Xref: utzoo unix-pc.general:3566 comp.sys.att:7307 Path: utzoo!attcan!uunet!ginosko!gem.mps.ohio-state.edu!rpi!batcomputer!cornell!rochester!rit!tropix!moscom!ur-valhalla!uhura.cc.rochester.edu!sunybcs!rutgers!tut.cis.ohio-state.edu!n8emr!uncle!jbm From: jbm@uncle.UUCP (John B. Milton) Newsgroups: unix-pc.general,comp.sys.att Subject: Re: Hard Disk questions Message-ID: <569@uncle.UUCP> Date: 8 Aug 89 00:45:57 GMT References: <9186@phoenix.Princeton.EDU> <19995@cup.portal.com> <701@argon.UUCP> Reply-To: jbm@uncle.UUCP (John B. Milton) Organization: U.N.C.L.E. Lines: 57 In article <701@argon.UUCP> ebh@argon.UUCP (Ed Horch) writes: >In article <19995@cup.portal.com> thad@cup.portal.com (Thad P Floryan) writes: >>MB, formatted (std, 17 sec/trk) 42.8 71.2 >> >>MB, formatted (UNIXPC, 16 sec/trk) 40.3 67.1 >>(ignoring the spare sec per track) > >What does the Unix PC do with that extra sector? Is that how it >remaps bad blocks? Yes, that's how "it" does it. 1/17th of the total formatted disk capacity is thrown away to make bad block mapping easier. If there is more than one bad sector on a track, it uses the 17th sector from another track. Below is the output from "iv -vt /dev/rfp000", which shows all the formatting info from the VHB (Volume Home Block), as well as a dump of the bad block table, which I sorted after including in this article, careful examination will show that this bad block table was not created entirely on the first pass. One could argue that a better bad block scheme should have been developed, but this one simplified other problems (1k "driver" logical blocks), and runs fairly quickly. Winchester disk Volume Name: WINCHE 917 Cylinders. 9 Heads per Cylinder. There are 17 Physical Sectors (of 512 bytes) per Track. 153 Physical Sectors per Cylinder, 140301 Physical Sectors per Disk. There are 8 Logical Blocks (of 1024 bytes) per Track. 72 Logical Blocks per Cylinder, 66024 Logical Blocks per Disk. The Step Rate supplied to the Controller is 0. Partition 0: start Track=0, size (in Blocks)=72 Partition 1: start Track=9, size (in Blocks)=5000 Partition 2: start Track=634, size (in Blocks)=60952 Loader starts at Block 2 (size=23 Blocks). Bad Block Table starts at Block 1 (size=1 Blocks). Cylinder 175, Track 3, Sector 4, uses Track 3, Sector 16 as Alternate. Cylinder 352, Track 2, Sector 0, uses Track 3, Sector 16 as Alternate. Cylinder 352, Track 2, Sector 1, uses Track 1, Sector 16 as Alternate. Cylinder 352, Track 2, Sector 12, uses Track 2, Sector 16 as Alternate. Cylinder 359, Track 4, Sector 0, uses Track 3, Sector 16 as Alternate. Cylinder 359, Track 4, Sector 1, uses Track 6, Sector 16 as Alternate. Cylinder 359, Track 4, Sector 12, uses Track 4, Sector 16 as Alternate. Cylinder 359, Track 4, Sector 13, uses Track 5, Sector 16 as Alternate. Cylinder 449, Track 6, Sector 12, uses Track 6, Sector 16 as Alternate. Cylinder 510, Track 7, Sector 0, uses Track 8, Sector 16 as Alternate. Cylinder 510, Track 7, Sector 1, uses Track 7, Sector 16 as Alternate. Cylinder 643, Track 6, Sector 1, uses Track 6, Sector 16 as Alternate. Cylinder 763, Track 6, Sector 0, uses Track 6, Sector 16 as Alternate. Cylinder 763, Track 6, Sector 1, uses Track 7, Sector 16 as Alternate. Cylinder 855, Track 8, Sector 0, uses Track 8, Sector 16 as Alternate. Cylinder 855, Track 8, Sector 1, uses Track 0, Sector 16 as Alternate. The Bad Block Table contains 16 entries. John -- John Bly Milton IV, jbm@uncle.UUCP, n8emr!uncle!jbm@osu-cis.cis.ohio-state.edu (614) h:294-4823, w:466-9324; N8KSN, AMPR: 44.70.0.52; Don't FLAME, inform!