devices and not GUIDs)
Then you need to go long ways to re-estabilish DM mirror back.

At least that way you get back to service quickly.
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Author Comment

by:jsctechy
ID: 40538102
any idea how i would edit the /etc/fstab to do so? :)
FYI im a windows guy trying to help a colleague out!
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Author Comment

by:jsctechy
ID: 40538105
to be honest- im not sure how much i care about the raid array at the moment, if i can get this up and running on 1 drive, i have no problem doing so until we can get upgraded hardware in the environment
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Accepted Solution

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gheist earned 500 total points
ID: 40538126
You need to boot in recovery image
Check mount command output  and make note (on paper) of /dev/sdaX and filesystem mappings
then chroot
inside chroot:
 cp /etc/fstab /etc/fstab.BAK
 nano -w /etc/fstab
 cat /etc/grub.conf > /etc/grub-conf.bak
 nano -w /etc/grub.conf -> change root=/dev/sdaX which one is /
(or use vi if nano is not available)
probably copy files to be modified to other name in case something is missed and you need to redo

you have time to read dmraid instructions and plan putting it back in place.

once system is running: install package "smartmontools" and check smartctl -a /dev/sda
and /dev/sdb - maybe one disk went bad.
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Author Comment

by:jsctechy
ID: 40538195
need to boot into the centos recovery image?
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Expert Comment

by:gheist
ID: 40538284
Yessir! That is the only linux that mounts your partitions.
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Author Comment

by:jsctechy
ID: 40538297
it states that i dont have any linux partitions when i try to boot up with that DVD, not sure why,
ive used rescatux to rebuild the grub and it succeeds, it was able to recognize the linux OS on the partitions
i even have the grub list with all the operating systems when i start the server up

i can browse the files via grub command line as well.
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Expert Comment

by:gheist
ID: 40538395
Try older kernels? Maybe something wass missed with last upgrade.
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