Since I have inadvertently caused a bit of a flap and some consternation,
let's see if I can document how partitioning works on PCs. If anyone can
fill in my question marks, or correct me, please do.
Any one hard drive on a PC can have up to 63 partitions on it, not all of
which can hold file systems. These come in three flavors: primary,
extended and logical. This is Microsoft's terminology, so don't expect it
to make sense. This scheme grew up, one could say, metastasized, over the
years. The culprits include Microsoft, Digital Research and others. As I
have just shown, it is confusing even to those who think they know what
they are doing.
At most one partition with a file system on it may be marked
bootable. BIOS, boot loader (e.g. lilo, System Commander) and operating
system limitations may prevent a marked partition from booting, however.
Primary partitions are numbered from one to four only. Each may hold one
and only one file system, of any type. There must be at least one primary
partition on a hard drive. Due to limitations of Mess-DOS and Windows 9x,
these operating systems are often placed on the first primary partition.
Extended partitions may also be numbered from one to four. (I have never
seen partition one made an extended partition, and have not done any
experiments on the point, so I could be wrong about that.) Extended
partitions are containers for logical partitions. As such they do not
contain file systems themselves.
The sum of primary and extended partitions may not be greater than four.
Logical partitions are contained within extended partitions. I conjecture
that you can have up to 16 (64 total possible partitions divided by 4
possible extended partitions) logical partitions to an extended partition,
but have never tested this.
Logical partitions may not overlap with other logical partitions
Similarly, extended partitions may not overlap each other, nor may primary
partitions overlap each other. Primary and extended partitions may not
overlap each other.
A logical partition must be wholly contained within one and only one
extended partition.
So the way to verify a partition table is:
* Identify the primary and extended partitions, one through four. Check
for overlaps between them.
* Identify the logical partitions, 5 through 63 inclusive. Check for
overlaps between them. Check that each partition is wholly contained
within its extended partition.
* Check that one and only one partition is bootable. Check that the boot
loader will support that partition.
That done, and with the high probability of corrections to come, let's
see Laurent's original partition table looks like.
Disk /dev/hda: 240 heads, 63 sectors, 1299 cylinders Units = cylinders of
15120 * 512 bytes
Device Boot Start End Blocks Id System
/dev/hda1 1 277 2094088+ 6 FAT16
/dev/hda2 278 556 2109240 5 Extended
/dev/hda3 * 557 563 52920 83 Linux
/dev/hda4 564 1268 5329800 83 Linux
/dev/hda5 278 556 2109208+ 7 HPFS/NTFS
hda1 Primary. No overlaps.
hda2 Extended. Does not overlap with any primary or extended partitions.
hda3 Primary. No overlaps.
hda4 Primary. No overlaps.
hda5 Logical. Contained entirely within, and fills up entirely HDA2,
and does not overlap any other partitions.
OK, now that I have done all that, I see the mistake I made earlier. I
incorrectly identified hda3 and hda4 as extended partitions when they are
in fact primary partitions.
My apologies to Laurent, and my thanks
--
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