On Tuesday 23 November 2010 17:18:56 David W Noon wrote: > On Tue, 23 Nov 2010 17:20:02 +0100, Peter Humphrey wrote about Re: > [gentoo-user] Boot partitions (WAS: migrating disks (from mounts to > > disklabels: > >On Sunday 21 November 2010 16:22:15 David W Noon wrote: > >> What I suspect is in the remainder of that space is a hidden primary > >> partition containing a "transparent" bootstrap that augments the BIOS > >> and permits booting from a logical/extended partition. This would be > >> similar to the old OS/2 Boot Manager, although that was hardly > >> transparent. This hidden partition was probably placed there by > >> cfdisk when you first partitioned the drive and started it with an > >> extended partition. The OS/2 FDISK.COM did something similar when > >> the first partition on a drive was not a primary (including Boot > >> Manager). > >> > >> A forensic examination of that area would be of interest. > > > >Including attempting creation of three more primary partitions. If > >your hunch is right, the last will not be created as the allowable > >four exist already. > > No, only 1 primary and Neil's extended partition would currently > exist. So it should be possible to create 2 more primaries, if there > were space on the disk. > > >I don't believe your hunch is right though - it's just too complex to > >be worthwhile for any but a very few customers. > > Not at all complex. OS/2 has had the option to work that way since > about 1987 on 80286 hardware (and written by Microsoft). > > >Nobody's answered my parenthetical question though: why do SCSI and > >IDE interfaces allow different total numbers of partitions? > > They don't. > > The number of primary/extended partitions is limited to 4, and the > number of logical drives is limited by the size of the extended > partition. If you can fit more partitions onto one drive than another, > it is because either the drive is bigger or the partitions are smaller.
Errm, not exactly. SCSI/SATAs are limited to 15 (inc. one extended partition) and old (legacy driven) IDEs are limited to some 63 partitions if I recall correctly. If you use the new libata I think you only get 15 partitions for SATA/PATA. I know, because I remember some years ago getting a bit over-enthusiastic with a new SATA drive and fdisk only to end up with partitions that I couldn't mount ... O_o -- Regards, Mick
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