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September 7, 2005 5:40 PM

Best way to backup two OS X laptops to a single firewire drive?

My wife and I each own iBooks, and we've recently purchased a firewire external hard drive with enough capacity to hold the entirety of both of our hard drives. I'm wondering what's the easiest way to back up our laptops regularly?

I have downloaded Carbon Copy Cloner, a trial version of SuperDuper, and Lacie's Silver Keeper, but all of them seem to want to make the external drive a clone of my hard drive, which would prevent my wife from using it too. I haven't tried Personal Backup, or Retrospect, both of which look promising, but expensive.

Does anyone have any experience with this? Perhaps I should just copy the /applications and /users folder to the hard drive manually once in a while?

Bonus points if you can propose a solution which only does versioning like my SVN server at work, so that I can roll my machine back to a specific date.

Double Super Bonus points if you can propose a solution which keeps my wife's and my archive protected with separate passwords (not that either of us have anything to hide from eachother, but we may share this drive with others).

posted by Popular Ethics to computers & internet (16 comments total)

Why not just set up an SVN repository on there, then? It's remarkably simple on OS X.
posted by zerolives at 5:45 PM on September 7, 2005

zerolives: Why not just set up an SVN repository on there, then? It's remarkably simple on OS X.

I wondered about that. But I was under the impression that SVN requires a server to be running, and I'm not sure I know how to get such a server to work with an external drive that may or may not be connected. Also, I'm not sure if SVN takes care of all the little macintosh file goodies like extended attributes and resource forks.
posted by Popular Ethics at 5:55 PM on September 7, 2005

Perhaps partitioning the drive would be a solution? I haven't tried it in OSX, but if the backup software sees the firewire drive as two seperate drives, it might solve your problem.
posted by stet at 6:01 PM on September 7, 2005

Retrospect is indeed what you want. You can actually just install Retrospect on one of the machines and the network client on the other, and back up the second machine over the network -- this way you won't even have to hook up the second machine to an external drive.

Retrospect gives you the option of copying the files and folders (in which case the backup is Finder-browseable, which is nice, but you only get to keep one copy of each file) or creating backup sets (which basically cram all your backed-up files into one file, which can be compressed and can include multiple versions of each file -- of course you can only restore from these using Retrospect). You can also backup to CD/DVD or tape in addition to hard disk.

Retrospect can be somewhat of a bear to configure because it is so flexible, but once you get it set up, you'll wonder how you ever got along without it. It can even wake up your machine in the middle of the night to run your backup.

Buy.com has Retrospect Desktop for $86.99 with free shipping (no sales tax outside CA), plus you can get a 2% ebate on top of that. If you're not an ebates.com member you can get a $5 bonus for signing up, which brings your total price to $80.25.

Partitioning the drive will work, but it gives each of you only a fixed amount of space, which might suck eventually if you end up creating different amounts of data.
posted by kindall at 6:12 PM on September 7, 2005

I've used Lacie's SilverKeeper, and it will let you set a specific folder that your backups are filed under (click Destination, navigate to your backup folder on the external drive). You and your wife could each create your own folder, and tell SilverKeeper to backup to your personal folder. SilverKeeper can save that setting, too, so you don't have to remember to set up the destination folder each time.

As for password-protecting the backups, each of your home directories would still be "owned" by the user account that they belong to (unless you turn off ownership for the drive, which can be toggled on the Get Info panel for the drive). For example, on my backup drive, when logged on as myself, I can get into everything under Users/katie, but I can't get into the folders in Users/boyfriend. Depending on exactly which files you want to keep private, this might be enough. (Although I don't know if this would still work with multiple computers backing up to the drive.)
posted by katieinshoes at 6:17 PM on September 7, 2005

Here is how to do it with two seperate passwords... using only the (awesome) backup tools that came with OS X.

1) Open /Applications/Disk Utility
2) Click New Image, and create two appropriately-sized images on your firewire drive, using AES-128 bit encryption. One will be for your backup, and the other for your wife. Mount the images.
3) Use rsync from the command-line to backup your files. The -E flag copies resource forks.

rsync -avE /Users/PopularEthics /Volumes/PopularBackup
rsync -avE /Users/Wife /Volumes/WifeBackup

Type "man rsync" for more info on how to use rsync. You can also download the free GUI RsyncX if you don't like command lines.
posted by rajbot at 7:25 PM on September 7, 2005

Bonus points if you can propose a solution which only does versioning like my SVN server at work, so that I can roll my machine back to a specific date.

