+1 Partition - Is it safe?

Hi there

I have , after many hours of hard work, managed to install both Windows XP and Ubuntu on my iMac( by following this this guide) and I have rEFIt as my boot manager.I have one harddrive which is 750G and it's partition looks like this:

Macintosh:~ ballena$ diskutil list

/dev/disk0

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *698.6 Gi disk0

1: EFI 200.0 Mi disk0s1

2: Apple_HFS Macintosh HD 599.9 Gi disk0s2

3: Microsoft Basic Data 27.9 Gi disk0s3

4: Microsoft Basic Data Windows 70.4 Gi disk0s4

As you can see I have two partition but I want one more jHFS+ partition where I can save all my personal files. But I have heard that you only can have 4 partition on the same HDD. Is that true? Will Windows or ubuntu stop working if I resixe my Apple_HFS_Macintosh_HD partition and make another one? Because Windows stop working once when I added a new partition - but this was when I installed Windows with Boot Camp only and made the partition with the BC-tool. which I haven't now.

So dare I make another partition from mac Mac-partition or not? I appreciate any help I can get with this.

/Ballena

#488364

No it's not true, you can have up to 16 partitions.

But let's clarify a little:

Every hard drive has a "master boot record" or "MBR", which has a table where partitions are stored.

This table has only space for 4 partitions. So, those partitions (which are in that table) are called "primary partitions".

So, to be able to have more than that, each partition can be made to point to another table (which is somewhere in the hard drive). This poses a problem: it can't be used as a partition anymore, now is a table instead, which contains 4 more partitions, called "logical partitions".

So, you can have up to 4 primary partitions, or up to 16 logical partitions (but no primary partitions then).

Indeed you can have:

Up to 4 primary partitions, no logical ones.
Up to 3 primary and 4 logical partitions.
Up to 2 primary and 8 logical.
Up to 1 primary and 12 logical.
No primaries, and then 16 logical partitions.

Hope this clarifies a little.

In you case you have 4 partitions, but it doesn't say if those are primary or logical. If at least one of them is logical then yes you can make another one.

I don't think Windows or Ubuntu would stop working if you resize the apple partition.

Note: I don't see the Ubuntu partitions in the list. Where are then?

#488378

Interesting! I didn't know there were primary and logical partitions. How do I know whether a partition is primary and stored in the MBR or not? I hope the Apple partition is a logical one because there is much space I want to release and make a new partition off.

Ubuntu is installed on the third partition (disk0s3) and converted to ext3. I don't know why Diskutil says it's a Microsoft Basic data.

Thanks for answering.

/Ballena

#488383

If you can boot Ubuntu, then you can run gparted from it (gksu gparted from a terminal... if it's not installed then just install from synaptic). I wouldn't recommend it to resize Apple partition (and don't know if it even supports that) but will allow you to "see" (graphically speaking) which partitions are logical and which are primary.

#488392

matonga, I think that was the best explanation of primary and logical partitions I've read so far.

#488429