From owner-freebsd-stable Fri Sep 4 20:54:04 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id UAA05925 for freebsd-stable-outgoing; Fri, 4 Sep 1998 20:54:04 -0700 (PDT) (envelope-from owner-freebsd-stable@FreeBSD.ORG) Received: from mail.HiWAAY.net (fly.HiWAAY.net [208.147.154.56]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id UAA05918 for ; Fri, 4 Sep 1998 20:54:01 -0700 (PDT) (envelope-from dkelly@n4hhe.ampr.org) Received: from nospam.hiwaay.net (tnt1-18.HiWAAY.net [208.147.147.18]) by mail.HiWAAY.net (8.9.0/8.9.0) with ESMTP id WAA20208 for ; Fri, 4 Sep 1998 22:52:53 -0500 (CDT) Received: from n4hhe.ampr.org (localhost.ampr.org [127.0.0.1]) by nospam.hiwaay.net (8.8.8/8.8.8) with ESMTP id WAA20987 for ; Fri, 4 Sep 1998 22:17:51 -0500 (CDT) (envelope-from dkelly@n4hhe.ampr.org) Message-Id: <199809050317.WAA20987@nospam.hiwaay.net> X-Mailer: exmh version 2.0.2 2/24/98 To: freebsd-stable@FreeBSD.ORG From: David Kelly Subject: Re: 8mm tape block size max - changed? In-reply-to: Message from "Chad R. Larson" of "Fri, 04 Sep 1998 11:44:21 PDT." <199809041844.LAA15768@freebie.dcfinc.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Fri, 04 Sep 1998 22:17:51 -0500 Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG "Chad R. Larson" writes: > Or, > > dd if=/dev/tape of=/tmp/junk bs=64k count=1 > ls -l /tmp/junk > > should tell you the size of the tape blocks. Agreed. It *should*. But for some reason it doesn't anymore. n4hhe: {553} tar -cvb 20 gifs gifs/ gifs/cycle_large.gif gifs/title_bottom.gif [...] n4hhe: {554} dd if=/dev/rst0 bs=64k of=/dev/null count=1 1+0 records in 1+0 records out 65536 bytes transferred in 2.138313 secs (30648 bytes/sec) n4hhe: {555} tcopy file 0: block size 65536: records 0 to 7 file 0: block size 43008: record 7 file 0: eof after 8 records: 501760 bytes eot total length: 501760 bytes n4hhe: {556} You'll notice 501760 is 49 * 10240 and the last block came up short of 64k. I believe tar correctly wrote the tape with 10k blocksize but the kernel is (incorrectly) combining multiple blocks to fill a single read. I don't believe this has always been the case. n4hhe: {559} uname -a FreeBSD n4hhe.ampr.org 2.2.7-STABLE FreeBSD 2.2.7-STABLE #0: Sun Jul 26 21:19:55 CDT 1998 root@n4hhe.ampr.org:/usr/src/sys/compile/PPRO200 i386 n4hhe: {560} mt stat Present Mode: Density = QIC-150 Blocksize = 512 bytes ---------available modes--------- Mode 0: Density = 0x00 Blocksize variable Mode 1: Density = X3.136-1986 Blocksize = 512 bytes Mode 2: Density = X3.39-1986 Blocksize variable Mode 3: Density = X3.54-1986 Blocksize variable n4hhe: {561} -- David Kelly N4HHE, dkelly@nospam.hiwaay.net ===================================================================== The human mind ordinarily operates at only ten percent of its capacity -- the rest is overhead for the operating system. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message