Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!chinacat!chip From: chip@chinacat.Unicom.COM (Chip Rosenthal) Newsgroups: comp.unix.xenix.sco Subject: Re: Hard disks with > 1024 Cylindars Message-ID: <1535@chinacat.Unicom.COM> Date: 31 Aug 90 18:19:14 GMT References: <1990Aug31.022148.5775@gpu.utcs.utoronto.ca> Organization: Unicom Systems Development, Austin, TX Lines: 26 In article <1990Aug31.022148.5775@gpu.utcs.utoronto.ca> utgpu!rom!mark, utgpu!rompub writes: >The disk has 1747 cylindars, 7 head and 54 sectors/track. [...] The SCO ODT >documentation suggests that such a disk is compatible as long as the root >partition doesn't cross over the 1024 cylindar boundary. The problem is that the peecee BIOS can't grok more than 1024 cylinders. Until UNIX is up and flying, you are a slave to the limitations of the BIOS. One of the activities during this stage is to load in /boot and then /unix. Therefore, they must be accessible by BIOS. If your root partition is bigger than 1024 cylinders then /boot or /unix could be sitting in a region which is inaccessible. So, limiting /dev/root to 1024 cylinders guarantees they can be loaded. Some ESDI controllers, such as the WD1007, do remapping, and present a different disk geometry to the system. Thus, as far as the system is concerned the disk *is* less than 1024 cylinders. As a practical matter, if you use a reasonable disk divvy, you generally aren't going to have filesystems this large. Oh yeah, why are we talking about unix in comp.unix.xenix.sco anyway? -- Chip Rosenthal Unicom Systems Development, 512-482-8260 Our motto is: We never say, "But it works with DOS."