Date: Wed, 27 Feb 2002 07:00:02 -0500 From: gemorga2 <gemorga2@vt.edu> To: scsi@freebsd.org Subject: RE: IDE vs. SCSI partition and slice limits Message-ID: <3C7D3F5E@zathras>
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>===== Original Message From Bruce Evans <bde@zeta.org.au> ===== >On Tue, 26 Feb 2002, Kenneth D. Merry wrote: > >> [ You're sending mail as root. Generally that's a bad thing. ] >> >> On Tue, Feb 26, 2002 at 16:15:11 -0800, Patrick Thomas wrote: >> > >> > I have discovered, through trial and error, that when using IDE drives in >> > FreeBSD I am limited to 4 slices per drive, and 8 partitions per slice. >> > >> > 1. Is what I just described correct, or was my trial and error flawed ? >> >> That is correct. > >For some values of I. The kernel (on i386's) supports 30 slices per drive. >Some utilities only support 4, but it is easy to create another operating >system's utilities to create more. In most cases that you need more, they >will be for another operating system and will already have been created. >Then you just use them. > >> > 2. Do these exact same limits exist for scsi drives, or are the numbers >> > different (and if so, what are they) >> >> The slice limits are a general PC thing, and the partitions are a >> limitation of the FreeBSD disklabel. > >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". To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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