Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!purdue!decwrl!sgi!johnm From: johnm@voltron.SGI.COM (Foosball Addict) Newsgroups: comp.periphs Subject: Re: Helical-Scan Query Message-ID: <16266@sgi.SGI.COM> Date: 21 Jun 88 23:18:04 GMT References: <2648@usceast.UUCP> <11959@mimsy.UUCP> <1044@cfa.cfa.harvard.EDU> Sender: daemon@sgi.SGI.COM Organization: Silicon Graphics Inc, Mountain View, CA Lines: 13 In article <1044@cfa.cfa.harvard.EDU>, wyatt@cfa.harvard.EDU (Bill Wyatt) writes: > The Exabyte 8mm system uses a special head that DOES allow > read-after-write. Thus, blocks in error are caught and rewritten > right away, some number of physical blocks down the tape. ^^^^^^^^^^ The Exabyte drive does a read after write to compare and if there are any errors, it re-writes the date 11 blocks away. The reasoning is that typical media flaws are horizontal in nature so the block the data is re-written to is skewed off the line the error was detected. johnm