2 October 2006

Vitsa's Maintenance OS

This is one of the best bits of news I had from the Vista Labs a few months back! We were told to spread the word about what wasn't NDA, but this item was NDA at the time, so I had to sit on it. But today' Google( Vista boot DVD WinPE ) shows it's public knowledge now :-)


This turns what would have been a crisis (would Bart CDR boot be compatible with Vista's NTFS, registry, etc.?) into what may be a reason for cautious consumers to favor Vista over XP.

I tested Vista beta 2 a while ago in a bit more depth than recent time permits with the newer Customer Preview build I have now, and it's certainly come a long way since that earlier build. I specifically wanted to test the mOS, and that turned out to be very interesting indeed...

Those familiar with Bart PE would guess what I'd be looking for first - can it boot off a USB stick? Can you hot-swap USB flash drives? Can you use the optical drive or will the system crash if you eject the Vista boot DVD? Is there a GUI?

No, there's no GUI - it's more like Safe Mode Cmd Only, which is a good thing in many ways. I'd have been worried in Explorer was there as the shell, in case Vista's richer shell offered exploit surfaces to malware on the maintained system.

Yes, you can eject the boot DVD! In this recent build I tested, the Vista installation DVD is the mOS boot disk, and just as you'd UI your way to Recovery Console after booting an XP CD, so it is that you GUI your way to "command prompt", which is likely to be WinPE 2.0 itself.

After booting, the DVD gets a different drive letter, compared to the booted OS files. The free space and a few other cursory tests indicated these were different volumes, and neither is an alias of hard drive space. You can eject the Vista DVD, insert other CDRs or DVDRs, and use them directly. I suspect the mOS runs from a RAM drive - and it worked quite happily in 512M RAM. What I didn't check was whether it uses a page file on the HD.

Vista development takes off from the most recent Server 2003 SP1 code base - and this is a good code base for a mOS, because it no longer resets the USB during the boot process, as XP SP2 does. So the odds are favorable for booting Vista mOS off USB flash drives, etc.

Unlike a Bart boot, Vista mOS will "see" USB flash drives inserted and changed on the fly - they don't have to be present at boot time, as they do with Bart, and swapping them is OK too. (Tip for Bart users; a memory card reader present at boot will generally allow hot-swapping of cards after boot - so I share SD cards between Bart sessions and my camera, instead of using slower and more write-limited flash drives).

Running tools from Bart CDR

Just for laffs, I ejected the Vista DVD and popped in my Bart CDR. The nu2menu (the standard "Start buttom" menu shell for Bart) worked fine, and many of the tools worked too. Because the Bart drive letter is not the same as the boot drive letter, my own "Is this booted or Autorun?" batch file logic, e.g....

Set Prog=Ad-Aware.exe
Set Launch=%~dp0..\RunScanner\RunScanner.exe
Set Opt=/m /t 0


If "%SystemDrive%"=="%~d0" (
Start %Launch% %Opt% %~dp0%Prog%
) Else (
Start %~dp0%Prog%

...concludes Bart is being run from the "native" system OS, and not as the booted OS.

That means my tools weren't running through RunScanner, which is probably prudent at this stage. Yes, that means registry-orientated tools such as AdAware or HiJackThis will not "see" the HD installation's registry, but until we know RunScanner and legacy registry access methods are compatible with Vista's registry, it's safer this way.

Many tools didn't work, because they relied on files and settings within the running OS. The Bart plugins for these tools would have included these in the Bart mOS, but that's not the OS that's in effect here - so if these resources aren't in the standard Vista code set, then the tools won't work. That's to be expected; after all, if I'd just scraped them onto Bart without using the plugin system, they wouldn't have worked there either.

All this testing was with the original Vista DVD - I haven't gone as far as building a new Vista mOS boot disk, nor have I explored "plugging in" tools as one does for Bart. I'm not sure if either of these things would be possible, or whether the answers would change between the build I tested and the final release.

Ah, for the time to really explore this stuff!


It's really good news to see a mOS for Vista, even if it's still not really orientated to mOS work. For example, it won't operate unless there's a visible Vista installation on the hard drive, and the RAM testing component writes to and then boots from the hard drive installation - both of which are bad practices when dealing with systems that are really ill.

I think this is because the mOS is still rooted in its origins as a "(p)re-install environment", originally intended for use on perfect fresh hardware. It was somewhat in response to this, as well as seeing some Bart off-shoots that also break some mOS best-practices, that prompted an earlier "How to design a maintenance OS" post in this blog.

The important things is that it's there, on the installation DVD (a break-through, if you'd ever peered longingly at MS WinPE though the previous licensing sphincter) and that the architecture seems fundamentally sound. It needs to be tested more rigorously to see how well it stays within the rules of mOS best practice, but it's already more than I'd dared hope for!

No comments: