Date: Sun, 5 Mar 1995 08:32:15 -0800 From: patl@asimov.lashley.slip.netcom.com To: hsu@cs.hut.fi Cc: freebsd-current@freefall.cdrom.com Subject: Re: Wiring Message-ID: <9503051632.AA05762@lashley.slip.netcom.com>
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|> # Beginning with FreeBSD 2.1 you can wire down your SCSI devices so |> # that a given bus, target, and LUN always come on line as the same |> # device unit. In earlier versions the unit numbers were assigned |> # in the order that the devices were probed on the SCSI bus. This |> # means that if you removed a disk drive, you may have had to rewrite |> # your /etc/fstab file, and also that you had to be careful when adding |> # a new disk as it may have been probed earlier and moved your device |> # configuration around. |> |> # This old behavior is maintained as the default behavior. The unit |> # assignment begins with the first non-wired down unit for a device |> # type. For example, if you wire a disk as "sd3" then the first |> # non-wired disk will be assigned sd4. |> |> Would it be better to by default try to wire the first 4 disks? Here's a completely radical idea... Make the canonical device names follow the Solaris/SvR4 convention: cWtXdYsZ where W=controller number, X=SCSI target, Y='drive' (SCSI LUN) number, and Z=slice/partition/sub-unit number (for devices that support any similar concept). Then make /dev/sd*, /dev/st*, etc. symlinks to the appropriate canonical name. The links could be created at boot time using the current algorythm. Anyone who wants fixed allocation can simply refer to the canonical name in the fstab (or any other reference...) -Pat
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