Sorry, I forgot to include this part. Use rsync with the --backup and --backup-dir options for this.

rsync -avE --backup --backup-dir="/Volumes/PopularBackup/2005_Sept_7/" /Users/PopularEthics/ /Volumes/PopularBackup
posted by rajbot at 7:33 PM on September 7, 2005

Carbon Copy Cloner can make disk images of your drive. Check out its preferences for a bunch of options.
posted by hyperizer at 7:51 PM on September 7, 2005

Sorry, a better command-line would be
rsync -avE --backup --backup-dir="/Volumes/PopularBackup/OldVersions/2005_Sept_7/" /Users/PopularEthics /Volumes/PopularBackup

Note that /Volumes/PopularBackup is the mount name for PopularBackup.dmg, which you created in Step 2, above. The backup is encrypted using 128bit AES, and you need a password to mount it.
posted by rajbot at 7:59 PM on September 7, 2005

rajbot, hyperizer: Thanks, I didn't consider making a disk image. (I always thought mounting a .dmg copied its contents to the local drive first!) The unix is a bit dense, and I'd prefer a nice gui like CCC, but you've given me a path to look down...

Some follow up questions then: Lets say my internal hard drive crashes. How do I boot from the .dmg file on the external?

If I understand correctly, since rsync copies only the diffs of files that have actually changed, your suggestions would recopy the entire hard drive for every dated folder. If true, that would fill up the external after only a few backups each. Have I misunderstood?

I'd really like something like SVN which (as I understand) keeps a running tally of the diffs, so you can roll back to a specific version.
posted by Popular Ethics at 8:50 PM on September 7, 2005

How do I boot from the .dmg file on the external?

You can't boot disk images. Just install a system on the external drive (outside an image) and install a copy of your backup software and a few other vital utilities (e.g. DiskWarrior) there. Then you'll be able to boot that disk and do maintenance on your primary drive and restore files to it.
posted by kindall at 9:44 PM on September 7, 2005

If true, that would fill up the external after only a few backups each. Have I misunderstood?

Yeah, I think so. But the more I think about it, the more it sounds like you should be running a svn server on your local machine and storing your repository on an encrypted disc image. However, I will continue to babble about rsync, in order to answer your question.

Rsync in archive mode (with -a) makes exact, synchronous backups. So if you have a 1GB drive you want to back up, rsync -a will copy exactly 1GB to your disk image. If you add a 1KB file, then then next time you run rsync -a, it will copy only that 1KB file over to your disk image.

If you use rsync -a, your backup will never exceed the size of your original volume.

Data expansion only happens when you want to keep the changed versions (the diffs). That is what the --backup option does. Let's say you run rsync a first time, change a 1KB file, and then run rsync again (with --backup). Rsync will make an exact copy of your original volume to your disk image by only copying over that changed file, and will copy the old version of that file to the directory specified by --backup-dir. Which means if your original volume was 1GB, your disk image now has 1GB in the backup folder, plus an additional 1KB in the dated old versions folder. (Yup, it re-copies the entire 1KB file, not just the svn-type diffs.)

I'm sorry for cluttering up this thread with my posts. I've used every backup software solution on the market, and have been burned by them all. Rsync is the only thing that I trust, but it takes several posts to explain how to use it :)
posted by rajbot at 11:34 PM on September 7, 2005

Backing up is only half the issue here. In my experience, it's worth spending a bit of money to get a system that allows for a nice easy restoration of data. You can do backups for free using rsync, but restoring data is a little fiddly, and it's not quite as easy to pull a file out from anything other than the most recent backup.

At the end of the day, your time is the most valuable asset you have, so it's up to you wether or not you would spend many hours wrangling with some rsync'd folders trying to restore data, or just clicking a button in Retrospect, but paying $90 for the privilege.
posted by gaby at 1:24 AM on September 8, 2005

Backing up is only half the issue here. In my experience, it's worth spending a bit of money to get a system that allows for a nice easy restoration of data.

For that money, I think I'd hire a couple of hours of a professional nerd's time to restore the data for me, and show me how they did it. I think that would be money much better spent.

The unix command line is not really that intimidating
try this (verbatim ^M = return or control M). Now the DOS command line, that's scary!

man rsynch^M/--backup^M
posted by singingfish at 4:25 AM on September 8, 2005

Maybe I'm missing something, but why not just partition the firewire drive into two parts (use Disk Utility), and then use SuperDuper (which kicks, by the way) to back each system up to its own partition?

SVN is not what you want to be using as you'll never get a bootable version of your original system by dumping it into subversion.

And as a recommendation from someone who used to have to deal with 200 Macs - DON'T use Retrospect. It's really, truly terrible and way too complex.

I would recommend something that isn't so complex. As I already mentioned, SuperDper is great. There's also Deja Vu, Synchronize Pro, and ChronoSync. All three of those are very good.
posted by theNonsuch at 10:21 PM on September 8, 2005

Lets say my internal hard drive crashes. How do I boot from the .dmg file on the external?

Sorry for the late reply. I would boot from a CD (Disk Warrior or OS X installer or something).
posted by hyperizer at 2:29 PM on September 9, 2005