getting kernel crashdumps for hung machines

Fri, 31 Oct 2014 13:53:00 -0700

Debugging hung machines can be a bit tricky. Here I’ll document methods to trigger a crashdump when these hangs occur. What exactly does it mean when a machine ‘hangs’ or ‘freezes-up’? More information can be found in the kernel documentation, but overall there are really a few types of hangs.

A “Soft Lock-Up” is when the kernel loops in kernel mode for a duration without giving tasks a chance to run. A “Hard Lock-Up” is when the kernel loops in kernel mode for a duration without letting other interrupts run. In addition a “Hung Task” is when a userspace task has been blocking for a duration.

setup an external drives as raid1

Mon, 16 Dec 2013 14:37:00 -0800

I purchased a cheap two drive USB enclosure in order to setup an external drive that had RAID-1 so I could backup photos and recordings.

First, I formatted both drives. Then I ran extended smart self-tests to ensure I had decent drives. With RAID-1 and two drives I can only tolerate 1 drive failure.

Next ensure mdadm is installed: sudo apt-get install mdadm

Determine which dev devices the disks show up as. Next, create the raid device pointing at the correct dev directory.

Howto on Chris J Arges

getting kernel crashdumps for hung machines

setup an external drives as raid1