A computer acting more strangely than usual

[alitalf]

I set the computer into sleep mode when I had to go out, so that I could take up typing the email I was part way through later. But, when I came to start using it again, pressing the power button made no difference.

So, I switched off the output of the UPS until the blue light stopped flashing, then switched it back on again and hit the computer's power switch.

It returned to the state it had been in before I set it in sleep mode, half-written email and all. Not that I am complaining, but I wish I knew how that happened. Could it have anything to do with having upgraded to a solid state drive recently?

Comments

[adalger]

It's called hibernation. The computer basically writes its state to disc and shuts down. Then, next time you turn it on, it sees that saved state and loads it up.

[alitalf]

If it had been normal hibernation I would not have been surprised. In hibernation, the power switches off far enough for the blue light not to flash as it does in sleep mode.

Even in hibernation (or off) mode a small amount of power is drawn, enough to operate the power-up logic so that the computer can switch on. BUT, in hibernation the blue light does not flash and it would be possible to disconnect the computer from the mains completely, leave it for hours or days, and return to where you were.

My best guess, and it really is a guess, is that the power rail which flashes the blue LED discharged its capacitors before the one holding up the RAM. That doesn't quite make sense because there is a lot of RAM, and refresh cycles must take a certain amount of power.

I suppose another possibility is that the computer automatically stored a hibernation file for no obvious reason, then returned to a semi-crashed sleep mode instead of powering off properly. That doesn't make complete sense either.

[bens_dad]

There is a suspend-hybrid mode which writes the date to disk like hibernation, then goes into sleep mode (keeping power to the RAM) so that it can come back almost instantly when requested.
I assume that this allows laptops to go to a state that recovers quickly, use very little power but doesn't lose data if the battery does go completely flat.

My guess is that your machine crashed while in this suspend-hybrid state, as your second possiblity suggests.