Consider a disk with a single NTFS C: partition and Windows installed on it.

If I were to make a 7z archive of the partition, and grab the MBR via some tool (then store it in a file), would this be a complete backup of the disk?

By "complete backup", I'm asking if doing a backup in this manner, then restoring it later, would something break in a way that would render this way of making backups unusable as an alternative to something like Acronis or Symantec software.


7-Zip doesn't store NTFS security descriptors, for one thing. This can definitely break some applications (I have Cygwin in mind). I can't say for sure that it will "break" Windows itself, but it seems almost certain that some part of Windows will misbehave as a result.

  • Hm, this is for things such as user account permissions, correct? A quick Googling could not confirm or deny what you're saying, but it seems this util might just fix that problem... – Camilo Martin Jul 21 '12 at 8:29
  • Also, this might be a stupid question, but does Windows really care about file permissions? To me, the main reason for security issues in Windows is that everything (seems to be) "root" by default. – Camilo Martin Jul 21 '12 at 8:32
  • @CamiloMartin That was back in the Windows 98 days. 2000 and XP use ACLs (Access Control Lists). UAC in Vista and 7 is built completely around ACLs. I'm sure losing the ACLs would at least open some massive security holes, if not break the OS entirely. – Bob Jul 21 '12 at 8:36
  • @Bob Ah, but supposing the linked utility does backup security descriptors correctly, that would fill that (maybe last) hole, right? – Camilo Martin Jul 21 '12 at 8:52
  • I'll consider this answer correct, and if it is I'm ok with the implications of another file in the backup process. – Camilo Martin Jul 21 '12 at 9:22

This might work, but please test it first in a safe environment. (E.g. make a VM and test it with that).

Personally I used the dd (from a second installed OS) method before. You can compress the resulting image, or just pipe the output though gzip. It works. It is safe. It is universal (which is a nice thing when you want to restore). ... As long as you restore it to the same disk. Restoring such a backup to a smaller drive does not work. Restoring it to a larger drive works but does not use the extra space.

If you would want the latter then I recommend looking at software such as:

Trying to do the same work manually as these dedicated programs do is reinventing the wheel.

Having said that: It could be fun as an academic exercise. And you would learn things from it (such as the file descriptors being used and not being backed up). Just be prepared to need a few tries before it all works and make known good backups first.

  • I considered dd (or any other sector backup), but the problem is that the resulting archive is just as obscure as a proprietary format (I can't easily check the contents as I can with 7-zip), the compression is not as good (a dd.lzma vs. a 7z, because of file sorting by extension and no fragmentation), and last but not least, I might want to extract the contents to a resized partition. Acronis software didn't play nicely in the past with me and I didn't try Symantec but it's user interface looks so lackluster I'm reluctant. I didn't try FOG, but it looks server-oriented. – Camilo Martin Jul 21 '12 at 9:20
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    dd: (and other raw format disk images) can be mounted via the loopback device. Accessing the data should not be a problem - Acronis/ghost: In the past I made images for Dell lattitude laptops. Some of these would not work with ghost, some would not work with Acronis (but each would work with the other). Which is a long way to say that your milage may vary. Personally I preferred ghost 8.3 since it was nice and basic and for my feeling clean. – Hennes Jul 21 '12 at 9:27
  • You seem to have more experience than I do and it doesn't look like Acronis or Ghost are all that great - and dd has the aforementioned limitations. In my lookout, however, it looks like WinRAR can be a better candidate than 7z for a number of reasons... – Camilo Martin Jul 21 '12 at 10:13

No. Doing something like that is not a complete backup.

Just copying the Master Boot Record (MBR) is pointless (assuming you even could). Please read more about it and maybe you will see why:


Now, as far as archiving your running Windows system goes with 7z, again it probably won't work. Microsoft's DRM technologies alone will probably prevent you from restoring. There's also the problem of open (running) programs that will almost certainly cause problems with 7z. Then again, maybe you could archive a complete Windows installation if you did it from another computer - just not that computer. And even if you did I'm sure there will still be something that didn't get included such as hidden and/or system files. So hopefully, you know how to deal with file attributes. I also hope I don't have to go into file/folder ownership properties since that's yet another problem.

So to do a complete backup like what it seems you want to do you'd have to "image" the hard drive or at least image the one active partition that has your Windows OS on it. You'd also pretty much have to perform any imaging like that from another system too (ie. use dd from a Linux live CD, or possibly something that may have come on a bootable CD with your hard drive, or possibly something else from OnTrack perhaps).

Please don't get confused when it comes to Microsoft's "backup" utility too! I believe Microsoft lets you do something called a backup but it's not a "complete" backup since all you're really saving is your data and possibly any activation info. Therefore, in a complete restoration scenario you still have to reinstall (or restore) Windows. And then you will probably want to restore all your data which is the whole point of backing up.

So again, if you want to make a "real" backup of your entire Windows OS with all your data and everything so that you can restore it quickly in the event of a complete hard drive failure, you probably should be looking into "imaging" your hard drive or at least imaging the Windows partition. You might also like to look into RAID too but that's a whole other sack of worms.

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    > Please read more about it and maybe you will see why Please tell us why. It's good to have sources, but please include the information within the answer, perhaps a concise summary, if possible. – Bob Jul 21 '12 at 8:38
  • Wait a minute... the MBR can be backed up. Not only via Linux, but even via Windows on a PE with tools. Also, I never said I would do it in my running Windows, that just wouldn't work. Further, 7-zip can work perfectly in Linux. Further, 7-zip can read hidden/system files... there's nothing special with them... – Camilo Martin Jul 21 '12 at 8:48
  • Also, what I'm trying to know is what else could a (for example) .tib archive have that couldn't be achieved with a .7z one, a 512-byte file with the MBR, and it seems from jjlin's answer, a file with security descriptors. If there is something you know of, please tell me. Again, assuming no RAID, just a simple disk setup. – Camilo Martin Jul 21 '12 at 8:53

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