Does Time Machine prevent sleep?

A backup utility that let's the computer sleep wouldn't be very useful since it would die in the middle of a backup if the computer went to sleep. You definitely do not want the computer going to sleep during backups.

Well, in theory. I'm not really sure what TM does if, for example, the computer is asleep prior to the time of the next backup. TM may not wake up the computer and simply skip over the backup until the computer is awake whenever a scheduled backup comes up. But TM should not abort if the computer's sleep time arises during a backup. It should keep the computer awake until the backup finishes. This should be how any backup utility should work, but then you never know for sure until you test them. For me I would want to test any backup utility's behavior under circumstances that might compromise the backups insofar as I depend on the backup utility's reliability to produce usable backups without my having to be constantly in attendance.

I've tried TM several times since Leopard's release, and in general do not consider it a reliable backup alternative. I have had varied results with backups and restores, particularly with restores. TM seems to backup OK, but I haven't had any success doing a complete system restore. I'm also concerned by the many trouble reports appearing on these forums. There are just too many problems reported for me to consider TM truly reliable. However, that said there are a lot of users who seem to have no problems with TM. I guess I just sort of think a backup utility should really be bullet-proof because it's so important.

Kappy wrote:
A backup utility that let's the computer sleep wouldn't be very useful since it would die in the middle of a backup if the computer went to sleep. You definitely do not want the computer going to sleep during backups.

Hi,

That is not how its supposed to work:
http://www.apple.com/macosx/features/300.html
+Never skip a beat. If your Time Machine backup is interrupted — because you took your portable on the road or put your Mac to sleep — Time Machine will simply stop backing up. When you reconnect to your backup drive again, Time Machine automatically picks up where it left off.+

Best Wishes,

Mitch

That is not how its supposed to work:
http://www.apple.com/macosx/features/300.html
+Never skip a beat. If your Time Machine backup is interrupted — because you took your portable on the road or put your Mac to sleep — Time Machine will simply stop backing up. When you reconnect to your backup drive again, Time Machine automatically picks up where it left off.+

Best Wishes,

Mitch

The devil is in the details. One would expect that they meant Time Machine will start backing up again, not that the backup in progress would be completed later. That would mean that all data on the system drive would have to maintain it's state, or Time machine would have to start keeping multiple copies on the system drive until backups were started again.

Not on my machine! I have tried the initial back-up (that I know takes a long time) on my MB with Time Mach for the 4th time now. I set my sleep preferences (computer & display) to never & screensaver to never. Still shuts down everything in about an hour. It was starting from the beginning every time. Today is the first day that it picked up where it left off. Still not happy.

Little help here??

I'm at 4GB of 43.82 onto a 500GB Time Capsule! Grrrrrr
Internet and wireless printing are wonderful though

Well, with TM the backups should just be suspended and then resumed when the computer comes out of sleep. Technically TM should not interfere with any system functions, and the computer should go to sleep at the scheduled times in the energy saver settings.

OK I think I fiqured this out. The Security setting was set to log out automatically in 1 hour. I unchecked it. Let's see what happens now.

Unfortunately, I think Time Machine does prevent sleep, assuming you have Energy Saver set to sleep after an hour or more...

Appears that a Time Machine backup is consider "activity," so as far as Energy Saver is concerned, with Time Machine turned on, you're using your computer every hour, so you'd have to set a very short Energy Saver interval to get the computer to sleep automatically.

I consider this a bug--obviously, there's no reason to keep backing up the computer when it's not really being used. In my opinion, Time Machine should not trigger a reset of the Energy Saver clock. That way, your computer could go to sleep automatically, instead of being interrupted every hour by Time Machine.

With Time Machine around, it's kinda like trying to get to sleep in a hospital...

James

Fortunately it works that way and it is not a bug.

If Time machine is running and the users manually sets the computer to sleep, then TM stops and resumes when the computer wakes up. If TM is working and there is no activity, other than TM, the energy settings don't take over and TM will finish the back up. That is why it might be a good idea to set the display to turn off after 15 minutes or less of inactivity. Once TM finishes, by default the next backup will be in 1 hour, but if your sleep settings are to sleep after 1 hour of inactivity, it will go to sleep and it will not be waken up by TM from its sleep. That makes sense and I am glad it works that way.

I should have said that it is better to set the computer to sleep after 10 or so minutes of inactivity, the monitor after 3 to 5 minutes, and select the hard drive to sleep when possible. That way I would avoid the discussion about the never ending loop: hourly backup vs. sleep after 1 hour of inactivity, which comes first?

Anyhow, you get the idea of how it works and why it is a good thing it does it that way

Two months ago I decided that PC was ruining my life..I got a mac book then an IMAC....so really I don't know anything yet but....

in power settings you can send your MAC to sleep if it is idle or the display to sleep if it is idle (sorry to state the obvious)...I noticed if I send the MAC to sleep while TM is running it stops, so why would it wake up the MAC ?.

Seems to me why would you want the TM backing up when the Mac is sleeping..nothing is changing.=, why not switch off TM then when run when convenient.