BackupPC and Bare Metal Restore of Windows XP

While it’s not well documented, it’s possible to do a bare-metal restore of a machine running Windows XP that’s been backed up via BackupPC (assuming, of course, that some method, such as that documented here, has been used to back up open files, such as the registry.)

Step 1:  Build a local tar file using BackupPC_tarCreate

The alternative, BackupPC_zipCreate, proved problematic; the gigantic archives that it created could not be completely recovered, yet tar archives proved intact.  At any rate, this is best accomplished from the command line, as the backuppc user:

BackupPC_tarCreate -t -n -1 -h borkstation -s C / > borkstation.tar

“borkstation” is the name of the host to recover, “-n -1″ means the latest backup, and you’ll obviously need to have enough space where the tar file is going to store the entire backup, which will not be compressed.  Note the space between the “C”, which represents the share to restore, and the “/”, which represents the directory to restore.

Step 2:  Prepare bare XP

Basically, you want to install a working copy of the operating system.  Aside from network drivers, it really doesn’t matter if anything’s installed or working, you’re going to wipe it all out anyway.  The filesystem and the partitions will stay, so configure those the way that you want your system to finally end up.

Step 3:  Prepare Recovery Console

Using the same install CD, you can install the recovery console to speed things up a little versus booting from the CD, although either option will work.  To install the recovery console, use Start->Run, then

d:\i386\winnt32.exe /cmdcons

Where D: is the letter if the CD-ROM.  Whether you choose to install it or not isn’t really important, but what is important is that you open up the permissions for Recovery Console, or some of the remaining steps won’t work.

  1. Start->Run, then type secpol.msc
  2. Go to Security settings->Local policies->Security options
  3. Scroll down to “Recovery console: Allow floppy copy and access to all drives and all folders” and make sure it is enabled.

Step 4:  Install Cygwin

You’ll need a “tar” utility you can rely on for the next step, and experimenting with a plethora of them has shown that unless you build your own, you’ll really need Cygwin.  While installing, be sure to select the gnu tar package.  (Unless your backup contains Cygwin, you can just delete the c:\cygwin directory later to get rid of it all.)

Step 5: Unpack the tar file to the local drive

A prerequisite to this step is that you get access to the tar file created in step 1 — which you’ll have to wait for if it isn’t finished being built yet.  The simplest way to get access to the file is to map a drive to the *nix box that has the tar file. I mapped mine to the Z: drive, which was a pretty arbitrary choice.

Next, create a directory to put the recovered files into, because you do not want them going into the root directory yet.  I created a directory called “recovery.”  Launch Cygwin, then:

cd /cygdrive/c/recovery
tar -xvf /cygdrive/z/borkstation.tar

This part takes a while, but when it’s complete, the entire system as backed up will be in the c:\recovery directory.  N.B.:  this goes a little faster if you leave off the “v” parameter, but then you don’t see anything in the way of progress.  It also helps to occlude or minimize the cygwin window.

Step 6:  Rename and move files

There are three hardcoded paths in XP, that are probably the only folders in root on your minimal installation:  Program Files, Documents and Settings, and WINDOWS.  Within the c:\recovery directory, rename these to something else.  I chose “Program Files.recovery” and so on.

Once these three directories are renamed, cut and paste everything from c:\recovery to c:\.  There’s no need to replace any files in c:\, and there shouldn’t be any overlaps, so if Windows asks if you want to overwrite any files, say “no.”

Step 7:  Boot to Recovery Console and rename key folders

Here’s where Step 3 becomes pretty important.  Once you boot into Recovery Console, you’ll need to allow yourself to work in the root of the drive using the “set” command:

set AllowAllPaths = TRUE

Once that’s done, you can rename the three hardcoded directory paths, moving the originals out of the way for your recovered files.  For the sake of having a fallback position, I rename rather than delete them at this point:

ren "Program Files" "Program Files.delete"
ren "Program Files.recovery" "Program Files"
ren "Documents and Settings" "Documents and Settings.delete"
ren "Documents and Settings.recovery" "Documents and Settings"
ren WINDOWS WINDOWS.delete
ren WINDOWS.recovery WINDOWS

The suffix “.delete” has no inherent meaning, it just gets the folders out of the way and signals that I don’t need them any more.  Once this is done, and you’re sure there were no unfortunate typos, you can type “exit” to reboot to a recovered system.

Step 8:  Clean up

After rebooting, pretty much everything should be as it was, although you’ll have three extra directories with a “.deleted” suffix plus the cygwin directory to get rid of.  It may be necessary to take ownership and grant yourself permission to do so, but there’s really no reason not to wipe them all out, since your original folders and files should be intact.

While the “read only” flag has been preserved for recovered files, the “hidden” and “system” attributes have not.  For most files, this doesn’t seem to matter much, but the “desktop.ini” files that dot the drives can have weird side effects, like launching an editor upon boot and showing up.  It’s easy enough to fix from the command line:

cd \
attrib +h +s /s desktop.ini

This will grind away for a while, since it will reset all the desktop.ini files on the drive.  Once complete, you’re back to where you were upon your last backup.

