What is the best way to update and keep folders in sync between two computers? For example, I work on my desktop computer while at home, but then on my laptop when travelling. I use a USB flash drive with all the folders I may need when away but each time before I go away, and then again upon my return, I have to update all my folders on the USB flash drive or on my computer. I don’t keep the folders on my laptop as that would be yet another update to complete, so instead I just access the files from the USB drive while travelling. As you can tell, this is quite a cumbersome and time consuming process so there must be a better way!

I am so glad that someone has asked this question, since this is something which I also grappled with over the past several years and have experimented with most solutions to this problem. You are correct that manually copying files between computers is not a good method to synchronise folders between two machines – this is a time consuming and also potentially dangerous process, as you may accidentally overwrite a file that you didn’t mean to overwrite and, in your situation, if you lose the USB drive or the data becomes corrupted you then will lose access to all of your data while you are away.

For the past few years I have had a need to keep data in sync between both my home computer and work computer so I found the easiest method was keeping three copies of my data – home computer, 2.5” USB external hard drive, and the work computer – and then use an automated utility to keep these copies always in synchronisation. Allow me to demonstrate this scenario through using an example. I keep all of my data that I wish to synchronise in one location – the My Documents folder. Initially I did a complete copy of the My Documents folder to all three destinations. This involved copying My Documents from my “master” computer (i.e. my home computer, which I knew had all the data I needed) to the external hard drive. I then copied the contents of the external hard drive to my work computer. At this point all three data sources (home, external drive, and work) have exactly the same copy of the My Documents data. Then I may modify some files on my home computer, together with adding and deleting other files. When I am done for the day I would connect the external hard drive to the computer and run a synchronisation utility (more about this later) which will synchronise the My Documents data on the external hard drive to be the same as my home computer. At this point the home computer and external hard drive have the same data. Then, when I went into work the next day, I would run the same utility again which would update the data on my work computer with the data on the external hard drive, bringing the data on the work computer into sync with the external hard drive and therefore the home computer as well. Now all three data sources have the same data. When I finish the day at work I would repeat the same process, in reverse, so that my home computer would eventually be updated with the data which I changed while at work.

This may seem like a complicated procedure, but it is actually quite simple and much easier than manually copying data (it is just fairly wordy to explain the process). Over the years I have tried various synchronisation utilities (both free and paid) but the best utility which I have found is ViceVersa Pro (www.tgrmn.com). In my experience this is a highly reliable utility which synchronises data very quickly and also can handle events such as conflicts (whereby both copies of the data have changed, for one reason or another) and will ask how you wish to handle and reconcile the conflict. A licence for ViceVersa Pro costs US$59.95 and there is a 30-day trial available on their website so you can test the software before purchasing. While this may seem like an expensive product in my experience it has been worth every dollar – the program is very customisable, to the point that I had it setup with the synchronisation configuration and then all that I needed to do was connect the external hard drive, click a shortcut to open ViceVersa Pro with my created configuration, and it would then proceed to automatically complete the synchronisation process (depending on the number and size of files which have changed it was pretty quick, generally finishing in under a minute if I had just changed Word documents and like).

ViceVersa Pro addresses the problem of synchronising data between two computers, but we now need to consider the security implications of the procedure which was previously outlined. As you can tell, you will potentially be carrying around a USB drive with all your important data. That means if you potentially lost the drive someone could gain access to this information for good or bad, so we need to take precautionary measures just in case the drive does get lost. The solution to this problem is encrypting the contents of the drive. Most people tend to think that encryption is a difficult process, but rest assured it is actually quite easy. There is a very good free, open-source utility called Truecrypt (www.truecrypt.org). This allows you to encrypt the contents of drives, including portable USB drives. Using Truecrypt you create a file on the portable USB drive which is the size of the encrypted volume that you wish to use. When you run Truecrypt to decrypt the volume it will ask for the passphrase that you set and then, assuming it is correct, decrypt the volume and mount it as a drive letter. You can then access the encrypted volume like any other drive on your computer. This would be the location in which you store all of your My Documents (or like) information, so that it can only be accessed once the volume has been decrypted. Of course, this means that you will always need to decrypt the volume before synchronising, otherwise the data on your USB drive will not be accessible, but that’s a small price to pay for complete data security. Just make sure you choose a complex passphrase to ensure that it cannot easily be broken. Furthermore, you may be interested to know that you can run Truecrypt in portable mode (www.truecrypt.org/docs/?s=truecrypt-portable) meaning that you don’t need to have Truecrypt installed on the destination computer where you wish to read the encrypted volume, but instead it can run directly from your drive. While this isn’t so much a concern in this situation, since you will need to install ViceVersa Pro on all computers to which you are synchronising, and therefore it’s not much effort to also install Truecrypt on those computers, this could prove useful for the situations where you may wish to read the USB drive on a different computer.

The procedure here is a quite secure and reliable method of synchronising files between computers. However, if you would like an even more hands-off solution then you may wish to consider some kind of online file storage. Probably the most widely known and used provider of online storage (also known as cloud-based storage) is Dropbox (www.dropbox.com). Services such as Dropbox monitor certain folders on your computer for changes and then synchronise the changes to your online storage area. Any other computers which are also linked to your account will automatically synchronise when they are online as well. As you can see, this is a bit like the manual method we discussed before except that the USB drive intermediary is actually online file storage, and the synchronisation happens automatically when you are connected to the internet and the file storage provider.

Of course, using an online storage provider requires the computer to be connected to the internet so that updates can be received and the synchronisation takes place. However, the utility which you install on your computer will usually cache all files on your computer (so that they don’t need to be downloaded on-demand) meaning that you can use the computer perfectly fine online, and it will synchronise next time you connect to the internet, which is particularly useful for laptops if you are using it on a plane, for example, without internet connectivity. However, you just need to make sure that you don’t edit other versions of the same files on other computers before the synchronisation takes place, otherwise you could end-up with a conflict if two files have been modified (since the system will not know which file is the most up-to-date copy).

That said, a concern that most people raise about online file storage is security. As you are essentially storing your data on someone else’s system there is potential for unauthorised access to data – which emphasises the particular need to ensure you have a secure username and password, since in the case of some services this is the only barrier standing between someone being able to access your data. There are many other services similar to Dropbox, such as JungleDisk and SpiderOak, with some others even offering the ability to define your own encryption key (so only you, with that encryption key, are able to decrypt your data – not even the online storage vendor theoretically can decrypt the information). However, the additional security of such services does come at a convenience cost – for example, using a Dropbox based service (which does encrypt your data on the server, but using a shared encryption key meaning that Dropbox does store the key and it’s not private to yourself) you can access all of your data though a web-based interface. However, if you use a service where you can define your own private encryption key this is not possible, as to decrypt the data the key needs to be stored on the server. That completely eliminates the benefit of having a privately defined key since the idea is that it is not stored on the server, but instead only on your local machine so the data is only encrypted and decrypted on the local computer and the key is never sent to the server where it could possibly be compromised. In reality, you need to make the assessment as to whether you need such additional security given the nature of data being stored. If you are just storing various documents then the convenience of a service such as Dropbox may be sufficient, although if you are storing more confidential data then due diligence may dictate that you need additional security.

Another consideration, depending on which devices you have, is that some cloud-based storage services even provide clients for mobile devices such as iPhone, iPad, and Android, meaning that you can access your data while on the move. This can be useful for some if you are not carrying your laptop but need to call-up a document at short-notice, as with an internet connection you are no longer limited to having the latest copy of that data synchronised on your device as (in theory) the latest copy of the files should be located in online storage.