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It's quite possible to backup multiple machines to a single external hard drive. I'll review two approaches: the annoying, yet easy way and the right way.

I have two laptops and three PCs: two Windows 7, two Vista, and one Vista Pro 64 bit. I want to back up all of them on one two-terabyte external hard drive. Can this be done and how should I go about it? The external drive is not a network type: it's a USB drive.


I'll look at two approaches: one that's very inconvenient, but most likely to work on every machine, and another that's more complex to set up, but requires almost no intervention once in place.

Planning for Multi-Machine Backups

We're going to want to keep things straight on the external hard drive, so I'm going to suggest that we organize things into folders. In fact, I'm going to suggest that we segregate backups into their own folder, as you may find yourself using this drive for other things as well.

So, step one, create a top-level folder called "backups":

Backup Drive in Internet Explorer

Step two, inside that folder, create a sub-folder for each machine:

Backup Drive with sub-folders in Internet Explorer

This will allow us to keep the backups from the different machines separate and organized.

The Low Tech Solution

This solution is inconvenient, but it maximizes the probability of success and the speed of each individual backup.

Ready? Here it goes: Take the drive from machine to machine.

This sounds horrible, I know, but sometimes, low tech can be the most practical answer.

"Two terabytes seems like a lot right now ..."

On each machine, configure the backup software you're using to place backups into the folder we created for that individual machine. Then, when you attach the drive to each machine and perform the backup manually, they'll remain well-organized and not interfere with each other.

And yes, I did say manually. Unfortunately, manually moving the drive from machine to machine does mean you're not going to be able to schedule the backups to happen automatically.

The Networked Solution

This is perhaps the ideal solution, but it relies on a few things:

  • Your computers are networked together.

  • They can "see" each other on that network.

  • The backup software you're using will allow you to backup to a network resource.

  • The backups don't take "too long", which I'll talk about in a moment.

Setting up a Windows network, particularly when Windows 7 is involved, is beyond the scope of this article, so I'll simply have to assume that you have one and that it's working well.

The first step is to pick one machine to which you'll attach your external drive. This machine would be on most of the time and must be on at times when the other machines might want to back up.

Share the drive. Right-click on the drive in Windows Explorer, and click on Share With... and then Advanced Sharing..., and in the resulting dialog, click on the Advanced Sharing button to get the Advanced Sharing dialog.

Advanced Sharing Dialog

Check "Share this folder" (as we clicked on the drive we're actually sharing the entire drive).

The share name defaults to the drive letter, which I've left alone in the example above. I also added a comment describing the drive being shared.

Click on the Permissions button.

Permissions for sharing dialog

For the Group name Everyone, make sure that Full Control, Change and Read all have Allow checked.

To be clear: this means that any machine on your local network will have full access to this drive. It's still protected by the security software on the machine it's connected to, and it's still behind the routers firewall so it's inaccessible from the internet. But it's important to know that any machine on your local network will have complete access to read and write to this drive.

Which, as it turns out, is what we need for our backup solution.

On the machine that the drive is connected to, configure your backup as you wish, but make sure to have it place the backup on the external drive and in the appropriate folder. For my example, I might configure it to use "I:\backups\Machine1" as the backup storage location.

For each of the other machines on your network, you can also configure the backups as you wish, but make sure to configure the backup storage location to be on the shared drive. In my case, the specification might be:


Where HostMachine is the name of the machine to which the drive is connected, I is the name we assigned the shared drive (remember, I left it to be the drive letter), backups is the top level folder into which we're placing all backups, and Machine2 is the folder I've designated for the backups from this machine. Use a different folder name for each machine.

Aside from Windows networking, the only real issue with this setup is speed. Your network is probably slower than your external hard drive, and depending on how much data you're going to be backing up each day, the backups could take a little while. You'll want to avoid congestion by scheduling the different backups to happen at different times to make things as smooth as possible.

A Word on Growth

Two terabytes seems like a lot right now, but you're already planning to share that across five machines. Depending exactly on what you're backing up and how you have it configured, I could see you eventually running out of space.

The good news here is that this network-based technique can be split: get a second drive and have the machines backup to it on one machine and then have the remaining two machines backup to the original.

Taken to the logical conclusion, of course, that would eventually have you putting an external drive on each machine.

Which, in all honesty, could be the best solution in the long run anyway.

Article C4738 - February 10, 2011 « »

Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

Not what you needed?

Ken B
February 11, 2011 6:12 AM

A couple of things to add...

My own personal preference would be to not share the root directory of the share drive, but rather share the "backups" directory with the name "backups". Among other things, it segregates the directory into it's own share name, and "hides" whatever else might be on that drive. (Or, perhaps, password protects other shares on it.)

Next, there are external drives that can be attached directly to the network, and appear as their own file server. While more expensive than a simple USB attached external drive, they are typically faster (running at network speed, not USB speed), and don't require a host computer to be attached to. (Your readers can search for "NAS" or "network attached storage".)

Finally, a middle-of-the-road solution are networked USB hubs. They connect directly to your network, and any USB devices you attach to it can be used just like a locally-attached USB device. The downside (at least on the one we have) is that only one computer can be attached to a given device at any given time, so you would need to tell the software to connect to the device, do your backup, and then disconnect. However, you don't need to physically move the drive from computer to computer. (We use them for printers, since the driver can automatically connect/disconnect when there is something to print.)

Randy G
February 15, 2011 4:38 PM

Hi Leo,
I've used the set up just as you described for backing up, but when I tried to restore a PC using the image stored on a remote PC's USB external drive - it wouldn't work. Even though I was able to browse to the external image and Acronis recognized it and went through it's process only to reboot and come back without doing anything. When I removed the external USB HD & connected it locally to the PC being imaged - it worked fine. Note all the back ups were carried out over the same LAN without a problem, it just wouldn't restore over the LAN as I suspected it should. Am I wrong to assume you can restore a PC over the LAN with Acronis TIH 10 or is this a setting in my router? I have everyone sharing the backup image. Thanks, R..

While I'd expect it to work as you expected it to, I can't say that I'm surprised that it didn't. Personally at the time of a restore I probably wouldn't want to rely on a network anyway and would do as you ended up doing: attaching the backuip drive directly to the machine being restored.

May 24, 2011 6:08 AM

Does this folder segregation work for backups from the same computer (instead of being over written)? I tried today to backup Win 7 (gave up on XP the few times I tried). I think things have gone haywire and want to save the next backup (including system image) seperately - it may work differently or be worse than what I already have managed to save (even though it says never done when I went back into 'Back up your computer'. also
I can't understand the above instructions how to do it i.e. "create a top-level folder called backups" - - - where, how?

thanks for your help.

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