Need advice re partitioning an existing partition

[thatsteve]

Hello.

I've got a 2GB SCSI drive in my LCIII+ and I've got it split in two partitions, one 500MB and one 1.5GB. The 500MB partition has my 7.6.1 system installed on it. The other is blank.

Now, what I want to do is further partition the 1.5GB partition into a couple of smaller chunks. But when I open up the disk tools and go to partition, it looks like it'll blank the whole drive and start from scratch.

Is there a way where I can select to just further break up the 1.5GB partition and leave the 500MB partition untouched?

Cheers!

S

 

[spiceyokooko]

Presumably you're booting from the 500mb partition and trying to modify the 1.5Gb partition with Apple HD setup.

I don't really know Apple HD setup or any of the formatting utilities that come with the System well enough to say whether they can do what you want to do as I mostly use FWB Hard Disk Toolkit for my formatting, but knowing how basic they are somehow I doubt it. I know with HDT you can change the size of the partitions without having to reinitialise the disk but I'm not sure if you can create new ones. Theoretically you should be able to simply highlight the 1.5gb partition, delete it and then create new partitions out of the space you created, but I'm not sure if it works like that in practice.

If you only have access to the System supplied formatting utility, your best bet is to simply back up whatever data you want from the 500Gb drive and boot from a system floppy with formatter, reformat the disk and reinitialise it into the partitions you want.

 

[zuiko21]

I'm afraid you'll have to back up all your data and reformat the whole disk Apple utilites won't let you repartition the disk keeping any other partition untouched.

As for thrid-party utilities, my only experience is with FormatterOne Pro; I think it can do what you want, but only if the disk had been previously formatted with it... most likely other utilities behave the same, but I'm not sure.

Anyway, it's always a good thing to have a back-up copy...

 

[onlyonemac]

Um... I'm not sure but I wouldn't imagine you can sub-partition a disk!

 

[Charlieman]

Apologies for the simplified explanation that follows. I'm trying to explain the complexities rather than to define all of the possibilities.

In ye olde PC world, most systems of the 1980s and 1990s use a simple partitioning system. There is a Primary partition -- which is usually the only one -- and sometimes an Extended partition. The Extended partition is a container for Logical partitions which may be for data or for a different operating system. It is possible to monkey around with Logical partitions without destroying the Primary partition, but few people need to do it. When DOS + Windows was the popular OS choice, simple partitioning schemes were the norm.

This was limiting, of course, when Linux and the newer flavours of DOS/Windows plus Windows NT arrived. FIPS was an early partition manager, followed by more sophisticated tools such as Partition Magic or GNU Parted, the partitioner that accompanied most i386 Linux distros. Nowadays, tools like DiskPart (the built-in Windows partitioner) can perform all sorts of magic; the BitLocker partitioning scripts modify the partition tables on the disk that you use to run the OS.

In ye olde Mac world, Mac users use Apple's partitioning tools or a third party alternative. Most users create a single partition for the OS, applications and data, but behind the scenes, two partitions exist. One small partition contains the partition map describing how the disk is configured and this is always (?) at the start of the disk. The partition map tells Mac OS where to find partitions that Mac OS can use; you can have two or more bootable Mac OS partitions on a disk.

In theory, it is possible to edit the partition map and a few enthusiasts have done this. The logic of how to achieve this can be found in documentation for FIPS or similar. In theory, it is possible for a Mac disk partitioner to do this automagically but it is a risky process. If I were writing such a utility, I'd be very worried about the number of Mac disk partitioners and about how reliably I could interpret the partition map that they write.

Software Architects (Formatter Five and similar?) lasted longest in the Mac market for partitioning tools.

 

[thatsteve]

Thanks for all the info guys. Looks like it's easier to back up and start again! :-/

I really didn't want to admit defeat because I've got no straight forward way of backing up, or at least I thought until just now! I have a ibook G3 running 9.1 here, can I simply copy the contents of the 500MB (7.6.1) partition to a folder on the ibook via the ethernet network, then wipe the LCIII+ and partition how I need, install the system back to the 500MB partition I would have just created (along with several other partitions), and then drag all the files back over the network? I've got a tonne of programs and stuff set up that's taken a good bit of time to get running nicely and I'm leery of queering it up by starting over!

S

 

[Charlieman]

thatsteve asked:

I have a ibook G3 running 9.1 here, can I simply copy the contents of the 500MB (7.6.1) partition to a folder on the ibook via the ethernet network, then wipe the LCIII+ ...

Yes. Boot the LCIII+ from its hard disk and copy the hard disk contents to a folder on a share somewhere else. Repartition. Boot the LCIII+ using the Network Access Disk (if it is not still an Apple download, ask) and copy it all back. Copying it all back will be slower than copying it up.

Notes: The Network Access Disk works with any Mac with pre-PCI architecture that can run System 7. It may work with a Plus, SE, LC etc with 2MB RAM. The disk contains network drivers for built-in LocalTalk and for top flavours of Ethernet card.

If drivers for your card are missing, the Network Access Disk is hackable. And there are other tricks to accomplish a download of your original configuration.

 

[spiceyokooko]

One small partition contains the partition map describing how the disk is configured and this is always (?) at the start of the disk.

On a SCSI disk following Inside Macintosh V, the first block (block 0) contains the driver descriptor map which is the first data read by the boot code in the ROM and contains stuff like number of blocks, block size, number of drivers and location and size of the first driver. The boot code then loads this driver into memory and executes it.

The partition map starts at block 1 and each partition map entry with information relating to it occupies 1 block.