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I just got an Airport Extreme Base Station. I am planning to use this one replace my current Linksys router. This works fine. My another purpose of getting this device is to use its USB port to connect to several external HDs as my backup Time Machine.

I can see one 500GB HD through Airport Base Station. However, I cannot format it by using Disk Utility. What I did is to connect the HD to my iMac directly first and then clean and format the disk by Disk Utility application. Then I move the HD to the Airport Base Station. After that I can designate the HD as my Time Machine destination.

Is there any way to format the HD connected to Airport Base Station? Any issues to use an external HD through Airport Base Station for Time Machine backups?

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I've been through this process and there are a few gotchas (which you'll find if you google similar problems).

Details here:

But in summary:

You can only format the drives by attaching them direct to a Mac (or PC if you must). It's not possible to format a drive connected to the Airport Extreme.

So, connect each drive to the Mac and format it to HFS+ (Mac OS X Extended Journaled). Be sure to set the partition scheme to GUID, as well as format the partition to HFS+.

They are set separately and it's possible to have a drive partitioned as Master Boot Record (likely the factory default) and the partition formatted to HFS+ (or FAT32, the likely factory default format). In this instance the Mac will read them and they'll seem fine when connected via USB but the AE will fail to recognise it, turn the indicator light orange and report "Disk needs repair". This is true even if there is only one partition on the drive.

(The Airport Extreme does not support NTFS but you're using Macs so that shouldn't be an issue).

From there plug them into your USB splitter and plug the splitter into the Airport Extreme. They should now be visible through finder.

To backup through Time Machine you simply open Time Machine preferences (through System Preferences or the Time Machine icon in the bar at the top), specify the drive and you're good.

The first back up will take a long time so it's best to connect your machine directly to the Airport Express using a network cable. Even with this backing up 100Gb could take 10 hours.

One common error is doing the first back up by connecting the hard drive direct to the Mac via USB. This doesn't work - Time Machine won't then recognise that back up file when it's connected via the Airport Express - you need to connect the drive to the Airport Express via USB / Firewire and then connect the Mac to the Airport Extreme using a network cable.

But generally it works fine, I've been doing it for over a year now without problems.

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See this article : "How to Setup Time Machine on an Airport Extreme Basestation".

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Based on the information there, it does not say about formatting HD from AEBS. I did almost the same steps as the link recommended. I just missed the step to make the HD as one partition. I'll try again. – Sep 28 '09 at 20:49
I looked, but haven't found anything about formatting the HD from AEBS. – harrymc Sep 29 '09 at 5:49

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