I need to add to a volume in one of my partitions on an external hard drive. I looked at the help section and followed the instructions that say in order to add to a volume you will have to erase the second volume. When I click on the second volume, the + - keys are grayed out, and the box says this volume will not be erased.
I think that's part of a new partitioning scheme of Apple's for hard disks that was designed for Boot Camp, but must also be possible on all disks. Be glad, it means you won't be needing to save a backup of that data during the repartitioning.
This is possible but you must be careful about doing it. You cannot create a second volume unless there is sufficient contiguous free space on the drive and the new volume size would be limited by the amount of contiguous free space.
Open Disk Utility, click on the drive entry (mfgr.'s ID and drive size), click on the Partition tab in the DU main window. Note the blue shaded space in the partition sizer. That's the amount of occupied space. The white space is free. Move the sizer's bottom right gadget up but do not shrink the size beyond the blue area or you will lose data on the drive. Click on the Apply button. After the re-sizing finishes click on the "+" button at the bottom of the partition sizer. A new volume will be created in the free space you just created above.
Please backup before you do the above, because if there's a problem you could lose everything on the drive.
There are three main disk partition formats used today:
APT (Apple Partition Table)
GUID
FAT
APT is the classic Apple partition format used for years and is required for any boot disk on a PowerPC-based Mac.
GUID is Apple's newer format and is required for any boot disk on an Intel-based Mac.
FAT is the Windows standard and is often the default on external drives (lowest common denominator).
GUID is the only format that supports live editing of partition tables (e.g. the ability to add/delete partitions without reformatting).
If your disk is APT or FAT then you have to reformat the drive to change the partition setup.
You can use Disk Utility.app to see which partition table format is in use - just select the drive in the left-hand list and look at the info at the bottom of the window.
If it's a GUID-based disk you can then click the Partition tab at the top and resize existing partitions and/or create a new one.
My Disk Description says: DMI
If I want to erase everything and start over, I click on partition and under options is: Choose a partition scheme appropriate for the way you will use this disk:
GUID Partition Table
Apple Partition Map
Master Boot Record
When I originally partitioned the external, I didn't know I had to choose one of these. How would I know which one to choose? Right now it says this volume will not be erased and everything else is grayed out.
My external says it's a GUID, it has to be since it's my Time Machine. here's my dilemma. I have the external with two partitions. I wanted to add a partition to it. everytime i try i get the following:
"partition failed with the error: filesystem verify or repair failed."
