Restoring a backup that's way too large RRS feed

  • Question

  • I have been backing up my laptop continuously for a while now, and now comes the payoff -- I have a hard drive in the laptop that's failing and I'd like to restore my latest backup to a new drive in the same machine. When I boot from the restore CD and get to the screen where I choose which backup to restore, I choose the latest one, but then on the next screen I can't select the C Volume for restore to the new drive. The new drive is the identical make/model/size as the original (320GB), but WHS shows the size of the backup as 470GB, so I'm guessing it thinks the old drive was bigger. The old drive was not fully utilized (probably around 240GB), and I even excluded certain folders from the backup (like virtual machines and large videos), so as to not take up too much space on the home server, so I would estimate that the amount of space the backup should be occupying at no more than about 150GB. WHS show the size of every backup I've done for this laptop as the same - 470GB.

    Why is the backup so large? Is there a way to "shrink" it to the size of the current state of the machine so that I can proceed with the restore? Will a defrag/manual backup on the old drive help here? I'm loath to put the old drive under too much stress if it's about to fail...
    • Edited by wbradney Wednesday, March 3, 2010 6:18 PM
    Wednesday, March 3, 2010 12:16 PM

All replies

  • Hi,

    You can only restore a backup to a drive of the same size of larger. In your case it sounds like something has gone wrong with your backups and the drive size has increased - unless you are including an external drive in the total size (do you have a USB External Drive?).

    I would use the precious time you have left to attempt a disk image copy using something like gparted (free) or acronis (paid for).  You will need to be able to connect both drives at the same time.

    Good luck,
    Wednesday, March 3, 2010 1:19 PM
  • Did you use any advanced features like compression or encryption on the laptop drive?

    If you want a smaller backup, there are a couple of things you can do. If the drive in the laptop today is still functional, you may want to use the tools in Windows to shrink the primary partition, making for a smaller backup. Or you can get a larger hard drive for your laptop, or you can try restoring to a different drive, followed by cloning to the new drive for your laptop.

    In general, though, it's not possible to restore to a drive that's significantly smaller than the size Windows Home Server believes the original source drive to be. There are special cases where you can get down to slightly more than half the size, but on a drive that's been in use for any amount of time, that won't apply.

    I'm not on the WHS team, I just post a lot. :)
    Wednesday, March 3, 2010 3:37 PM
  • This laptop has never had any external hard drives attached to it -- maybe a USB thumb drive or two, but nothing that could have caused the backup to grow by 150GB.
    I already have a drive image of the failing drive, but I wanted to try WHS restore in this case because I'm relying on that for a number of machines where I don't want to have to manually go around imaging the drives -- that's one of the main reasons I bought a Windows Home Server.

    Ken, if I shrink the partition down to roughly the size of the data on the drive, and then do a manual backup to WHS, is that supposed to reduce the size of the backup as seen in the WHS console?

    Alternatively, I suppose I could change the name of the machine, re-install the WHS client software, and then add it to WHS as a new machine (as far as WHS is concerned). Then hopefully a single manual backup of that new client should be well below 320GB.
    Wednesday, March 3, 2010 6:15 PM
  • The source of the "requirement" that the disk you restore to be at least as large as the disk you backed up: Windows Home Server backs up every "used" cluster of data on the disk, along with information about where that cluster was. When you restore a backup, Windows Home Server needs to be able to put every cluster back where it came from. NTFS makes use of various portions of the disk for various things, and those portions of the disk can be scattered all over. As a result, even on a freshly installed operating system, somewhat over 1/2 the disk is seen as "used".

    As for shrinking the partition, it will hopefully reduce the size of the disk as seen by Windows Home Server to somewhere near the amount of space used. Then you can restore that to the full new disk. (Note: when you shrink the current partition you will have to reconfigure backups for that computer, because Windows Home Server recognizes the disk using a combination of several pieces of information, including disk size.) Effectively you'll be creating a "new" C: partition in the Windows Home Server backup set for that computer, one that's smaller than the current partition.

    You didn't answer my question regarding compression/encryption, by the way...

    I'm not on the WHS team, I just post a lot. :)
    Wednesday, March 3, 2010 7:33 PM
  • Thanks, Ken. I'll try to shrink the partition.
    I haven't used any drive-level encryption on the drive (I'm assuming you're refering to tools such as BitLocker).
    Thursday, March 4, 2010 1:39 AM