[bonniescotland]

Can anyone help?
Have bought a Lacie rugged portable hard drive, with firewire and usb2 connections.
I have formatted it on my mac (firewire connection) using lacie setup assistant.
I thought it would be a good idea to be able to use it for both mac and pc, so i then reformatted it as ms-dos but discovered that I can only transfer under 4gig file size, which is a problem for my mac files as I have large video files.

So I then decided to partition the drive, make most of it mac, and then approx 30gig for pc/mac/pc transfer files. (ms-dos for this partition would be fine as no large files)

However when I partition it using disk utility, as apple partition map, it will allow me to partion as mac-os extended, but won't allow me to partition the other ms-dos.

The only way I appear to be able to have one partition as mac-os extended and the other ms-dos is to click options and change the partition scheme to master boot record, but this worries me because this appears to be a windows type partition scheme.
I'd prefer to keep it as apple partition map that way I can use the drive on my intel mac and my older macs.

Having said all this I don't really particularly understand the difference between these partition schemes anyway, I am just gathering from what I read in the options tab that windows type partition not right for a mac.

so is there a way for me to partition an external hard drive part mac-os extended and part ms-dos and still use apple partition map, or should I change the partition scheme to windows type partition (if so will this screw up things when I used the drive on my intel mac?)

Also for the mac partition should I use mac-os extended or mac-os extended (journaled) or the other mac-os extended choices listed?

My mac is running 10.4.9 (no idea if that is leopard or tiger)

[Simon]

Try formatting the disk using GPT (GUID Partition Table). It's what Apple now suggests. It will boot Intel Macs, it supports HFS+ extended/journaled and FAT.

You can then format one partition as Mac OS Extended/Journaled (that's the one you want) and the other for your PC.

[bonniescotland]

thanks for that, I just realised a few sminute ago actually that the GUID partition, the only issue would be will GUID also work if I plug this drive into an old (pre-intel) mac?

Also the other thing that put me off using the GUID partition was that it said you could start up a mac with it, I don't actually understand this but I want my mac to start up using it's internal drive and then I just want the external drive to show on the desktop. but maybe my understanding of start up is not right, because I worry that start up means that my mac won't start unless i have the external drive plugged in. or am i completedly misunderstanding what start up means?

[Simon]

By startup they mean booting your Mac from the external disk. In any case the disk will work if it is attached at startup. What you Mac ends up booting from is determined by you in the Startup Disk pref pane. Or in the boot loader (hold alt/opt at startup).

The GUID disk will also work on a pre-Intel Mac, but it won't boot it. OS X 10.4.6 and newer can partition with GPT on Intel Macs. Although an Intel Mac can boot from an APM disk (I have an OS X install disk that is APM and it boots my MBP just fine) the GUI tools in OS X don't allow you to install OS X on an APM disk in an Intel Mac. However, if you take a PPC Mac and install OS X onto the APM disk, you can then also boot an Intel Mac from that disk. On the other hand a PPC Mac will not allow you to install OS X onto a GPT disk.

[bonniescotland]

thanks for all your help Simon, much appreciated. So it sounds as if my concerns about GUID etc are only really a problem if I want to try and boot up using my external hard drive on certain computers (i.e. older macs etc), so as this is something I have no intention of ever doing on any of my computers then it sounds as if GUID is the one for me, because all I really want is an external hard drive that will work on my current intel mac, older macs and pcs and it sounds as if this will work with them all. So thanks for that advice because I didn't understand the significance of all the partition scheme options before.

Also I kept thinking why would anyone want to boot up from an external drive anyway, but I'm gathering from this and the other post I did recently (the partitioning internal drive post that you also replied to) that some people like to keep their system software on their external drive and this is why they want to boot up from it as opposed to the internal drive, so I'm finally understanding that as well.

Oh and thanks for the startup disk pref pane tip, mine's set to my internal drive and I plan to keep it that way, but it's handy to know in case I ever really did need to boot up from an external drive. Oh lightbulb moment! (sorry couldn't help the corny Oprah reference) I just guessed people like to boot up from an external drive so that if their internal system software isn't working they don't have to reinstall all the CDs, they can just boot up from the external!

[jmiddel]

Exactly, and run repairs from it or even clone the Backup back to the internal if necessary. Especially if you have a new internal.

[bonniescotland]

Thanks Simon, sorry it's taken a little time for me to reply but just to let you know using your advice (using GUID option) I now have an external drive which has a partitiion just for mac and the other for pc/mac. Works perfectly! Thanks muchly! Mind you I am curious I set the pc partition at 29gb as I think I read somewhere that over 30gb is a prob when partitioning? I guess I could just erase and retry at over 30gb and that would answer my question, but as it's working fine now and I don't really need the pc part to be over 30gb I think I'll just leave it as is, but am a bit curious whether it would have worked if I had tried to partition it as over 30gb.
Anyway thanks very much for your advice, it's working really smoothly now!

[Simon]

Good to hear it worked out for you.