Queries regarding external drives for iMac

[snerkler]

Up until now I've been using portable external drives with my MacBook Pro but have recently purchased an iMac retina and have a couple of queries regarding external drives.

Firstly, are there any advantages of using a desktop external drive with it's own AC supply over a portable drive taking power from the USB? Portable drives are so cheap now (can get 4TB for circa £100) that I don't see any advantage of desktop drives, unless there's some advantage of using mains power.

Secondly, when using external drives with the MBP I always eject them before shutting down/putting to sleep, but with the iMac I'd want to leave them in permanently. Can you shut down/put to sleep without ejecting the drive, and if you can will the drives appear back on the desktop when you start it up again or would you need to unplug/re-plug in for the drive to be recognised?

Lastly, is there any harm stacking the drives (whether portable or desktop) on top of each other such as heat build up, magnetic fields etc?

Any help appreciated.

 

[CoastalOR]

Firstly, are there any advantages of using a desktop external drive with it's own AC supply over a portable drive taking power from the USB? Portable drives are so cheap now (can get 4TB for circa £100) that I don't see any advantage of desktop drives, unless there's some advantage of using mains power.

A portable drive/bus powered will pull power from your iMac bus which if finite. You may run out of power for other connected peripherals. An AC powered drive will need to be manually turned on before starting the iMac and manually shut off after the iMac has shut down. AC powered drives can often support daisy chaining (if they have the ports) and bus powered do not daisy chain.

Secondly, when using external drives with the MBP I always eject them before shutting down/putting to sleep, but with the iMac I'd want to leave them in permanently. Can you shut down/put to sleep without ejecting the drive, and if you can will the drives appear back on the desktop when you start it up again or would you need to unplug/re-plug in for the drive to be recognised?

You do not need to eject the drive before shut down. The process of shutting down will eject the external drives. You can leave them connected permanently. They will automatically mount when you start the iMac (if they are powered on with the AC power switch before starting the iMac. Bus powered drives will automatically power on and mount via the iMac bus as well as automatically eject and power off upon iMac shut down).

Lastly, is there any harm stacking the drives (whether portable or desktop) on top of each other such as heat build up, magnetic fields etc?

Hard to answer without knowing the drives. Generally you can stack them if the drive form factor is stable stacked. Magnetic fields should not be a problem. Heat could be a problem depending on the drives and how hard you use them. I think you would have to monitor them to see how hot they feel. If they feel too warm to you then unstack them or place some spacers between the drives for more clearance and heat dissipation.

 

[snerkler]

Thanks very much for the thorough info, most helpful. It will be very rare that I use other USB devices, but in case I do is the power to the drive/device constant, or if the drive is not being used/data not being transferred does it sort of go into idle and not drain much power?

 

[CoastalOR]

Thanks very much for the thorough info, most helpful. It will be very rare that I use other USB devices, but in case I do is the power to the drive/device constant, or if the drive is not being used/data not being transferred does it sort of go into idle and not drain much power?

The drives use more power when they are in active use.
Here is an article about USB devices power draw:
http://www.tomsguide.com/us/squeezing-more-life-out-of-your-notebook,review-583-26.html

 

[snerkler]

The drives use more power when they are in active use.
Here is an article about USB devices power draw:
http://www.tomsguide.com/us/squeezing-more-life-out-of-your-notebook,review-583-26.html

Many thanks.