How to reliably detect disk is down on Linux via Java

Question

Is there a good way to detect that particular disk went offline on server on Linux, via Java?

I have an application, that due to performance reasons, writes to all disks directly (without any RAID in middle).

I need to detect if Linux would unmount any disk due to disk crash during run-time, so I would stop using it. The problem is that each mount has a root directory, so without proper detection, the application will just fill-up the root partition.

Will appreciate any advice on this.

Answer 1

In Linux, everything is accessible through text files. I don't really understand what is the exact information you require, but check /proc/diskstat, /proc/mounts, /proc/mdstat (for raids), etc...

Answer 2

As anyone with sysadmin experience could tell you, disks crashing or otherwise going away has a nasty habit of making any process that touches anything under the mountpoint wait in uninterruptible sleep. Additionally, in my experience, this can include things like trying to read /proc/mounts, or running the 'df' command.

My recommendation would be to use RAID, and if necessary, invest your way out of the problem. Say, if performance is limited by small random writes, a RAID card with a battery backed write cache can do wonders.