Does it feel like it takes forever to copy or retrieve a file from an AirPort Disk? It may be possible that your network is not optimized to provide the highest througput that it can offer ... but how do you get a objective measurement to compare against?
There are a few things to take into consideration, namely:
- The throughput between your Mac and the AirPort Extreme Base Station (AEBS) or Time Capsule (TC), and
- The throughput between your Mac and the USB HDD attached to the AEBS or TC.
For comparison I did a couple of simple tests for my network. In my case, I tested throughput using an Intel Mac mini and an 4th generation 802.11n AEBS. Attached to the AEBS is a Western Digital Passport USB HDD. The basic network path between them is: Mac mini > wireless > AEBS > WD Passport. As you can imagine, you can have literally hundreds of other network configurations and each will be unique for their overall throughput characteristics.
I first measured throughput from the Mini to the AEBS by using IPNetTunerX. I used iPNetTunerX's Link Rate test tool. I did five runs and the average throughput was found to be 115 Mbps (14.4 MBps).
To measure throughput to the WD Passport, I first created a 1 GB disk image file using the Disk Utility. I then copied this file to a folder on the MiniStack. To get the throughput reading I used Net Monitor. I could have easily used OS X's Activity Monitor for this as well. I did five runs of copying this file and the average throughput was found to be 95 Mbps (11.88 MBps). A second way to run a throughput test to the AirPort Disk is to use AJA System Test. System Test will automatically create a temporary file and perform read/write tests, then delete the file when done.
As I expected the throughput to the AirPort Disk would be lower as it would be additive. All in all, it took under 2 minutes to transfer the file.
You can perform similar tests to determine if the issue is the connection to the AEBS/TC or to the external USB HDD that you are using. These two values should not be off more than 20-25%. If they are, I would suspect the USB HDD. If both are extremely low, then it would indicate the connection to the AEBS/TC will require further troubleshooting.