From owner-freebsd-scsi  Wed Feb 27  7:43: 8 2002
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Date: Thu, 28 Feb 2002 02:43:24 +1100 (EST)
From: Bruce Evans <bde@zeta.org.au>
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To: gemorga2 <gemorga2@vt.edu>
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Subject: RE: IDE vs. SCSI partition and slice limits
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On Wed, 27 Feb 2002, gemorga2 wrote:

> >===== Original Message From Bruce Evans <bde@zeta.org.au> =====
> >No, the slice limits are arbitrary.  PC's support billions of slices.
> >The limit of 30 is related to the first power of 2 that is strictly
> >larger than what was thought to be the corresponding arbitrary limit
> >on the number of "slices" supported in MSDOS and Linux.  This was tested
> >using MSDOS fdisk to create logical drives C: through Z:.  IIRC, MSDOS
> >fdisk wouldn't create any drives after Z:, but someone said that MSDOS
> >supports undocumented drives that can be named using ASCII characters
> >after Z.
>
> So is that 30 slices inside a PC style partition or thirty partitions (as DOS
> considers "primary" partitions).  I heard (probably incorrectly) that a "DOS"
> readable partition table has only 4 "slots" for "primary" partitions.  With
> extended partitions I know you can have lots of "logical drives".

It is 30 logical drives (as DOS mostly considers them; also consider each
of the primary partitions to give a logical drive (even if it is empty)).
The term "logical drive" is more technically correct and also easier to
understand (once you understand it :-), but AFAIK it is not normally used
in DOS-speak for the "drives" corresponding to the primary partitions.
"Logical drive" is spelled "slice" in FreeBSD-speak.

Bruce


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