I recently noticed that Time Machine on both my Macs (Mountain Lion, 10.8.3) seem to think that my Airport Extreme base station (AEBS) + USB hard drive is actually a Time Capsule. Screenshots below. BTW, I asked this question on the official support status of AEBS + USB HDD, but this question is different (though related)

Question: Why does Time Machine (on Mountain Lion) think that an AEBS with an external HFS+ USB drive is a Time Capsule? I don't recall doing anything special but are there some special settings that "make it so"?

TM thinks it's backing to a Time Capsule

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TM performing a backup to the USB HDD (HFS+) attached to the AEBS

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1 Answer 1


Apple only supports backup to Time Capsule, so the wording there is a constant and not something designed to know it's not backing up to Time Capsule as opposed to an actual server or directly connected drive.

You can test this (since I doubt they recently changed course on this with an update) by connecting a totally new drive to the Airport Extreme, wipe the drive from AirPort Utility and then try to set up Time Machine to back up to that newly erased drive.

  • I actually did just that! That is, setup a freshly formatted disk to the AEBS and time machine picked it up without a problem. In fact the screenshot shows it making the first backup just after formatting and pointing it to time machine! May 18, 2013 at 6:35
  • Cool! Mine doesn't work that way, and the official docs say it shouldn't work, but I know you could get around that design in the past.
    – bmike
    May 18, 2013 at 12:39

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