Xref: utzoo comp.unix.questions:15592 comp.unix.wizards:17604 Path: utzoo!attcan!utgpu!watmath!iuvax!uxc.cso.uiuc.edu!tank!mimsy!chris From: chris@mimsy.UUCP (Chris Torek) Newsgroups: comp.unix.questions,comp.unix.wizards Subject: Re: 8mm tape length for dump Message-ID: <18999@mimsy.UUCP> Date: 11 Aug 89 10:08:54 GMT References: <412@h.cs.wvu.wvnet.edu> Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742 Lines: 35 In article <412@h.cs.wvu.wvnet.edu> fuhrman@b.coe.wvu.wvnet.edu (Cris Fuhrman) writes: >Can anyone tell me what the length for an 8mm tape drive is >while using dump in SUN OS 3.5? No. (That is, no one can tell you.) The length you give to dump is plugged into a formula designed for 9-track tape reels at 800, 1600, and 6250 BPI, and not for any of the cartridge formats. Moreover, all existing 8 millimeter tapes (which all use Sony transports, Sony cartridges, and Exabyte's data format, with the drive electronics being from Exabyte, so as it happens it does not matter which manufacturer's 8mm tape drive and cartridge is being used; but this is an unusual and probably temporary situation) are capable of writing either `long tape marks' or `short tape marks', and the amount of data that will fit onto a single cartridge depends to a great extent on how many long tape marks are written. This in turn depends on whether your software and hardware uses long or short tape marks, and on how many files you put on a cartridge. In general, however, the average installation has less disk data to back up than fits on a single one of these cartridges, so any length close to infinity suffices. We have been using the command dump 0ufds /dev/tape/1n 6250 32000but the 32000 here is just a WAG, and depends on this `infinite length' property. -- In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163) Domain: chris@mimsy.umd.edu Path: uunet!mimsy!chris