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Here is an attempt at a Q&A about partitioning and pdisk.
- What is partitioning?
- Yikes, you are a newbie! Oh, sorry.
Think of each disk drive in your computer as a big bound
notebook. You could use it all for a single topic/subject, but
more likely you would break it up into several sections using
some sort of added on tabs.
Well, partitioning is the computers way of breaking up the
disk into sections. Since it has to record how the disk is
broken up it writes the information on the first few blocks of
- used linux before can't I jut use fdisk?
- Nope. fdisk uses the Wintel/DOS style partitioning,
a completely different scheme.
- why isn't this just fdisk?
- fdisk had a totally lame internal structure and input
parsing. No way I was going to use that.
- why does it look almost exactly like fdisk?
- My boss insisted. Remember, this got written when I was
an Apple employee, for an Apple project.
- why isn't there a real mac partitioner?
- Lack of time. The real focus was to get something in place
for linux. The Mac version was an afterthought.
- why can't I create filesystems using pdisk?
- Two reasons: (1) it is a partitioner, not a filesystem creator
and (2) making it work right on both linux and MacOS was going to
be a lot of work that I didn't have the time to do.
- why can't I install disk drivers?
- Two reasons; (1) I would have had to write or get open source
to MacOS drivers for SCSI and ATA and (2) making it work right on
both linux and MacOS was going to be a lot of work that I didn't
have the time to do.
- why do I need disk drivers?
- Well you don't unless you want a MacOS volume on it. The Mac
won't pay attention to drives that don't have drivers.
- what a patch partition?
- It contains ROM fixes that need to be applied very early.
Only necessary on pre-ROm-in-RAM machines. see Apple technote 1189.
- what is the partition map partition?
- Every block on the disk (except block 0) has to be part of
some partition, so the partition map gets its own partition in
that wonderful recursive way we computer people love so much.
- what are all these drivers?
- The mac insists on loading drivers off of the device. (There
is a certain bootstrap problem there as you may have noticed.)
Different buses (e.g. SCSI vs. ATA/IDE) require different drivers
so CD-ROMs end up with several. Also, supporting patch loading is
usually done with a pair of drivers for each bus type.
- what is this stuff about block zero?
- The MacOS uses block 0 to point to the device drivers, the
partition map entries act as a cross-check on the block 0 info.
- how big should I make my partitioning?
- How should I know.
- do i need a swap?
- do I need drivers?
- Only if you want the MacOS to see the disk.
- do i want more than one linux file system?
- Probably, ask someone else.
- can't you just tell me how big to make this stuff?
- Nope. System keeps changing in size, number of filesystems
to create has a bunch of tradeoffs.
- how can i copy files to a filesystem that the mac can see?
- You can mount HFS (MacOS Standard) filesystems under
- what about RAID support?
- Heck if I know.
- what about USB disks under MacOS?
- I have to implement code to scan the USB bus and all that.
Somewhat hampered by the fact I don't own any USB disks.
- what about Firewire disks under MacOS?
- Apple doesn't give out the Firewire info for free.
Plus, I don't own anything that talks FireWire.
Last Updated: 2000-05-16