Why you Should Not Rely on a Disk Clone as a Backup

Dennis Faas's picture

Infopackets Reader 'Mike' writes:

" Dear Dennis,

[Regarding your post about the TorrentLocker Ransomware virus, I would like to hire you to help me set up a backup on my system to help keep me protected against such threats. As for my question, I have a Windows 7 Lenovo desktop with a 1 TB internal hard drive] ... I want to clone my internal hard drive to an external hard drive, maybe once a week. I then want to reverse clone the hard drives [in case I get hit with a virus like TorrentLocker] ... It seems intuitive that [when I clone the hard drive for backup, that] both hard drives should be the same size. Fry's electronics has a 1TB Buffalo HD on sale for $59. [What do you think? Also, Amazon has a similar hard drive for around the same price] ... If you agree, I'll order one from Amazon (using the Amazon URL that pays you a small amount). "

My Response:

Thanks for your email and the offer to use Amazon to help fund our site.

You suggest cloning your hard drive once a week as a way to protect your data against encryption viruses and similar threats; I'm afraid that this would make for a very poor backup strategy. I will explain that more in detail, but there are also a few other things to consider before I dive into that.

External Backups: Does your Computer have USB 3.0?

First, in regard to purchasing an external hard drive with USB 3.0 functionality: please check if your computer has a USB 3.0 connection, as it will make a huge difference in terms of the time it takes to backup and restore. If it does not have the USB 3.0 connection, then the drive will default to USB 2.0 which is much slower. USB 3.0 is identifiable by the blue plastic inside the USB female connection on the computer. If your system does not have USB 3.0, you can purchase an internal USB 3.0 PCI express card so you can use USB 3.0 with the external hard drive as its full speed. Note that USB hard drive speed comparisons are approximately 27MB/sec for USB 2.0, versus 80 to 120MB/sec with USB 3.0. That might not sound like a big deal, but when you're transferring large amounts of data as with backups, it's a big deal.

Differences in Hard Drive Prices and Size can be Nominal

Secondly, the price difference between a 1TB and a 2TB hard drive might be $20 or $30 or so, and in such a case, it makes more sense to get a 2TB model at that price point. Hard drive prices change all the time depending on what is available on the market. Right now 4TB hard drives are the norm, so the price difference between a 1TB and 2TB would be nominal as there is less demand for these units. So, please take the time to shop around and compare different models.

Compare Reviews on Various Hard Drive Brands

Thirdly, I don't have any experience with Buffalo products -- and that's not to say that they aren't any good -- but, you could probably just as easily get a Western Digital or Seagate external unit for around the same price. Buffalo in all likelihood uses the same hard drive produced by big name tech companies (like Seagate, Hitatchi, etc), but the biggest difference will be the interface (chipset) inside the unit, and it can be quirky if you go with lesser known brands. My recommendation therefore is the Western Digital 2TB external 2.5 inch USB 3.0 hard drive; I own two of these drives and they perform very solid. Please note that whenever I shop for a product online Amazon.com, I always look to see how many product reviews there are, and what the product is rated. That said, Western Digital and Seagate external hard drives are top sellers whereas Buffalo is not.

Scheduling Image Backups Versus a Drive Clone

The most important point to all of this, however, is your backup strategy. You suggest creating a full clone of your hard drive once a week as a way to protect your data against encryption viruses and similar threats. As I stated earlier, this is a poor backup strategy. Technology corporations certainly wouldn't rely on this as their sole strategy, and you shouldn't either.

Instead, I recommend that you create a rotating schedule using disk image backup sets (for example: once a month, once a week, and 3 time as week). That way, if you ever get hit with an encryption virus (or any virus / malware for that matter) AND the virus ends up getting saved into your backup AND the virus is retroactive after you restored it -- you will have a much better chance to undo the damage using an older / later backup that might not have the virus in it.

Also, if your latest disk image backup set fails for some reason, you will have other backup sets to try if you schedule them regularly. Thus, a 2TB external hard drive compared to a 1TB external hard drive would be a much better option rather than a single clone of your hard drive, plus it will provide you with much better redundancy.

Difference between Drive Clone and Image Backup Sets

There is a huge difference between a 1-off hard drive clone compared to a disk image backup set. A full clone of the drive will mirror your existing drive as it is and eat up the entire destination / backup drive (assuming source and destination drives are the same size). Instead of doing that, a disk image backup set would save the image of the source drive into files on the destination drive; oftentimes, compression is used to save space -- usually by 50%. From the disk image set, you can restore a full clone of your hard drive. This will effectively give you the exact same result as if you did 1-off full drive clone, except you used disk image files instead as the source. If you are new to disk imaging, then this needs to be taken into account -- cloning the drive in full is just one option, but image backup sets are a much better way to go. Backup sets also provide you with many other options, including incremental and differential options that will save you oodles of space on the backup unit, and also take considerably less time to backup.

