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How can I add a new partition to my HD without reformatting?

Hi, I currently have a 640GB external HD that has 1 partition formatted as HSF+ Now I want to split some of the free space into a new FAT32 partition, without having to reformat the whole HD and losing all my data. I read that I'm supposed to be able to add new partitions in the Hard Disc Utility by clicking the "+" sign, without any loss of data. But in my case the "+" is not clickable and it says that this partition cannot be altered.

Can anyone tell me how to proceed. Or is it impossible without reformatting the whole disc?


ps: I'm running osx snow leopard 10.6.6

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migrated from Mar 11 '11 at 19:00

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marked as duplicate by Ƭᴇcʜιᴇ007, Sathya Mar 12 '11 at 3:51

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This depends on the partition table on the drive.

If it is MBR (Master Boot Record) partitioned, then no, there is no way. You can't dynamically scale partitions.

If it is GPT (GUID Partition Table) partitioned, then you would probably have the + sign and could add a partition without losing data.

If you just reformatted the drive when you set it up to be HFS+, and you didn't repartition it to use GPT, You're probably SOL. Almost all externals I've bought have come partitioned in MBR for compatibility's sake.

Disk Utility should be able to tell you what partition schema your drive is using:

partition table

If it states that its already GPT then we may need to ask a few more questions...

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It says Apple-partition-mapping, so I guess i'll have to reformat the whole thing :'( – Bart Mar 11 '11 at 20:25
Ah. Yeah, that's pretty much the same limitations as MBR. It'll be nice when everybody moves on and GPT can reign. It offers so much over the older, crappier competition. Best of luck with the backup and reparition. Don't make the mistake again and just repartition with APM and reformat. It will [probably] default to the existing partition map on the drive. Make sure you select GPT when repartitioning. – peelman Mar 11 '11 at 20:46
Ok, thanks for the info – Bart Mar 11 '11 at 20:50
I tried it, and it now works :) I can resize the HFS partition now. But the MS-DOS (FAT) partition I made is not resizable. Is that a limitation of choosing FAT? Or is there also a way to make that partition resizable? – Bart Mar 12 '11 at 11:39

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