I have been given an external hard drive which has been used on a PC, don't laugh!!. I now wish to erase this drive and format it to use as a back up for my iMac and Mac Book. Is it possible to do this once it has been used on a PC? if so what do I need to do?
John Marriott
Hi John,
Before offering advice please note that the methods vary depending on whether you are using this drive with a PowerPC or an Intel Mac, whether you need a start-up drive, whether its USB1, USB2 or firewire -- you don’t tell us. See Stage 2.3 below.
Let’s assume your Mac is four or five years old or newer, running Tiger, Leopard, or Snow Leopard.
STAGE 1
For both PowerPC and Intel Macs you need to format the drive mechanism for Mac instead of PC.
Macs can read PC disks, and store data on them (as on your Memory Sticks), but that formatting doesn’t work with MAC OSX programmes (applications) since these are Unix. trying to copy such files to a PC format drive makes those files unusable, although they can be stored and transferred as disk Images (.dmg).
This means your PC drive will appear in Disk Utility so you can work on it.
Connect your drive to your Mac. Open Disk Utility, then
1.1 select your PC drive in the left column AS A DRIVE MECHANISM,
eg. “250.2 GB SEAGATE i234567ABC”.
The name may have a small square drive icon next to it. (If there are any partitions on the drive mechanism these may be listed -- indented -- below the drive mechanism name).
1.2 Click on that MECHANISM name to select it.
1.3 Click on the Erase menu to find all the options. Typically your PC Drive may be formatted as MSDOS (FAT).
1.4 The format for a modern Mac (OSX) should be
> MAC OS Extended (journaled) < ignore the case sensitive options.
1.5 add a name for the drive (Untitled isn’t very useful, and Macintosh HD reads like your internal drive).
1.6 Note the warnings about data loss, and proceed when ready.
STAGE 2
Now you will need to make at least one partition on your Mac OS Extended (journaled) drive mechanism.
2.1 Choose “Partition”, and select how many partitions you want under Volume Scheme.
2.2 Give it (or each) a name, decide on a size if there are more than one, and…
2.3 Look for the > Options… < button below the Volume Scheme graphic.
“Here be dragons” and your choice will depend on whether you are using the drive with a PPC or an Intel Mac, and whether you want to use it for plain storage or as a start-up drive, etc.
A. If you are just using the drive with an Intel Mac choose GUID Partition Table.
B. If you want to simply store data for a PPC Mac GUID will also be OK.
C. If you want to use the drive as a startup disc with a PPC Mac use Apple Partition Map
If this needs elaboration, look for ‘Partition GUID’ or ‘Apple Partition Map’ in Apple support.
John Marriott 