Can Leopard partition a backup drive with Tiger on it?

Karen,

Yes, we can dynamically partition a drive, or re-size partitions, in Leopard. One limiting factor in this, assuming there is enough free space on the drive for an additional partition, is the amount of fragmentation inherent in the existing partition(s). There must be bona fide free space at the end of the existing partition in order to reduce its size to accommodate a new partition.

Also, there is always an inherent risk to the partition map, and the underlying directory structures, when using this capability.

In other words, it will probably work for you, but I wouldn't bet any important data on it.

Scott

Karen,

First, and just to clarify things, your drive is already partitioned. It just has a single partition. In the "Partition" tab of Leopard's Disk Utility, you'll see a graphical representation of that partition (just as you would in earlier versions of Disk Utility). The difference is that there will appear a re-sizing "grab tab" at the bottom-right of the icon that represents your current partition (it looks just like the "grab tab" at bottom-right of any application window).

If we are simply re-partitioning a drive, we can choose a new partition scheme using the appropriate pull-down menu, and that scheme will be reflected in the graphical representation (showing however many volumes, aka "partitions" we choose), and they can be adjusted for size. At some point, we would click "Apply" to begin re-partitioning according to our settings. In this scenario, any and all data on the drive would be destroyed.

In your case, however, you'll be dynamically adding a partition to a "live" drive. You'll start by using the "grab tab" to make the one existing volume smaller, by however much space you want to allocate to the volume you'll add. Next, you'll use another new feature in Leopard's "partition" pane, the "+" button below the representation. This adds a new volume in the unallocated space you will have provided by making the first volume smaller. Click the "Apply" button, and your changes will be written to the drive (cross your fingers). Provided all works as intended, whatever data exists on the first volume will not be affected.

With 121 GBs free, you can theoretically create a second volume of 121 GBs. However, I wouldn't expect this to happen in practice. Some of that 121 GBs of free space will actually exist "in the spaces" between the data/files already written to the drive. How much of your free space exists in this state depends entirely on how you have been using the drive, for how long, and the file sizes involved. If, for example, you have ever filled the current single volume entirely, it is likely that some files reside near the end of the drive, with almost all of your free space "in the middle." In this case, Disk Utility will balk at allowing you to make that volume smaller.

Since you have recently "cloned" Tiger to this drive, it is reasonable to assume this won't be the case for you (the drive was probably erased at the time, right?). So, I think you have a good chance of success. And, since you have everything backed up on optical media, convenience will be the issue, not data security.

Scott

Yes, we can dynamically partition a drive, or re-size partitions, in Leopard

Are you sure of that, Scott?

I thought partition reszing was a facet of the GPT partition format used on Intel-based machines, not a facet of Tiger vs. Leopard.

Since the OP is using a PowerPC=based Mac, that option may not be available.

I concur. The HD needs to be formatted using GUID and only works with ICBMs (Intel-chip-based Macs).

I recant my initial assessment. Based on this from Disk Utility's Help, it's doable. But do note the *Back up your data* caveat.

+*Creating new volumes on a disk*+

+You may be able to create multiple volumes on your disk without losing any data. Each volume works like a separate disk. You may need to create a new volume if you want to install multiple operating systems on your computer. Volumes can also help you organize your files.+

+ NOTICE: Back up your data before creating new volumes on your disk as a precaution.+

+*To create new volumes on a disk:*+

+1. Select the disk from the list at the left, and click Partition.+

+2. Select an existing volume in the Volume Scheme list, and click Add (the plus sign).+

+Disk Utility splits the volume into two, leaving the data in one of the new volumes. If the volume is less than half-full, Disk Utility creates two volumes of equal size. Otherwise. it creates one volume large enough for the data, and another volume with the remaining space.+

+3. Resize the volumes as needed.+

+You can drag the dividers between the volumes in the Volume Scheme list, or you can select a volume in the Volume Scheme list, and then enter a value in the Size field.+

+4.Choose how to format the volumes that will be erased or created.+

+For each new volume, select it, enter a name, and then choose a format.+

+5. Click Apply.+

Karen (and Camelot & Baltwo),

Yes, we can re-size and/or re-partition in Leopard, regardless of whether we're using an Intel or PPC machine. Put another way, dynamic partitioning and re-sizing is compatible with both GUID mapped and APM mapped drives.

I, too, thought this was a feature of the GUID mapping exclusively, until I saw these options available on a PPC Machine, with an APM mapped drive.

So Karen, you should be fine with what you have, and you'll be able to adjust the size of the current Tiger partition, then create a new one (given the caveats that I've already mentioned in this thread).

Scott

The ability to resize partitions on a hard disk comes with Leopard, and does indeed work on either a PPC or an Intel machine. The disk can use either Apple Partition Map or GUID. I don't think Tiger Disk Utility allows partition resizing.

The choice of APM or GUID affects boot capability and (perhaps) ability to use Time Machine. PPC machines normally use APM, though I think they may be able to use GUID. Intel machines use GUID.

Note that the partition resize is not totally flexible. The start address of each partition is fixed. You can shrink a partition, or delete an existing partition, to leave a space. If a partition is followed by space you can expand that partition into the space. But you cannot move a partition without losing its contents.