Date: Mon, 26 Jan 1998 10:54:17 -0700 (MST) From: "Justin T. Gibbs" <gibbs@narnia.plutotech.com> To: Bruce Evans <bde@zeta.org.au> Cc: scsi@FreeBSD.ORG Subject: Re: Minor annoyances with ZIP Plus Message-ID: <199801261754.KAA27413@narnia.plutotech.com> In-Reply-To: <199801250804.TAA12845@godzilla.zeta.org.au>
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>>asking for the rigid geometry >>wasn't buying us anything and the code was recently changed to use the >>information returned by the Read Capacity command instead. > > This hasn't actually changed (at least in the current sd driver). All > that changed recently is that Read Capacity is now used to determine the > sector size. Yes. It's my fault for thinking in terms of what the CAM disk driver has been doing for some time. > Read Capacity has always been used to determine the disk size, and Mode > Sense of the rigid geometry page has always been used to initialize > default values for the geometry in the dummy label for the whole disk. > If there is a valid DOS partition on the disk, as is normally(?) the > case for new zip disks, then these default values are not used. In any > case, the geometry in the dummy label for fdisk is only used by fdisk > and sysinstall. Which is exactly the reason why we shouldn't be using the RG page at all. Almost every SCSI adapter we support will not properly boot a system with a physical geometry in the MBR and when you get a new disk drive it doesn't have a valid MBR to override the dummy label. This is why CAM offers a facility to determine the controller translated geometry and to use that in the dummy label. > Summary: everything just works, but the lowest layer is too verbose and > the highest layer (newfs) is too smart. If it just worked, we wouldn't get so many complaints about geometry problems during installs. > Bruce -- Justin
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