External Hard Drive Back Up Dilemma!

I have a Western Digital Passport Essential SE 750 GB External Hard Drive with saved data from my Dell laptop running Windows Vista and my Custom ASUS Desktop running Windows Vista. I can't seem to get the drive to back up the data on my iMac, I downloaded all the Mac software from WD's site specifically for Macs and all I can do is enable or disable the virtual disk, but the virtual disk isn't visible on the external drive.

This will be because it is not formatted for use on a Mac at the moment.
What format is the drive in?

Kevriano said:

This will be because it is not formatted for use on a Mac at the moment.
What format is the drive in?

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The drive was formatted for Windows probably in NTFS before I bought the iMac. I think my best course of action would be to save the data from my external drive wipe it and then partition 320GB in a MS-DOS file system for my iMac and partition the other 430GB in a NTFS file system for my Windows Vista machines. If I'm correct I can create both partitions on the external drive using iMac Disk Utility. Am I correct?

If you format the external drive to the MS DOS file format (FAT-32) you will not be able to use it with Time Machine nor cloning software such as SuperDuper or Carbon Copy Cloner. The drive should be formatted to the Mac HFS Extended Journaled file system for backup to work.

Disk Utility can not format to NTFS and is really not a good way to format a drive to FAT-32 because it defaults to the GUID partition scheme which will create a small EFI partition on the drive. There is a way to avoid that by selecting MBR instead of GUID. Regardless, you still have to use Disk Manager from Windows to do the format to NTFS.

Thanks for all your help guy/gals I have decide to just pony up the cash for another external drive just for my iMac after reading this article from Western Digital's knowledge support site.

How do I use a WD external hard drive on both a Windows PC and a Mac Apple?

Important Information

It is possible to use a Western Digital external hard drive on both a PC and a Mac. However, there are some things to keep in mind if you want to do this. Moreover, Western Digital does not recommend doing it.

* For both PC and Mac to be able to read the drive, it must be formatted in the FAT32 file format. For assistance formatting to FAT32 in Windows see Answer ID 1364: How to format an external USB or FireWire hard drive as FAT32 in Windows. In order to format to FAT32 on a Mac please see the instructions below. We do have a FAT32 Formatting utility for Windows that reformats older WD external hard drives (Pre-SmartWare and less than 1TB) to their full size, but in only one partition. The FAT32 formatting utility can be downloaded from our Downloads Library. You will find it on your WD drive's Downloads page if it is available for your drive. If this utility does not work for you, there are many third-party applications that are able to accomplish this.

Critical: Never attempt to connect any external drive to multiple computers at the same time. This could quickly damage the drive's partition and corrupt the data on the drive.

* Sometimes, PC's won't read Mac FAT32 formatted drives, and Mac's won't read PC FAT32 formatted drives. You may have to re-format the drive trying both the PC and Mac until you get a format that works.

* Windows 7, Vista, and XP can only (using the actual operating system itself) create FAT32 partitions that are 32 GB's or smaller.

* Mac 10.4.x (Tiger), 10.5.x (Leopard) and 10.6.x (Snow Leopard) can create FAT32 (called MS DOS format in Mac OSX) partitions the full size of the drive.

* There are several limitations to the FAT32 format including a 4 GB per-file limit. This is a file system limitation that affects both Mac's and PC's, and there is no way around it at this time.

* If you are using the same drive on both a Mac and PC, there is always the chance of files being corrupted. Mac's and PC's are different platforms, and their file systems function differently. Please remeber to keep a backup (second copy) of all your files before you start sharing between Mac and PC computers.

Note: Once the data is corrupted, that drive may no longer be recognized by one or both of the computers. The data may also be viewable but inaccessible. At that point, you will need to re-partition and reformat the drive in order for it to be restored and usable. In the process, you will lose all the data on the drive. For that reason, you need to keep a backup of the files you are transferring between computers.