Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83 (MC840302); site erix.UUCP Path: utzoo!watmath!clyde!cbosgd!ihnp4!mhuxn!mhuxb!mhuxr!ulysses!allegra!bellcore!decvax!genrad!panda!talcott!harvard!seismo!mcvax!enea!erix!mike From: mike@erix.UUCP (Mike Williams) Newsgroups: net.unix Subject: Block size on dumps (4.2BSD) Message-ID: <735@erix.UUCP> Date: Mon, 4-Feb-85 14:08:59 EST Article-I.D.: erix.735 Posted: Mon Feb 4 14:08:59 1985 Date-Received: Fri, 8-Feb-85 02:06:33 EST Organization: L M Ericsson, Stockholm, Sweden Lines: 16 Dump uses blocks of NTREC (defined in) * 1024 bytes. NTREC is defined as 10. For 1600 bpi this gives a tape "usage" of about 90% (assuming that a block gap is 0.6 of an inch). However at 6250 bpi this becomes about 70% which is not so good. (ie I can't get a 130 Mbyte partition onto one tape). I tried increasing NTREC to 20 and checked that dump and restore still worked, which they did. NTREC of 20 gives about 84% usage. To get up to the 90% at 1600 bpi you have to increase NTREC to 40. Having larger blocks increases the danger of a bad patch spoiling more of the dump, but are there any other obvious disadvantages? Mike Williams {decvax,philabs}!mcvax!enea!erix!mike or mike@erix.UUCP