David’s Opinions

I’ve got 2 x USB hard drives connected to my AEBS and the Airport has disk sharing configured with user accounts.
I found an issue the other week… I thought I’d backed up my data to my “personal drive” on the AEBS… only now the drive had nothing in it!

Turns out that the AEBS (had been restarted at some point) and was now presenting my personal drive off the “other” hard drive…

I’ve been searching for an explanation on this tonight and while I’ve not been able to find anything on the web, I eventually ran help in the Airport Utility

AirPort Extreme (802.11n): Using an attached USB storage device as a home directory is not recommended

You should not use a USB storage device connected to an AirPort Extreme (802.11n) base station as a home directory. An AirPort Extreme (802.11n) base station may not be able to locate a home directory on an attached USB device if it is powered off or if the enumeration order of attached storage devices changes.

Article: 305013
http://docs.info.apple.com/article.html?artnum=305013

So… if it’s not recommended to set up the AEBS in this way, why allow the option in the configuration? Oh and how many people are going to understand what the word enumeration means anyway?

A few weeks ago I brought a weather station from a local electronics retrailer (Jaycar). It was high up in their catalogue and was promoted as having a USB PC interface and a TV interface. Well here we have yet another manufacturer who only distributes windows software with their devices.

My idea was to be the next person in my area with an online weather station, one where you could hit my web site and see what the current conditions at my house are. And the crippled windows software supplied with the weather station only displays data to the connected PC.

Getting this thing internet connected means that I’d need to understand what the USB protocol is that the weather station is using with the PC software… enter USBSNOOP for windows (it’s a sourceforge project), some time, a bit of luck, and oh a quick note to the manufacturers to see if they would give me a copy of the USB specification for this device. The response was a polite bit firm “Unfortunately this is proprietary and is information that we can not disclose“.

I can advise that on the Mac I am successfully retrieving data (wind direction, temperature, humidity, pressure, etc) from the weather station. One data element remains to be decoded at time of writing, along with a bulk startup data sequence.

I’m working on building the Mac program now. The interface won’t be flash - it’s more to prove it works. When this is done I will look at the web interface part. I want to run this on a Mac running its built in web server. Actually I’m thinking PPC Mac Mini - it will be silent and if I can find a second hand one, quite cost effective.

If you would like details of the USB Protocol specification that I have thus far, send me an e-mail and I can share what I have.

FootNote: 2 April 2008 - have largely decoded output information from the Weather Station and have the details displaying on screen in a program that anyone can use. The GUI doesn’t have any dials or fancy stuff, but does have some “bars” for representations of temperature etc (as well as their decimal equivalents showing). Oh and I only show Celsius at this point, that is what is coming from the Weather Station.

Apple released TimeCapsule and Airport 1.0 last week and since then various blog sites and forum postings have been filled with comments about now being able to backup using Time Machine to disk attached to an AirPort Extreme base Station. Sadily, I could not.And I’ve figured out that the disks attached to my AirPort Extreme Base Station were setup at a time when my Mac was running 10.4.x (not Leopard)… Anyway, this fix worked for me… read on…

I’ve got 2 x external hard drives connected to my AirPort Extreme base station. The base station disk sharing is configured to be on with user accounts created and as it happens at the moment guest access read/write (though I suspect that doesn’t matter). [an interesting side note with 2 drives, is that "my personal drive" created by having user accounts now has nothing in it where it once did - it's on the 1st or 2nd hard drive and the Air Disk utility is showing me the other drive]…

anyway back to the Time Machine subject…

1. Using Airport Utility, disk connect all users of your hard drives.
2. Physically disconnect your USB disks and connect to your Mac.
3. At this point a file is created on your hard disk (may well not have been there before) “.com.apple.timemachine.supported”. The file has no contents.
4. I then copied the file into the Shared folder on both volumes - doing this using sudo from terminal of course
5. I then copied the file into the Users/<my user> on the volume that was sharing user folders - same as above
5. Also while I had the drives connected to the Mac directly, I took the opportunity to run disk utility and First Aid repair disk (which found and fixed errors on both drives).
6. Unmount disks from Mac
7. Connect back to AirPort Extreme Base Station
8. Run TimeMachine (turn on)…. look mum I can see volumes to back up to!

backup in progress…

credit to the posting at TUAW by tobias