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Some backup programs can wake up a sleeping machine, but there are still a few things that could go wrong and cause a backup to fail.

If my computer is scheduled to backup my files on, for instance, Saturday night, and it's sleeping, does the backup still occur? I'm using Windows 7, 64 bit and receiving a warning that my backup was not successful: "The request could not be performed because of an I/O device error." I'm backing up to a Western Digital external hard drive.

In this excerpt from Answercast #46, I look at a case where a computer's backup program does not seem to be able to kick start a sleeping machine so it can backup in the middle of the night.

Scheduled backups

Well, first let me say, "Good on you for backing up!" Unfortunately, you're in the minority and we're trying to get more and more people to get their data backed up.

Now, the short answer to your question is typically no.

  • If your computer is sleeping;

  • You cannot be guaranteed that the backup program will cause the system to wake up.

And wake up is exactly what it needs to do in order for the backup to process. Ultimately, your machine must be running for a backup to happen.

Automatic wake-up

Now, it is possible that some backup programs will have the ability to kinda-sorta kick your computer awake. Some definitely have the option to wake the computer in order for that backup to run.

In a case like that, it's also possible that the act of waking up the computer and firing up the backup may happen too quickly for the hard disk to actually be ready, because it, too, will have to have woken up and come up to speed, and be recognized by the operating system.

My guess (and it is a just guess, based on the error message that your machine reported to you) is that's probably what's happening here. It's very possible that:

  • Your backup program is starting;

  • And actually is trying to wake up the computer;

  • And trying to initiate the backup;

  • But the hard disk, the external hard disk itself, is taking a little bit longer to wake up.

As a result, when the backup program tries to access that external hard drive, it's not there yet or it's not ready yet.

Leave your computer running

I don't know of a really good solution for this in these kinds of situations other than leaving your computer on. And to be honest, that's what I do.

  • My computers, all of them actually, run 24 hours a day.

At least my primary desktop machine is on (in part) 24 hours a day specifically so that the backup that I have scheduled to run at two in the morning has the opportunity to run.

Reliably waking up

So ultimately, I think that while it may be possible for backup programs to wake up a computer to perform a backup, it's not necessarily something that's going to be reliable on every machine (or every combination of machine and hard drive.)

What I recommend in your case is to:

  • Simply leave the machine running;

  • Or change the scheduled backup to a time when you know the machine will in fact be up and running.

Article C5726 - August 23, 2012 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

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1 Comment
Theo Deed
August 26, 2012 12:29 AM

When I want a program to run at a specific time, I have my machine scheduled waking up some 10 minutes earlier. I have no password for my account as I am the only person to use my computer. To make the schedule I use the Administrator account that has a password. The latter seems to be necessary for making a schedule.

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