Backup Mac and PC on same external drive

Here's some guidance. Use FAT32 format.
http://www.myfirstmac.com/index.php/mac/articles/1-external-hard-drive-for-your- mac-and-pc

 Cheers, Tom 😉

Unfortunately your link to the drive didn't get entered fully and doesn't work.

Unfortunately it's hard to have your cake and eat it when it comes to PC plus Mac drives. Ideal for the Mac is when you can use a utility to clone* (make a 100% bootable backup copy) to an external drive. However, this means the external has to be formatted for a Mac and can't be used at all by a PC (well, not easily).

As mentioned in another post, FAT32 can be used easily by a PC, and Macs aren't too bad at using it (I have had a few small problems on occasion). However, the one-click backup utilities can't use FAT for cloning. You can still drag groups of files to the drive if all you want is data backup, but this can be tedious and tricky under OSX.

*A bootable clone is an exact copy of your drive which is capable of booting your computer. Making a copy of your computer which is capable of actually starting the computer requires special copying procedures. Some people just back up data files but if you have problems you have to reinstall all your operating system and all your applications. With a bootable clone you just start up from the backup drive and clone back everything.

Look at Mac Backup - Mac Backup Software, Hardware, and Guides for Your Mac
http://macs.about.com/od/usingyourmac/tp/backuphub.htm
Mac OS X data backup FAQ http://www.macmaps.com/backup.html

You can use CarbonCopy Cloner @ http://www.bombich.com/software/ccc.html , or SuperDuper @ http://www.shirt-pocket.com/SuperDuper/SuperDuperDescription.html , or IBackup @ http://www.grapefruit.ch/iBackup/index.html , or Silverkeeper @ http://www.lacie.com/silverkeeper/ or the Restore function of Disk Utility included in OS X.

 Cheers, Tom 😉

If one wants to have a native Windows-readable volume together on the same drive with a complete Mac clone, the whole situation gets somewhat complicated. With a PPC Mac you can still create a clone which can fully restore the HD in the event of a crash, but the clone will not be bootable.

A bootable clone is always more desirable, for two reasons: First, in the event of disaster you always need to boot from "somewhere" and then run a program that will copy the clone back to the internal HD. It's convenient and easy for that bootable "somewhere" to be the clone volume itself. Second, a bootable clone is testable - you can tell in advance whether it is good by simply booting from it and making sure it works OK. However even if a clone cannot be booted, it can still restore your system. The OS install disc has a copy of Disk Utility on it, and Disk Utility has a "Restore" tab which essentially acts similarly to the cloning software listed above. So in the event of a crash, you could boot from the install disk, run Disk Utility from there, erase the internal HD, and then use the non-bootable clone volume as the source for the restore, with the internal HD as destination.

I mention all this because although less desirable than a bootable clone, a non-bootable clone is the only option for a PPC Mac if you also want the drive to have a FAT32 partition that Windows can read natively. A disk drive has two levels of formatting - an overall level called the "partition scheme", and an individual level called the "volume format" which can be different for each partition. In a nutshell - a PPC Mac requires a drive "partition scheme" called "Apple Partition Map" in order to boot from any volume on the drive, and you cannot create a FAT32 partition on a drive with an Apple Partition Map partition scheme. If the overall partition scheme is instead Master Boot Record, then you can indeed create both a FAT32 partition and an HFS+ (Mac OS extended) partition on it, and you can use cloning software to create a good clone on the Mac-formatted partition. But such a clone won't be bootable on a PPC Mac - again, a PPC requires Apple Partition Map for booting.

An option to "have it all" might be to partition the drive as APM and format the volumes exclusively for the Mac, allowing you to have a bootable clone there, and then to install a product like MacDrive on the Windows PC so that it can read such a Mac-formatted volume.

Perhaps the most practical option would be to just buy a second external drive, one for each computer. Each could then be easily formatted optimally. They are not that expensive these days.