Friday, January 7, 2011

Windows 7: Notes on the System Imaging Feature

I decided to make a drive image using Window 7's system image feature. I had made an image previously, but System Recovery couldn't find it when I needed it.  As I was starting the system imaging process, I saw this warning:

Backing up to dynamic disk gives you limited functionality while performing system image restore.
I wondered whether my previous image would have been visible, when I tried to restore from it, if I had copied my Win7 image to a partition that was not on a hard drive containing any RAID arrays -- more specifically, to what Disk Management (diskmgmt.msc) would show as a "basic" rather than a "dynamic" drive.  I had originally saved the image to a basic drive, but had then moved them to a partition on a dynamic drive.  If I had originally tried to save it to the dynamic drive , maybe I would have gotten this "limited functionality" notification at that point.

My mission at this point was to see whether Win7's system imaging could do what Acronis True Image Home 2011 apparently could not.  Could it restore a bootable Windows 7 partition to a new drive C located on a RAID0 array?

I went into Control Panel > Backup and Restore > Recover system settings or your computer > Advanced recovery methods > Use a system image.  It gave me the option to create a backup now.  I took that, just in case.  I tried saving to a partition on the dynamic drive, just to see what would happen.  It did give me a warning, "The selected volume is on a dynamic disk."  I clicked on its "More information" link.  That opened this dialog:
Set up backup

When restoring a system image from this volume, the disks on your computer cannot be formatted to match the layout of the disks in the backup.  To have full restore functionality, select a volume on basic disk as your backup location.
It wasn't clear whether that meant that the very process of creating a backup on a dynamic drive would have this effect, or if they were just saying that trying to *restore* from a dynamic drive would be difficult.  I decided to save to the partition on the dynamic drive nonetheless.  But as I proceeded, it appeared that I was only setting up an ordinary backup.  The option wasn't available to "Include a system image of drives: PROGRAMS (C:)."  The explanation, which didn't entirely persuade me, was, "Because you are trying to restore your computer to a previous state, you can only back up data files" -- not program files, that is.

I canceled out of that and clicked Restart to continue the system recovery -- bearing in mind, here, that I was hoping to restore to the RAID0 array, which had not yet entered service, whereas this backup program was sounding like it intended to restore to (and overwrite) my current drive C.  I was actually willing to let it do that -- the system had been through a rough night -- but upon rebooting, it said, "Windows cannot find a system image on this computer."  It defaulted to the "Select a system image" option," so I went with that.  Then Advanced.  But still, we weren't able to find those images that I now had on two separate partitions.

So now I wondered if the failure to find my previous system images was due to the fact that I had changed their names.  I thought it made sense to do so.  They were all called WindowsImageBackup.  I changed them to put the date in front, e.g., 2011-01-07 WindowsImageBackup.  Maybe this kind of rigidity was calculated to make the program easy to use.  I suddenly realized that, contrary to my assumption, perhaps later backups would not overwrite the previous WindowsImageBackup folder.  I looked inside the WindowsImageBackup folder, and it did appear that images might be saved in subfolders with different dates in there.

So, OK, back in the partition on the dynamic drive, I changed the name of one of those folders back to plain old WindowsImageBackup.  It was still in a subfolder, not in the root folder.  I went again to Control Panel > Recover system settings or your computer > Advanced recovery methods > Use a system image you created earlier to recover your computer.  I skipped the backup step, this time, and clicked Restart.  The "scanning for system image disks" process still said, "Windows cannot find a system image on this computer."  I canceled that automatic search and again tried "Select a system image" and then Next.  Still no joy.

That was the story for the search for the WindowsImageBackup folder on the dynamic drive.  Back in Win7, I tried renaming the copy of the WindowsImageBackup folder that I had copied to the basic drive.  I went through the same steps again.  "Scanning for system image disks" and this time, praise Jesus and pass the tequila, we had a discovery!  We had liftoff!  We had a window that said, "Select a system image backup."  So the answer to this little mystery was that (a) you were not supposed to change the name of the WindowsImageBackup folder and (b) it had to be on a basic (i.e., not dynamic) drive.  Since this worked, I did not try the alternative of going into the WindowsImageBackup folder, in Win7, and just double-clicking on various files to see if they would spontaneously fire up and run the system recovery software.

So now that we had a system image ready to be restored, the question was whether it would insist on being restored only to the basic drive, or whether I would have an option to restore it to the RAID0 array I had set up to be my boot drive.  Actually, it did not say where it was going to restore.  It said that it was going to restore drive C, but it did not say where it believed drive C was located.  But surely it would not wipe out data partitions, at least.  I went ahead with it.  After five minutes or so, it said, "Restore completed successfully," and it rebooted back into Win7.  It had restored the image to the existing drive C, the one I had booted from.  So there did not appear to be an option to choose a different target drive.

So I now had restored my original hard drive to its original condition as of about midnight the previous evening, before things started getting funky.  Along the way, I had learned a bit about how Win7's system recovery feature functioned.

The remaining unknown was whether I could just munge my various copies of the WindowsImageBackup together into one.  Keeping backup copies, I went into Windows Explorer and did a simple copy-and-replace operation to combine those WindowsImageBackups, into one properly named WindowsImageBackup folder.  I didn't try to figure out which versions of the same file to keep; I just copied and replaced, more or less at random.

I left this combined WindowsImageBackup on the dynamic drive for the moment.  Then I went into System Image and let it do its reboot thing.  Its scan for system image disks failed to detect the ones on the dynamic drive.  So it seemed to be pretty much confirmed that it didn't want to save to, or restore from, dynamic drives.

I moved the WindowsImageBackup folder, containing the munged combination of two different backups, to the basic drive, and tried System Recovery again.  This time, it found the folder, but it detected only the older of the two backups within it.  So it seemed my file munging process had probably replaced the newer versions of some of the indexing files in that folder with older versions.  Apparently the imaging program looked at those small files when deciding which images were available.  I didn't test whether overwriting older indexing files with newer ones might have shown only the newer images.  Tentatively, it seemed that the best solution, when there were two distinct WindowsImageBackup folders, was just to keep them separate and eventually delete one of them, rather than try to combine them.



Thanks for an instructive article!

I was just trying the first step, doing a system image and got the warning when saving to a dynamic disk.
I'm interested in if you ever got your boot partition to you dynamic disk?
And will a system image from a boot partition on a dynamic disk be able to restore to a new blank disk?

Thats about where I stand today: I have my boot partition on a dynamic disk, and one disk is giving errors. But just replacing the bad one didn't work since the old disk have physical sector size of 512, and all new have 4096 (windows refuse to add mirror on disk with different physical sector size).

What I will test next is if a system image will be able to restore to a disk of different physical sector size.