PS: I do appreciate you ordering through Amazon using our link.


If anyone reading this article found this information useful, please consider donating to the site. You can also hire me to help you with your backup strategy.

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About the author: Dennis Faas is the owner and operator of Infopackets.com. With over 30 years of computing experience, Dennis' areas of expertise are a broad range and include PC hardware, Microsoft Windows, Linux, network administration, and virtualization. Dennis holds a Bachelors degree in Computer Science (1999) and has authored 6 books on the topics of MS Windows and PC Security. If you like the advice you received on this page, please up-vote / Like this page and share it with friends. For technical support inquiries, Dennis can be reached via Live chat online this site using the Zopim Chat service (currently located at the bottom left of the screen); optionally, you can contact Dennis through the website contact form.

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kitty_zoso's picture

I like the idea of multiple regular image backups, but what if the problem isn't virus or software related, it's a hardware system failure? You usually can't restore an image to different hardware, can you? For instance, your old laptop has a catastrophic motherboard failure, and now you want to get your stuff working on a new laptop almost always a different, newer model. Would the image backup be incompatible with the new hardware or corrupt the new system's fresh operating system?

Dennis Faas's picture

Yes, it's possible and I have done it. That said, restoration to different hardware may not work and depends largely on which hard drive controller was used during the original installation (example: AHCI, SATA, IDE, UEFI, RAID, etc). Also, if you use another motherboard, you will have to re-register Windows again as this would void your license from the previous installation. Another option would be to virtualize the existing machine which would be hardware independent, but I don't know of any scripts that would do that on a regular basis.

Stuart Berg's picture

I don't know about other backup software, but Acronis True Image software has a capability called "restore to dissimilar hardware" (https://kb.acronis.com/content/47606) which does as the name implies. That's just one of the reasons that I like the Acronis backup software.

Doccus's picture

I have a disc clone backup.. although a virus or bot is uncommon ,in my case, hard drive errors are quite frequent on OSX (I am using a 2010 imMac with10.6.8, 10,7 , and also 10.10. In any case, the solution I use would also prevent a dormant virus fropm activting as well.
The Initial disc clone took some time, being half a TB, but the updates take less than 5 minutes. To avoid carrying over "sleeping malware", as Dennis says, I act as if I might have them, wih backups no more often than a month, or even less if little activity occurs on your machine.. Instead of frequent backups, I focus in on the folders that have seen the most activity, such as the "documents", or , in my case especially, "scans and pictures", or movies, etc.. whatever it might be, and duplicate them to a safe place. You can create a folder for that specific purpose, and simply use your cloning software to update the contents of the folder, and scan for malware. Or just leave it be as a duplicate dated copy, if you have the room, kind of like "time machine" does.
This has proven to be the most effective soluition for me, in part because I may have a lemon iMac, I have been subject to system crashes from the day it was new, and resolution weirdness as well. The worst , though, are the system freezes requiring hard resets. Very un-Maclike. And can cause hard drives to go bad. THat's when a complete up-to-date system clone is worth it's weight in gold ;-)

tmcd's picture

Some imaging software, such as Macrium Reflect which I use, offer you the option of also mounting the backup set and restoring individual files and folders in addition to the entire image. If you have to replace your hardware this is a good option in case a "bare metal" restore is not possible.

RedDawg's picture

Just for another opinion. (All updates are to external drives)

1) When I first setup a new system, after all needed software for that system is installed and configured; I do a complete system backup called base-setup. This backup is NEVER deleted.

2) Every time new software is installed or anything from Microsoft monthly updates to any software update is installed A new update is created to a different folder, the (old update) backup is deleted. this leaves 2 updates that can be used if necessary.

3) Every day all data folders are updated at the end of the day.

4) these are ALWAYS removed from the physical location, and copied to our private NAS mass storage. At this point I copy them to a third location.

It does use a lot storage I admit. I have NEVER had a crash, or infected machine, (including servers) I could not have back up and operational in a matter of hours.

Using this form of backup it is imperative that data folder backups be done daily! This can be done one of two ways. Backup software, or Sync software (obviously I will not be syncing a server LOL). A laptop or desktop can start a sync just before the end of the work day and is ready to go when the office closes. Servers are in a different location and I handle those myself.

Someone only worried about a home desktop and/or a laptop could easily adjust those steps to fit the required machine or machines.

If you are using a third-party backup solution, no problem just schedule your backups to fit your usage pattern.

Just my 2 cents worth for something that has worked very well for me for many years.