4 ms·

Slamming on the brakes can be hard on the electronics. It causes large, high-speed voltage or current spikes that kill (old, tired) components before the spikes

Slamming on the brakes can be hard on the electronics. It causes large, high-speed voltage or current spikes that kill (old, tired) components before the spikes can be clamped. Can be made worse by old electolytic caps that no longer filter effectively. Especially hard on power supply diodes and mosfets. Here's a few references at random: https://vbn.aau.dk/ws/portalfiles/portal/108034396/ESREF2013_ConferenceVersion.pdf https://vbn.aau.dk/ws/portalfiles/portal/108034396/ESREF2013... https://www.infineon.com/dgdl/s30p5.pdf?fileId=5546d462533600a401535748559c3fcd https://www.infineon.com/dgdl/s30p5.pdf?fileId=5546d46253360... https://www.sciencedirect.com/science/article/pii/S0038110102003283 https://www.sciencedirect.com/science/article/pii/S003811010...

Spivak 5y ago
Which is why if you realize that your hard drive is failing the worst thing you can do is cut the power [1]. You get your data off that box as fast as possible. [1] Yes yes always have backups, and RAID, and replication something about not being able to count that low. Betcha most'a'ya don't have any of that on your MBP though except for a maybe a backup that lags hours behind your work.
CoastalCoder 5y ago
> Slamming on the brakes can be hard on the electronics. It causes large, high-speed voltage or current spikes that kill (old, tired) components before the spikes can be clamped. Suppose that the "slamming on the brakes" here is that the power lines connecting a data center to the grid get physically cut. I can see how that would cause a power spike on the grid side of the cut, but would it really create a spike on the datacenter side of the cut? Or assuming that the wires in a cable aren't cut exactly simultaneously, does it depend on the particular phases of the AC power at the time of each wire in the cable being cut?
- R0b0t1 5y ago
  Any change in the state of an inductive load causes kickback. If you sever the lines running to a building, the generator side gets the most kick, but even a fully passive device gets a kick from the collapsing field in the wires servicing it. The motors generate appreciable back EMF when suddenly unpowered. Likewise an SMPS is an inductive load. Spikes from power supplies going off is probably what killed the disks, assuming they didn't just decide not to power on. Some disks will run for 10 years but power them off once and they don't come back up.

Spivak 5y ago

Which is why if you realize that your hard drive is failing the worst thing you can do is cut the power [1]. You get your data off that box as fast as possible. [1] Yes yes always have backups, and RAID, and replication something about not being able to count that low. Betcha most'a'ya don't have any of that on your MBP though except for a maybe a backup that lags hours behind your work.

CoastalCoder 5y ago

> Slamming on the brakes can be hard on the electronics. It causes large, high-speed voltage or current spikes that kill (old, tired) components before the spikes can be clamped. Suppose that the "slamming on the brakes" here is that the power lines connecting a data center to the grid get physically cut. I can see how that would cause a power spike on the grid side of the cut, but would it really create a spike on the datacenter side of the cut? Or assuming that the wires in a cable aren't cut exactly simultaneously, does it depend on the particular phases of the AC power at the time of each wire in the cable being cut?

R0b0t1 5y ago
Any change in the state of an inductive load causes kickback. If you sever the lines running to a building, the generator side gets the most kick, but even a fully passive device gets a kick from the collapsing field in the wires servicing it. The motors generate appreciable back EMF when suddenly unpowered. Likewise an SMPS is an inductive load. Spikes from power supplies going off is probably what killed the disks, assuming they didn't just decide not to power on. Some disks will run for 10 years but power them off once and they don't come back up.