Capacitors
Indeed.
A few years ago I was looking after/inherited a datacentre "thing" for a very large, and very high profile customer. A task was to upgrade all of the firewalls to a new version of software for vulnerabilities and feature reasons. I warned that the age of the firewalls, despite them being under support from the vendor, was such that the capacitors in the PSUs may have dried out and there was risk that they may not reboot after the upgrades. Naturally I got the whole "yeah sure, what would you know" etc response.
I put all of my warnings and recommendations in writing and made sure EVERYONE saw them prior to the upgrade. All of these firewalls had two PSUs, and at least (yes, at least) one in each go them shat themselves. Cue frantic support calls to the vendor to get replacement RMA PSUs.
So, when I got blamed for them all failing and this huge customer cracking the shits, I referred them all to the warnings I sent, the dates they were send and what my suggested ways to avid the issue were. Funnily enough the blame disappeared then.
Biting the hand that feeds IT
