XP Pro: Disaster and Dynamic Disks

From this month this column will feature advice, tips and tricks on getting the most from Windows XP Professional. Of course, in order to migrate my Windows 2000 column to a Windows XP Professional one, I naturally needed to upgrade my workstation to Redmond's latest and greatest operating system.


Unlike in the past, the upgrade process hit several rocks. Although the Windows XP installer recognised the Dynamic Disk and associated Volumes (see the April 2002 Windows 2000 column for a discussion on that topic), and finished successfully, the OS was unable to set a paging file. Trying to do so manually also failed and, what's worse, several services refused to start, citing "access denied", which pointed to a hosed SAM authentication module.

Trying to mend the system by using the Local Security Policy management console and manually editing system user permissions only partially dealt with the problem, and I was still unable to set a paging file.

I decided to install a second copy of Windows XP on a different partition, thinking that I would be able to use the File and Settings Transfer Wizard to shift stuff over to that version, which would, I hoped, work.

However, only the System volume contained a Master Boot Record (MBR) and a partition table; the one to which I wanted to install Windows XP didn't, which is as it should be with Dynamic Disks - after all, the idea behind them is that they break with the past, and shed the old DOS limit of four partitions per disk. This meant that although Windows XP saw the Dynamic Volumes, it wouldn't install on the partition table-less ones.

Next I made an almost fatal mistake: the installer recommended that I delete and recreate the partition on which I wanted to install Windows XP. Being distracted, I thought, "Why not?" and deleted the partition at the end of the disk. Don't do this! If you do, your Dynamic Disk(s) will revert to Basic, and all data on the volumes will be inaccessible.

The correct way to do this is to use the "retain" command of the DISKPART utility, to write a "retainer partition" or a partition table on the Dynamic Volume, and then install Windows XP.


With only a partial backup of important files (like my Operation Flashpoint saved games), and with copy deadlines looming, I cursed my stupidity and began thinking about how to restore the disk. The Recovery Console from the CD-ROM couldn't help me, as it contains no utilities to deal with Dynamic Disks.

When a disk disaster strikes, make sure you don't write anything whatsoever to the disk after the accident. I removed the stricken drive, put in a new one, and installed Windows XP on that.

Then to research Dynamic Disks some more, and to find hints and tips and perhaps a tool with which to bring them back from the dead. Microsoft Support in Sydney responded quickly, and support engineer Nathan Butler recognised what had happened. However, there were limited resources at our disposal. Article Q245725 in Microsoft's Knowledge Base gives you instructions on how to recover accidentally deleted NTFS or FAT32 Dynamic Volumes, by recreating the volumes exactly as before but without formatting them. After you've done that, you use the Rescan command in Disk Management to mount the volumes. Alternatively, you could use the DSKPROBE.EXE sector editor that comes with the NT 4 Resource Kit Support Tools package (available at www.microsoft.com/ntserver/nts/downloads/recommended/ntkit/default.asp) to find and restore a back-up copy of the NTFS boot sector, which is stored at the end of the volume.


Feeling wary of poking at the disk at a low level, I wanted to copy at least some of the data to a safe location, in case I made things worse; time for more research.

Dynamic Disks/Volumes was actually developed by Veritas (www.veritas.com) for Microsoft. Veritas specialises in storage solutions for a vast range of platforms, and the Windows 2000/XP Logical Disk Manager (LDM) is essentially a "lite" version of the company's Volume Manager product. Unfortunately, Veritas doesn't have any products that would help users to recover data from broken LDM disks on Windows.

Mark Russinovich's LDMDUMP tool (www.sysinternals.com/ntw2k/freeware/ldmdump.shtml) showed the 1MB LDM database on the disk to be intact. Oddly enough, the Disk Manager Diagnostics (DMDIAG) tool from the Windows 2000 Resource Kit couldn't read the LDM database at all.

Eventually, I stumbled across R-Studio 2.0 (www.r-tt.com), which promised it understood Dynamic Disks as well as had the ability to recover files from them. Sceptical, I downloaded the demo version, which saw the files and folders I thought were lost forever. R-Studio is a bit pricey at $US49 for the single-filesystem versions ($US179 for the full version which works across a network), but I'm happy to report that it restored all the files I wanted, quickly and neatly. If you're working with Windows 2000/XP, you should consider adding R-Studio to your utilities collection.

It's obvious that NTFS and LDM are robust technologies (my data survived), but as a postscript, I think Microsoft needs to bolster Windows XP's chest of tools for dealing with LDM disks, and make the installer behave more sensibly with them.

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Juha Saarinen

PC World
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