Auto backup of files

August 22, 2009 8:57 AM

I have two computers, one Windows, one Linux. How can I make it so they synchronize automatically with each other, as in, I update the file on one computer, and the updated file gets put onto the other? Networking? Using an external hard drive? What software might be useful? Bonus points for free software
posted by gilsonal to computers & internet (13 comments total)

Dropbox will do that... available on Windows, Mac and Linux!

http://www.getdropbox.com/
posted by mattdini at 9:08 AM on August 22

Unison, rsync, ssh, etc. plus cron. You might also use version control software for work files.

You obviously don't just synchronize root directories. But you can share the drives using samba and smbmount, for when some important file exists outside the synchronized directories.
posted by jeffburdges at 9:09 AM on August 22 [2 favorites]

Just fyi, Dropbox isn't suitable for files that need security, like stuff under NDAs, bank account information, etc. But yes Dropbox is quite painless if you don't need security.
posted by jeffburdges at 9:11 AM on August 22

Seconding dropbox, it's really easy and also works as an online backup.
posted by kylej at 9:14 AM on August 22

Definitely Dropbox.

It does cost for more than 2 GB though, but the service works exactly as advertised.
posted by photomusic86 at 9:20 AM on August 22

jeffburdges: "Just fyi, Dropbox isn't suitable for files that need security, like stuff under NDAs, bank account information, etc. But yes Dropbox is quite painless if you don't need security."

Stuff like that shouldn't ever be stored unencrypted anyway and, naturally, Dropbox works fine with encrypted data.
posted by turkeyphant at 10:18 AM on August 22

It would be helpful if you could provide more detail on what you need to share: how many files, how frequently they need to be synced, etc. For local sharing, I don't think Dropbox is a good solution - it's silly to sync your files locally by pushing them up to the cloud and then pulling them back down, although it does get points for ease-of-use.

I don't do a lot of syncing between my computers, but I do keep my music collection updated across all of them. For that, I run Samba on the Linux box and use SyncToy on my Windows machine to update the files on the shared drive.
posted by sinfony at 10:20 AM on August 22

Assuming they're in the same house, I'd argue that you should pick the computer with the bigger hard drive, put all the important data on there, and share the relevant folders over the network. Samba sharing works fine for this.

It's easy, it doesn't require any third-party software, and it's secure since your router is firewalling you from the outside world.
posted by chrisamiller at 10:26 AM on August 22

Are they both at home? There's really no need for file synchronization — just create a shared volume on one computer and mount it on the other so that you'll be accessing the same files on each. It's really the simplest way to do it and is as simple as setting up a Samba share. If one is a laptop that you'll take out and about, Dropbox would be ideal since you don't need to be on the same LAN for it to work. If you can want to do a differential backup and resync of a folder, rsync can help with that and it's built into Linux and OS X.
posted by cgomez at 10:47 AM on August 22

I'd use Unison.
posted by PueExMachina at 7:23 PM on August 22

turkeyphant : You will lose most advantages of dropbox, and fill up your quota faster, if you use encryption. I'm sure dropbox is fine for your bank account details, if they are encrypted. But you might be violating an NDA for even posting covered files when encrypted. You must also check if the encryption software writes temp files into the current directory!
posted by jeffburdges at 9:00 AM on August 23

jeffburdges: "turkeyphant : You will lose most advantages of dropbox, and fill up your quota faster, if you use encryption. I'm sure dropbox is fine for your bank account details, if they are encrypted. But you might be violating an NDA for even posting covered files when encrypted. You must also check if the encryption software writes temp files into the current directory!"

I don't understand your comment. What advantages would you lose and how would you fill up your quota any quicker? In any case, only the sensitive data need be encrypted and no decent encryption software (e.g. Truecrypt) would leave insecure traces in the synced directory. I know nothing about the legalities of NDAs but I'd be shocked and amazed if using Dropbox would have any impact at all.
posted by turkeyphant at 10:36 AM on August 23

You cannot usually save space by storing only deltas of encrypted or compressed files, which is obviously how dropbox works.

I'm fairly sure their free 2 gig quota isn't just "2 gigs current" but "2 gigs current plus history deltas" and they throw away old deltas, i.e. if you put 2 gigs on then you'll have no history. If you encrypt or compress a 1 meg file, then any delta may require the full 1 meg, meaning you burn another 1 meg every time you modify that file. You might not notice this since old versions will eventually get deleted, but it'll happen.

Encryption software may normally write temp files into the working directory, so long as they are later removed. I myself use effectively "gpg --decrypt $f.gpg > $f && vi $temp && gpg --encrypt $f && rm $f". But dropbox makes writing this temp file $f insecure, even for only milliseconds. You may always make this secure by writing temp files into /tmp, but not everyone does this.

I imagine truecrypt would store an entire volume in one file in your dropbox, which surely makes dropboxes history rapidly useless. You might also check your network bandwidth consumption when using truecrypt & dropbox together. I doubt however that truecrypt writes temp files, so your likely still secure, just giving up your physical layer of security.

I'm sure dropbox is fine for an encrypted file containing credit card numbers, a teachers exams, website passwords, etc., but just don't touch it if industrial espionage could cost your employer hundreds of thousands.
posted by jeffburdges at 5:11 AM on August 26