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Trouble with partitioning external HD

J

jla

macrumors newbie
Original poster
Sep 28, 2009
6
0
My intention is to partition an external HD in half allowing it to serve as a backup for a pc running windows xp, and the other half as a backup for a mac(10.5. I am using a Seagate external HD(new) that was initially partitioned on a windows xp computer.The 1st half of the 1TB HD was formatted in NTFS format, and the second half was erased and (I thought) reformatted in HFS plus but when I attempt to use CCC(Carbon Copy) to copy the mac 1/2 of the hard drive, I get this message:

"You may have difficulty booting from this target volume, the underlying disk is not formatted with a partitioning scheme that Apple recommends for Intel Macs."

I have read the recommendations that the external HD need to be partitioned with APM or GPT, but I cannot seem to get to that option now for the mac side of the external HD. In the Disk Utility, the external HD shows both sections of the partitioned drive(the xp section and the leopard). I do not want to reformat the entire drive(both sections) if at all possible. I just want the Mac side of the ext drive to be properly prepared for CCC, and the windows side to remain as is.

Any suggestions would be appreciated.
 
You're going to have trouble with partition maps on a single physical drive that you want bootable in both systems. Windows wants the boot sector to be MBR, while newer Macs want GPT. I can't answer exactly, but you'll need to research dual boot configurations for Windows and Macs. I think it's a bit tricky, which is why we have Boot Camp and virtualization.

Someone hit me if I'm wrong about this.
 
I partitioned the HD into two halves using windows--initially NTFS in both then I attached the HD to iMac to use the disc utility to erase the second half BUT the trouble comes in when I cannot get the Disk Utility to allow me to select APM or GPT for the second half(iMac backup)of the HD. .... For what it is worth, I am just looking to use the huge external HD to backup both computers.

Any suggestions would be appreciated!
 
jla said:
I partitioned the HD into two halves using windows--initially NTFS in both then I attached the HD to iMac to use the disc utility to erase the second half BUT the trouble comes in when I cannot get the Disk Utility to allow me to select APM or GPT for the second half(iMac backup)of the HD. .... For what it is worth, I am just looking to use the huge external HD to backup both computers.

Any suggestions would be appreciated!
Click to expand...

A bump for some help. Having difficulty figuring what to do now...Thanks!
 
jla said:
I partitioned the HD into two halves using windows--initially NTFS in both then I attached the HD to iMac to use the disc utility to erase the second half BUT the trouble comes in when I cannot get the Disk Utility to allow me to select APM or GPT for the second half(iMac backup)of the HD. .... For what it is worth, I am just looking to use the huge external HD to backup both computers.

Any suggestions would be appreciated!
Click to expand...

You cannot set a different partition table for each partition. All you can do is set the partition table of the whole disk which will probably erase the drive. That also means you will have to chose the best one for what you intend to do.
 
I know it's not completely what you want but you could have a single GPT partition allowing you a bootable back up of your OS X partition and a Winclone back up of the Windows one which can be mounted but is not bootable.
 
Do you want to be able to boot from either the Windows or OS X backups? As was mentioned above, there are two parts to formatting a drive. First you pick a partitioning scheme. Any drive partitioned and initially formatted from Windows automatically gets MBR (Master Boot Record) as its partitioning scheme. A drive partitioned and initially formatted from an Intel Mac will default to GPT (GUID Partition Table) and a PPC Mac will default to APM (Apple Partition Map). OS X will, however, let you choose any of the three. An Intel Mac really wants to boot from a HFS+ formatted partition on a GUID partitioned drive.

From the sounds of it, you have a MBR partitioned drive with an NTFS and HFS+ partition. CCC will still back up your data onto the HFS+ partition, but you won't be able to boot from this clone. It is just warning you of this. Had you partitioned the drive from a Mac with the GUID scheme you would still be able to put an NTFS partition on it, but changing now would require erasing the drive as part of the partitioning act.

If you don't need to boot from the CCC backup, I'd just acknowledge the warning from CCC and continue on with the backup anyway.
 
jzuena said:
Do you want to be able to boot from either the Windows or OS X backups?
Click to expand...
I know that this is going to sound completely nuts, but when you say boot from the backups, what to you mean? My intention was to have a backup of everything on both computers in case either computer spontaneously dies on me.

[/QUOTE]From the sounds of it, you have a MBR partitioned drive with an NTFS and HFS+ partition. CCC will still back up your data onto the HFS+ partition, but you won't be able to boot from this clone. It is just warning you of this. Had you partitioned the drive from a Mac with the GUID scheme you would still be able to put an NTFS partition on it, but changing now would require erasing the drive as part of the partitioning act.

If you don't need to boot from the CCC backup, I'd just acknowledge the warning from CCC and continue on with the backup anyway.[/QUOTE]

This sounds exactly like what I did. I am ok with erasing the external HD and starting from scratch as long as it allows me to boot from either partition if need be. Is there an simple way to do this? I am ok with doing this:"Had you partitioned the drive from a Mac with the GUID scheme you would still be able to put an NTFS partition on it, but changing now would require erasing the drive as part of the partitioning act." If I could get a play by play on how to do this, I would be grateful.

Can't thank you enough for your help.
 
Partitioning on an iMac to backup iMac and separate PC

I have already partitioned my external HD on Windows(xp) and this is what I(and another member)think I did:

"From the sounds of it, you have a MBR partitioned drive with an NTFS and HFS+ partition. ....Had you partitioned the drive from a Mac with the GUID scheme you would still be able to put an NTFS partition on it, but changing now would require erasing the drive as part of the partitioning act."

Another member has diagnosed my problem so I could use some guidance. If I erase the drive and start from scratch, can I set up the external HD so that it boots for both the Imac and PC by partitioning on the iMac? If so, how do I go about erasing the drive and repartitioning?

Thanks
 
bump for some help... can anyone give me some guidance on this?Thanks
 
jla said:
I know that this is going to sound completely nuts, but when you say boot from the backups, what to you mean? My intention was to have a backup of everything on both computers in case either computer spontaneously dies on me.
Click to expand...

On a Mac you can hold down the option key during bootup and it will present you with a list of volumes you can start the OS from. If your backup drive is formatted as HFS+ on a GPT partitioned drive and the backup is made from something like CCC you can boot from it instead of the internal drive. If you leave the drive as it is with MBR partitioning it might not show up in the list and if it does it might not work.

I'd go ahead and make the backup even with the warnings and the next time you reboot your Mac, hold down the option key. If you see the backup drive in the list, try to boot from it. If that works you have a fully working solution (I don't think it will work, though). If it doesn't work and you are comfortable knowing that you have a backup of your data but not one that you can boot from if your internal drive dies, then you have a working solution for your needs. If it doesn't work and you really want the ability to boot from the backup, you need to repartition the drive as GPT which will erase data from both the NTFS and the HFS+ partitions.
 
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