I can’t stand inefficiency. Time Machine is fundamentally a very inefficient mechanism for backing up large files that change. So bad actually that most things like Parallels and VMWare disable backups of your disk images. Here is the basic algorithm:

1) Get the list of files that have changed since the last backup
2) Create new directory in backup store
3) Copy any file that has changed since the last backup
4) Create hard links to any file or even whole directory in the new backup to the last backup for any file that has not changed

Step 1 is pretty efficient for Time Machine as they keep hooks into the filesystem to track those changes as they occur. Step 2 is obviously easy. Step 3 is a doosy. If you change 1 byte in a VMWare image it will copy the several gigs over to the backup store. Not a great result from such small change and that would quickly consume your disk flushing valuable older changes out of the system. Step 4 is also very efficient because hard links are trivial to create and use virtually no space, though they did have to make special changes to HFS+ so that you could hard link directories to make Time Machine more efficient.

The obvious big problem here is that in the case that a file changes at all you need to copy the whole thing to you backup device. Not that viable over the internet or even WiFi for really big files that are updated often like VM images. You might have wondered why Apple is considering integrating ZFS directly into Mac OS X, now you know why. ZFS lets you do something very special: create a snapshot of a whole filesystem. Essentially a copy of that filesystem at a particular point in time and they do this without copying whole files when they change but instead at the block level. This amazing capability is critical in this more efficient way to backup your system with multi-level snapshots.

Enter rsync. Rsync has been around for a long time. It is used by system adminstrators everywhere to efficiently update files in one location with files from another location, even over the internet. It does this by comparing them at the block level and only sending diffs when needed to update files on the other end. Using the right command line options you can essentially make one filesystem look like a carbon copy of another filesystem. Using this in combination you can make a backup solution that is much better than most out there:

1) Rsync your current filesystem to a ZFS filesystem — remote or attached storage
2) Take a snapshot of the resulting filesystem to forever capture its state

Those are the two steps. Nothing more. Here is the script that I use to backup my Macbook Air to my server at home:

#!/bin/sh
cd /Users
time rsync -av --delete sam 192.168.1.90:/Volumes/zdisk/macbookair
ssh 192.168.1.90 sudo zfs snapshot zdisk/macbookair@`date "+%s"`

This results in a set of filesytems that looks like this:

zdisk/macbookair             14.9G   898G  14.6G  /Volumes/zdisk/macbookair
zdisk/macbookair@1225350709   125M      -  14.6G  -
zdisk/macbookair@1225351248   117M      -  14.6G  -
zdisk/macbookair@1225418584  21.7M      -  14.6G  -

This obviously isn’t as awesome as using Time Machine to recover my files because I don’t have a great UI, I have to run a script and generally have to know more about the system than a Time Machine user. However… I can update a VM without sending gigs of data over the internet to back it up or deal with not having a backup at all.

The only downside is that an empty backup still takes about 8 minutes to go through all my files. Next step would be to integrate into the fslogger into the solution and only look at those files that changed for sure.

1. Native Microsoft Office (any version) support
2. Latest Microsoft Office
3. Microsoft Vista
4. Games
5. IE7

Again with the ideal requirements:

1. Runs applications at full speed
2. Executes them in such a way as they appear to be native applications
3. Does not require a Window license

The simplest answer is to use Crossover Office to run applications that work with it, as when it works it satisfies the ideal requirements and then use Bootcamp when you absolutely have to have a true Windows machine. Crossover Office is now robust enough to run Outlook 2003 pretty well along with some older games like Counter Strike: Source though it doesn’t have support for the very latest software. There are cases that are in-between, for example you might not need full speed but you do need full compatibility, then either Parallels or VMWare Fusion ought to work for you, like when you want to run IE7 to view a website. If you are doing anything that requires high non-graphics speed and also high-compatibility like developing software, either VMWare or Bootcamp would be your best bet. VMWare allows you to use more than 1 processor and it out benchmarks Parallels. On the other hand, Parallels is a nicer application and its Coherence-mode (integrates Windows applications into the Mac desktop experience) is better than VMWare’s Unity mode. Neither VMWare nor Parallels run highly graphical twitch games to my satisfaction. Here is a little table to help you make your decision:

• Crossover Office 6.2
  • When it works its the best option
  • Fast, well integrated, runs some games
  • Only option that doesn’t require a Windows license
  • According to CodeWeavers, will work even better under Leopard
• Bootcamp
  • It is just Windows
  • Mac’s are really good Windows machines
• Parallels Desktop 3.o (build 5160)
  • Easier to use than VMWare Fusion
  • Coherence is very mature
  • Does not really run games well
• VMWare Fusion 1.0 (build 51348)
  • Faster than Parallels
  • Unity is OK
  • Lot’s of compatible VMWare appliances
  • Not much luck running games on it

Have any questions about the options? Since I have a license to all of them and use them all for various purposes I would be happy to answer any specific questions about the products.