I was under the impression that you can change a primary partition to an
extended partition in order to create voluminous logical partitions within
that extended partition. I use PM5, and it looks like this is what PM5
does.
Is this correct?
I don't claim to be an expert on partitioning,
Matt
>From: Charles Curley <[EMAIL PROTECTED]>
>Reply-To: [EMAIL PROTECTED]
>To: Expert mailing list <[EMAIL PROTECTED]>
>Subject: [expert] Partition Table
>Date: Wed, 31 May 2000 10:34:39 -0600
>
>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
>
>--
>
> -- C^2
>
>No windows were crashed in the making of this email.
>
>Looking for fine software and/or web pages?
>http://w3.trib.com/~ccurley
>
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