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Hyper-V Serial Ports and Windows 2008

Unlike many other virtualization solutions, it’s not particularly easy to connect a Windows 2008 Hyper-V guest to its host serial ports.  Perversely, there are settings to connect the guest COM ports to “named pipes,” but there’s no way on the host to connect COM ports to named pipes.  (It appears that this option is used primarily for debugging programs, rather than for using actual serial ports — it doesn’t appear to have been intended to be used to provide actual serial port access from the guest.)

The Hyper-V Deployment guide contains little more than this:

“Note:  No access to a physical COM port is available from a virtual machine.”

What follows is a recipe to access the physical COM ports on the host from a guest using com0com, and its related utilities.  The idea is to make a COM port on the host available via TCP/IP, and then attach to it via the guest, then make this process automatic.

First, on the guest, you’ll need an appropriate version of hub4com, and the batch file bundled with it, com2tcp-rfc2217.bat.  Naturally, I’m running 64-bit Windows 2008, and there doesn’t appear to be a version compiled for 64-bit Windows, so I had to compile my own.  This can be kind of a pain, especially if you’re using Visual Studio Express, so you’re welcome to download my 64-bit hub2com binaries here.

My device is on COM3, and I can make it available on port 7000 using the following command line:

com2tcp-rfc2217 COM3 7000

This gives me a DOS Window that shows me what’s going on — this is handy for debugging, but hardly something I want to leave on my screen all the time.  The simplest solution is to create a launcher script:

Set objShell = CreateObject ("WScript.Shell")
objShell.Run "cmd /K CD C:\Program Files (x86)\com0com & com2tcp-rfc2217 COM3 7000", 0, false

This script effectively hides the program so that it can run in the background, so all that remains is to have it launch when the system starts.  That’s best accomplished using the registry to create a new “Expandable String Value” under “HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run”.  It doesn’t matter what the Name of the String Value is, but the Data should be the command line necessary to launch the script:

%WinDir%\system32\wscript "C:\Program Files (x86)\com0com\com3-listen.vbs"

When done this way, the port is made available whether or not anybody is actually logged into the machine.

The guest is only slightly trickier, requiring both com0com and hub2com binaries to be installed.  Since my guest is 32-bit Windows XP, I could use the precompiled “i386″ binaries directly from the c0m0com sourceforge page.

The com0com installer wants to create a null modem pair from “cnca0″ to “cncb0.”  You’ll need this pair of virtual devices, and you’ll want to turn on “baud rate emulation,” and rename one end like a regular COM port.    This can be accomplished from the com0com command line setup:

install EmuBR=yes EmuBR=yes
change CNCA0 PortName=COM3

Once the virtual port pair is available, one end can be connected to the host, using the hub2com batch file com2tcp-rfc2217:

com2tcp-rfc2217 \\.\CNCB0 host-hostname 7000

As before, this opens a DOS Window where you can see what’s going on.  At this point, COM3 on the guest is communicating directly with COM3 on the host.  As before, a small launcher script is created to hide this window:

Set objShell = CreateObject ("WScript.Shell")
objShell.Run "cmd /K CD C:\Program Files\com0com & com2tcp-rfc2217 \\.\CNCB0 skypiea 7000", 0, false

And, as before, a registry string is added to the guest to launch this automatically in its own “HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run” key.

%WinDir%\system32\wscript "C:\Program Files\com0com\com3-client.vbs"

Simple, eh?  Well, perhaps not, but once it’s set up, the guest Hyper-V machine can communicate via COM3.  Additional ports can be added in the same way.

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SIIG Cyber Serial under Windows 2008, or getting old drivers to work

I’m in the process of “upgrading” a server from Windows 2003 server to Windows 2008 server, and one of the things this server does is manage a few serial devices.  Therefore, it contains an old PCI serial board, but the manufacturer has since moved on to newer hardware, and hasn’t bothered to update the drivers.

Trying to install the Windows 2003 drivers yielded the following:

a service installation section in this inf is invalid

And, naturally, refused to install.  To track down the source of this error, there is a file created in \Windows\inf called “setupapi.dev” that logs details about the driver installation process.  Reading through this file, the reason for the error is evident:

inf:       ServiceBinary=C:\Windows\system32\DRIVERS\mf.sys  (mf.inf line 39)
!!!  dvi:       Add Service: Binary 'C:\Windows\system32\DRIVERS\mf.sys' for service 'mf' is not present.
!!!  inf:  {Install Inf Section [MFINSTALL.mf.Services] exit(0xe0000217)}

Intriguingly, a quick search through C:\Windows\System32\DriverStore\FileRepository showed that the driver does exist, it just happens not to be installed.  There’s a folder called mf.inf_Identifier (where “Identifier” appears to be random junk) that contains a file called mf.sys.  Copying this file into C:\Windows\System32\Drivers allowed the device drivers to install, and they appear to work perfectly well.

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