kpozin.net Projects & Musings by Konstantin Pozin

In Windows Vista, there’s a feature called “hybrid sleep.” It works by combining hibernation and standby modes.  When you put your computer into hybrid sleep mode:

1. the contents of the computer’s memory are copied to disk (hibernate mode)
2. the computer then goes into a low-power mode that doesn’t let you interact with the computer, but keeps data alive in memory (standby mode)

This has one possible benefit: as long as your computer maintains power, you can quickly resume from standby. If the power dies, you don’t lose data; the computer just resumes from the hibernation file stored on disk, which is slower than wake-up from standby, but theoretically faster than having to boot your computer and restart all your applications.

Here are the downsides:

• Dumping memory to disk takes a very long time. Instead of going into standby in 5-10 seconds, you wait 1-2 minutes for the hibernation file to be created before your computer actually goes to sleep. This would be fine if you could just start the process by closing your laptop’s lid, and get going, but:
  • It’s extremely unreliable. Vista, for whatever reason, often hangs in the process. You might close the lid thinking the computer will just dump memory to disk and go to sleep in a minute or two, but instead find an hour later that it has been chugging along and overheating instead of ever going to sleep.
  • It’s not a good idea to start moving your laptop while the hard drive is still running. When you pack up your laptop, put it in a backpack, and start walking, the computer is subjected to a lot of motion that doesn’t happen during normal use. This isn’t so good for the physical health of a hard drive that’s spinning at 7200 RPM; the computer should remain relatively stationary whenever the hard drive is not parked. Once solid-state drives become commonplace, this will cease to be a concern, but on your current laptop, it’s a problem.

Coming out of standby works pretty well, but resuming from hibernate tends to be painfully slow and unreliable.

• The computer can usually resume from standby to a usable state in 5-15 seconds, in my experience. However, if you have the misfortune of resuming from hibernate, you’ll find that Vista will take a couple of minutes to resume to the login screen, and then another 2-4 minutes until it’s stopped thrashing the hard drive and is actually useable.
• Of course, you’ll sometimes not succeed in resuming from hibernate at all. Sometimes there’s a Blue Screen of Death. Sometimes the hard drive never stops thrashing upon resume. Go figure.

So here’s the upshot:

You want to reduce the possibility of data loss if your laptop somehow loses power. This can only happen if it is both unplugged and the battery dies while it’s on standby, without hybrid sleep enabled. A full battery can sustain your laptop for a few days in standby mode, so this is actually a non-issue. What is an issue, however, is the unreliability of hibernate; hibernation is almost guaranteed to cause you more cold reboots and data loss. On top of that, it wastes your time on both ends, causes you stress because you’re often unsure whether it’s actually going to do something or just thrash the hard drive for an indeterminate period of time, and has the potential to physically damage your computer while you’re in motion.

So disable hybrid sleep! It’s easy to do.

• Control Panel > Power Options
• Change plan settings
• Change advanced power settings
• Sleep > Allow hybrid sleep > Off