iMac sleep while copying, transfer fails when woken

[slvrscoobie]

Hey all, trying to see if anyone else has this issue and what I can do to fix it.
My wife uses her 5K imac for wedding photography and she transfers huge amounts of data, 100gb at a time for some long weddings. So a lot of times she'll walk away or start a transfer before going to bed. Even at USB3, it takes a half hour or more. (Internal hybrid drive to external backup)
But this morning (and a couple of other times now) shes woken the display to find the transfer has failed. Not exactly sure why, but the first time it happened, I changed a few settings. On Yosemite, I clicked the box that said 'Dont sleep when display turns off' or whatever it says.
So theoretically it should stay on all the time, and realistically, it shouldn't matter as its Doing something, sleep should not be activated.
Anything Im missing here, what can I do to keep it from doing this.

 

[existe]

Get Caffeine app

 

[hfg]

Open SystemPreferences/EnergySaver and set the ComputerSleep slider to "Never Sleep" when you are doing the transfer. It shouldn't matter what setting the DisplaySleep slider is in.

 

[slvrscoobie]

That's not an option in this model (see attached). So I have the display turned off after an hour and the tick box to 'prevent sleep when display turns off'. But I don't understand why a transfer would stop if the display turns off. Unless it's still going to sleep? As soon as the touch the mouse of keyboard, it's right at the lock screen so I don't think it's sleeping....?

 

[hfg]

That's not an option in this model (see attached). So I have the display turned off after an hour and the tick box to 'prevent sleep when display turns off'. But I don't understand why a transfer would stop if the display turns off. Unless it's still going to sleep? As soon as the touch the mouse of keyboard, it's right at the lock screen so I don't think it's sleeping....?

What version of Yosemite are you running, and on what iMac?

On my 10.10.5 screen I see these controls:

 

[Blujelly]

Get Caffeine app

I agree, I have this app for when I'm downloading, really easy. Either set to never sleep or you can do my pre-made minutes / hours

 

[slvrscoobie]

10.10.4 - 5K imac, I have this

 

[hfg]

Not sure if this will help ... but doing a PRAM reset does seem to cure a lot of ailments. You might also try moving the DisplaySleep slider to "Never" and just dim the display overnight to see if that works.

Otherwise, I too have the Caffeine app and it does work.

 

[slvrscoobie]

Had it on my MBP for a long time. So long I forgot I had it a few times and couldn't figure out why the display was on all night. I'll have to do more tests. Obviously it doesn't seem to be as stable as 'don't sleep' checkbox would have you imagine.

 

[CoastalOR]

Maybe try moving the display off slider to 1 Hr as an experiment. That would hopefully allow enough time for the transfers to complete.

 

[Lankyman]

If I don't put the computer sleep slider higher up the scale when copying large files, cloning VM etc. then it will sleep after approximately 15 minutes. However, it doesn't cause the task to fail but simply pause.

When I wake up my iMac the task continues to completion.

I have occasionally experienced the problem you mention and the cause is almost always down to the fact that I haven't done a cold boot for quite some time. A simple restart always cures the issue.

 

[slvrscoobie]

Had another one last night where it was uploading via Java app. Got 300 of 1200 uploaded and failed.