Airport Extreme and external hard drive

To give you some comparsions to work with, I used AJA System Test to take some data throughput tests between my Mac mini and: 1) An external USB HDD (Seagate 2 TB mounted in a drive caddy), 2) An external Firewire 800 HDD (WD 2 TB mounted in a drive caddy that supports Firewire 800), and 3) An AirPort Disk attached to my 4th generation 802.11n AirPort Extreme Base Station (AEBSn).

The following were the results:

• Test 1 (External USB HDD): 33.5 MBps (read) / 27.9 MBps (write)
• Test 2 (External Firewire 800 HDD): 77.8 MBps (read) / 67.2 MBps (write)
• Test 3 (AirPort Disk): 5.7 MBps (read) / 5.4 MBps (write)

The connection between the mini and the AEBSn is Gigabit Ethernet through two Ethernet switches. The AirPort Disk itself is a WD My Passport USB powered HDD. These were designed for portability, not necessarily performance. Using a higher performing HDD may provide better results, but you can be sure that you will not get any where near the same throughput performance as that when the HDD is externally connected to your Mac.

For some kinds of files, that will work, but access will of course be somewhat slower.

If you're doing photo editing, however, that will be quite sluggish, at best.

Video editing is impossibly slow -- iMovie won't even work with files on a network.

I was completely flummoxed by the horrible 1 MBps (read) performance from my AirPort Disk and tried everything (including a bunch of sysctl hints, staring at wireshark traces, connecting directly over Ethernet), but nothing helped.

But when I removed the cheap USB hub situated between the AirPort Extreme and the hard drive, reads improved to 4 MBps.