Pie Charts Lie

Do these two charts appear to even remotely depict the same information? Supposedly they do. Is it just some sort of optical illusion?




"Almost there, buddy!"








"You might as well switch majors."

Apple's Bootcamp bungles GPT specification

Ever wonder how Bootcamp works? Well, Apple has basically messed up the GUID partitioning standard to make it work with Windows, even though they could have just stuck with MBR and kept things simple. It is a horrible, horrible kludge. We finally figured out what this guy already found; partitioning and imaging a Macintosh is a real bastard, but possible. And no, Bombich's software (although pretty cool), just doesn't cut it when you already have a PC solution (Altiris Deployment) and a Mac solution (Xserve+NetInstall).

The GUID specification calls for a "protective MBR" with exactly ONE partition (with an ID of 0xEE). No matter how many partitions you create in the GUID table, there should only be ONE partition in the MBR table. ONE!

What Apple has done is make a hybrid GPT/MBR. In this case, "hybrid" is synonymous with "bastardized". Any partition you create (with apple tools) in the GUID table gets copied to the MBR table. This is why when you install bootcamp, you CANNOT remove the partition and recreate it; the geometry would not match what is in the GUID table. Once the two tables are out of sync, it's a real bastard to fix. ReFIT has a program called gptsync that will sync one way; GTP to MBR... but there is no reversal of that.

The really funny part is Apple's Tech Note from 2006 (probably just before BootCamp). They describe the Protective MBR as "a single partition entry (of type 0xEE) that covers the entire area of the disk used by GPT structures and partitions." A single parition? A Bootcamp Mac has three!

Furthermore, Apple mentions "Specifically, if block 0 contains an MBR with more than one partition entry, or a single partition entry whose OSType is not 0xEE, it is not a compliant GPT disk, and manipulating the GPT may cause dangerous inconsistencies between it and the legacy MBR."

and they follow that with a:

WARNING: Failure to comply with this recommendation may result in the loss of user data.

So there you have it... Apple's GPT support is completely laughable and confusing as hell. They completely violate their own recommendations not to mention the specs.

Ironically, I can use Apple's DiskUtility to format a Leopard Mac with good old MBR and 2 partitions. I can restore a Windows XP image (via RapiDeploy) and a Mac image (via netinstall) to these partitions, and THEY ARE BOTH BOOTABLE just FINE. The caveat is, you can only boot from EFI (holding the option key). Once you're in Mac OS or Windows, NONE of your disks appear in the startup disk preference pane (you can't even select the disk you are booted to). It's kinda sad when EFI is smarter than your proper OS...

Don't get me wrong; EFI and GPT are totally awesome technologies-- I just hope we can stick to the standards. This means Microsoft: Get on the ball and support EFI and GPT for Windows XP and Vista. And to Apple: Why don't you stick with MBR for dual-boot Macs? You only support 2 usable partitions anyway!

Another Marpac Sleepmate/Soundscreen 980A Review

There is already a really good review of this sound machine over here, except they didn't really tear the thing apart.

Inside: At the heart of the Marpac 980A is a high-efficiency Jakel J238-038-3325 C Frame Motor. Ok, it's just a fan.

That's really all there is to it. If it ever breaks, you can find replacement motors online. These are the same motors used in bathroom exhaust fans. You can find motors like these for under $10 at surplus sites online. So, if you're really cheap you can spend a lot less than $50 and build your own. Of course, it will be ugly and probably cause a fire. . .

The Marpac Sleepmate/Soundscreen 980A is rated "less than 40 watts". I was concerned that this sound machine might use more power than our iBook (which previously served as our sound machine via the nifty Noise utility), so I decided to test the Marpac with a KillaWatt.

I was surprised that at low speed the unit only draws 6 watts.

On high, 13 watts. This is considerably less than the .33 amps (39 watts) that the motor is rated for. I'm not really sure why this is the case; perhaps because the motor is hardly under any load, having been fitted with such small fan blades? In any case, it'll cost less than $10/year to run 8hrs/day. Probably closer to $2.

Ok, finally, here's a video of the unit in action, at BOTH speeds!

Overall, we're very happy with the noise that the machine produces. Although it is a lot different than the Noise application, I think it is more soothing and has a much larger range of sound, probably due to the fact that the speakers in an iBook can't create any bass to speak of. I am also very sensitive to "sound loops" produced by some electronic noise machines, and of course this machine is completely immune to that. Overall it is a simple, low-tech solution to an old problem, and more elegant than a box fan.