Hard disks fail sometimes. No big deal, you just replace it. But what if a hard disk fails in a ZFS array with few dozen disks? How can you locate the correct disk? There is a nifty tool for that called ledctl.

Let’s say the failed disk is /dev/sdh - all you need to do is just turn the correct led on with the following command: ledctl locate=/dev/sdh

Then just replace the blinking disk, and you are good to go. 

To turn the blinking off just use the command: ledctl locate_off=/dev/sdh