29113 Views Previous 1 2 3 Next 38 Replies Latest reply: Oct 13, 2009 7:19 AM by cornelius Go to original post
Take a look and search MacIntouch and others. In 2008, just holding down 'D' on startup IF you used the original OEM drive, it was installed from the factory with AHT; or, if you used the OEM DVD to install (someone here tested for that).
Intel Macs came with 10.4.x, OEM only, never retail, on DVDs, but AHT was on #1 (part of dual-layer design).
Having AHT on hard drive never removed the ability to still use it the old way, from DVD, just another option - created in part to allow MacBook Air to run AHT. - you don't even need a hard drive to run AHT off DVD (yes you need optical drive that functions).
*MacBook Air: Using Apple Hardware Test Application*
*Mac OS X 10.5 Leopard: Using Apple Hardware Test after erasing your disk*
Some Intel-based Macs ship with Apple Hardware Test and Mac OS X 10.4.x preinstalled on the hard drive. If an Erase and Install installation of Mac OS X 10.5 Leopard is performed using a retail Leopard installation disc, Apple Hardware Test will be erased and not reinstalled on these Macs.
Cornelius, I think that only MacBook Air's + maybe a few recent Mac models come with the drive formatted with an extra partition that has AHT on it. None of my 2008 models do.
It was my understanding that this partition was not touched by installers (including Snow Leopard's), in the same way that for instance a Windows partition would not be. AHT isn't really an application; in effect it is a tiny little operating system purpose built to test the hardware, so it acts just like any other selectable boot partition.
AFAIK, the only way to remove it is to reformat or replace the drive, so I'm wondering if that explains what has happened here & in similar reports.
Anyway, personally I would not trust it anywhere near as much as the version on the system disc set: because it is on rewritable (& therefore corruptible) magnetic media, it could itself be damaged or affected by damage to the partition scheme info on the drive. This isn't possible with read-only media like a DVD ROM.
I wondered if installing 10.6 would alter or "disrupt" the ability or remove access to, or the AHT routine and partition. Guess it does.
A normal upgrade won't muck with the AHT routine or partition; however, if you elect to erase the boot volume, repartition, and install SL, then apparently you can muck things up. I haven't tried doing that, but simply upgrading for over a year while beta-testing SL didn't muck with AHT. See the +Apple Hardware Test Read Me+ file that shipped with the machine.
I am not aware that launching AHT from the HDD during boot was ever possible, so that confuses me.
Described by +The Hatter+. It's a new feature (started Jan '08, according to the AHT document referenced above) with all Macs. Alternatively, you can pop in the install disk and start it by rebooting and holding down the D key.
I'm an eraser-head, when I upgrade an OS as you probably are aware, that means I really start from ground up, and not just over top of the old system, which I feel isn't the best method.
Odd that erasing even JUST the system volume, not erasing the entire drive (which seems to be the "new" initialize) removes it, which means it didn't rely on a small hidden "dDrive" if you will.
MicroMat has its own "eDrive." Windows 7 has 100MB system recovery emergency boot partition. No unique partition - one that could be read-only, and while bad block might occur, should be as safe as your GPT and EFI is. One reason I initialize is so that the old tables are recreated, their blocks retested, and sometimes the volume information block is enlarged or changed. Or shifted by an offset.
Operating systems still need manuals! or at least end users. People are walking around in the dark hitting up against walls, shine some light on how things work.
Described by +The Hatter+. It's a new feature (started Jan '08, according to the AHT document referenced above) with all Macs.
Not true. The Apple document says, "Some Intel-based Macs ship with Apple Hardware Test and Mac OS X 10.4.x preinstalled on the hard drive."
FWIW, all my Intel Macs are 2008 models. All shipped with Leopard installed. None have seen an Erase & Install of any OS. None will start up into AHT with the "D" key unless the appropriate DVD is inserted, no would they before they were upgraded from Leopard to Snow Leopard.
Message was edited by: R C-R
It is said that it is better to remain silent and be thought ignorant than to open one's mouth and confirm it. Not true. While revealing my ignorance I have often opened myself to new learnings, as in this instance. I thank you all. My MBP is an Early 2008, but since I was unaware of the possibility I have not tested it to see if I could boot from AHT. Next time I shut down I will try it. I stand enlightened. Thanks, again.
Reading the document and the manual section on restoring the software that came with the machine doesn't indicate anything WRT AHT, so I surmise that it isn't on a different partition, but would activate via the D key. I've never done a so-called +clean install+ on my G4 or iMac and have beta-tested Panther through Snow Leopard w/o any issues. The +clean install+ method is, IMO, way over-blown.
The best manuals for OS X are the Apple Training Series ones, while Pogue's missing manuals fill the void for non-power users.
I change / swap / reformat drives. Doesn't matter why, but they don't stay as is or the same that long. And move from SoftRAID to Apple and back again along the way.
I did see issues with corrupt drivers; with 6.07 not working with an upgrade of the driver, and I tend to find clean to work better, smoother - the two times I did an upgrade was I just to test and 10.4.0 already had known issues.
While at it, 10.4.4 made changes that affected SCSI setups and I had to move 10K and 15K drives to separate channels. When it comes to system, I use 10K drives for last 9 yrs probably. I never liked PATA and even when I tried to like 7.2k drives it wasn't a love fest.
So... stripping a drive of all partitions makes sense to me. And I'd challenge someone to scan their drive in Windows for weak sectors before they use it. I know Mac OS doesn't return or report write and read errors fully according to SoftRAID (they do try to report recoverable and non-recoverable errors). HFS is old and has its weaknesses.
I also tend not to trust the "never" and "always" reports - from any source. No system or drive, and 10.5.0 had its issues with mounting drives, so why should I trust it?
I helped one G5 owner that couldn't instll OS, hadn't initialized the drive in two years or since 10.3.? and had been running Tiger. A full drive ERASE and they didn't have trouble. So why not?
Okay, I don't install more than once or twice over an OS version. But that once is clean. So we are in the same ballback probably. I just use the latest versions of Disk Utility to initialize the drive before restoring.
You really should try one of the 10K VelociRaptor, or Samsung F3 now that they are out. Or, there is SSD for those so inclined!
FWIW, the new installer does not install Snow Leopard 'over the top' of the old OS. That description is a apt one for what the old OS installers did with their "Upgrade" option, but it bears essentially no resemblance to how the new installer works. (I don't need a manual or light to tell me this, just the install log file on any of the Macs I have upgraded to Snow Leopard -- but I admit a manual would be nice.)
I do find it curious that the Leopard installer would erase whatever AHT is on the factory formatted drive during an Erase & Install.