Unable To Boot CentOS 6 – Segmentation Erorr
Hi all, I had an issue this morning with one of my virtual machines. It wouldn’t boot (into any runlevel), nor could I chroot into the root partition using a rescue disk.
Unfortunately I didn’t grab a screenshot, however the error(s) when booting were:
/pre-pivot/50selinux-loadpolicy.sh: 14
init: readahead main process (425) killed by SEGV signal init: readahead-col lector main process (421) killed by SEGV signal init: rcS pre-start process (425) killed by SEGV signal init: Error while reading from descriptor: Bad file descriptor init: readahead-col lector post-stop process (424) killed by SEGV signal init: rcS post-stop process (427) killed by SEGV signal init: readahead-disable-services main process (428) killed by SEGV signal
When using a rescue CD and chrooting into the root partition, I would get :
Segmentation Fault: Core Dumped
In the end, the fix was to boot into a rescue CD with networking, and SCP
the entire contents of /bin and /sbin from another (working) server to the broken installation. This finally allowed CentOS 6 to boot correctly.
So I’m left to assume some of the files in /bin *or */sbin were corrupt.
My question is, does anyone have any ideas on how this might have happened?
I did do a quick memory test using the rescue CD (it didn’t complete) and there weren’t any errors. The virtual machine is running on VMWare with 3
other VMs, which all seem fine. There wasn’t any unexpected power loss either.
Thanks.
2 thoughts on - Unable To Boot CentOS 6 – Segmentation Erorr
Also, the last message in /var/log/messages before the crash was:
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29 07:30:10 *hostname* kernel: imklog 5.8.10, log source = /proc/kmsg started
Which seems very concerning.
Hi John,
TL;DR: prevention.
I can’t say what happened, but I’ve a long-standing dread of your situation. Here’s some ways to prepare for (or prevent)
the next time this happens. Possibly you’re already doing all this but a recitation here might help someone else too.
– Set up remote logging. I favor rsyslog, but you can also
use syslog-ng. Have one central logging server. This way you
can look for signs of trouble that preceded the crash.
– Keep baselines from the guest VMs. You can run rpm –verify
and preserve the output off-host (last step in yum update).
Disable the nightly pre-link behavior (was this ever a good
idea?) to make comparing results more meaningful.
Post-crash, mount the victim read-only and re-run the verify
to pin-point what part of the filesystem was clobbered.
Knowing what was clobbered (and when) can help. Not long ago
an errant script in production cleared the wrong
directory but only when transaction volume crested some
threshold, wiping out a critical monitoring script.
– Treat your hosts like cattle, not pets. Automating creation
and maintenance of hosts gives you more and better options
for recovery when hosts go insane.
– Test and re-test your storage system. There are bugs lurking
in every storage code base and every HBA’s firmware. The
physical connectors in your data path are built on a mass
of compromises and contradictory design goals and are just
waiting to fail. Flush bugs out before putting gear into
production.
– Restores, not backups, are your friends.[1] I ran into a
bug in Gnu tar (this year) that left me with silently
corrupted archives but only for thin-provisioned virtual
filesystems >16GB that compressed to <8GB. Only a full
restore unearthed the ugly truth.
– Consider ECC RAM. Once you have a few tens of GB’s you’ve
essentially got your own cosmic ray detector. If you
figure your time at $50/hour and it takes ten hours to deal
with with one ephemeral mysterious incident then springing
for $500 worth of ECC RAM is a good bet. Figure in the cost
of downtime and it’s a no brainer.
Best regards,