From owner-freebsd-questions@FreeBSD.ORG Tue Oct 25 06:17:46 2005 Return-Path: X-Original-To: freebsd-questions@freebsd.org Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id E42EE16A41F for ; Tue, 25 Oct 2005 06:17:46 +0000 (GMT) (envelope-from aleksandr.derevianko@ru.transport.bombardier.com) Received: from smtp2.transport.bombardier.com (smtp2.transport.bombardier.com [20.133.32.2]) by mx1.FreeBSD.org (Postfix) with ESMTP id 3811443D49 for ; Tue, 25 Oct 2005 06:17:45 +0000 (GMT) (envelope-from aleksandr.derevianko@ru.transport.bombardier.com) Received: from EMEAML01.UK.BOMBARDIER.TRANSPORT.COM (emea-ml01.atle.bombardier.com [10.157.248.21]) by smtp2.transport.bombardier.com (Switch-3.1.6/Switch-3.1.6) with ESMTP id j9P6Hh2n007152 for ; Tue, 25 Oct 2005 08:17:43 +0200 (CEST) Sensitivity: To: freebsd-questions@freebsd.org From: aleksandr.derevianko@ru.transport.bombardier.com Date: Tue, 25 Oct 2005 10:17:43 +0000 Message-ID: X-MIMETrack: Serialize by Router on EMEA-ML01/Server/Transport/Bombardier(Release 6.0.3|September 18, 2003) at 10/25/2005 07:20:01 MIME-Version: 1.0 Content-type: text/plain; charset=US-ASCII Subject: NEC DVD_RW - file read problems. X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 25 Oct 2005 06:17:47 -0000 Hello All, I have the following problem: OS: FreeBSD 4.11-RELEASE. DVD RW: acd0: DVD-R <_NEC DVD_RW ND-3500AG> at ata1-master UDMA33 I use DVD R's primary for data backup. The backup data is archived and splitted on files ~500Mb size, which was written on DVD-R's. I have also store the MD5 sums of those files in small checksum file. The problem is: sometimes then i check content on DVD the checksum is differs. Where is no read errors on console, and several attempts to calculate checksum return different results. bash-2.05b# grep 00001 /cdrom/md5.sums acc8b491f03bfa01e341808773a6f94f depot.147.tar.00001 bash-2.05b# md5 /cdrom/depot.147.tar.00001 MD5 (/cdrom/depot.147.tar.00001) = d821bd902c4b0e9c12510f302c10ee71 # File seems cached in RAM bash-2.05b# md5 /cdrom/depot.147.tar.00001 MD5 (/cdrom/depot.147.tar.00001) = d821bd902c4b0e9c12510f302c10ee71 bash-2.05b# umount /cdrom # After unmounting and mounting again - different (correct) checksum. bash-2.05b# !mou mount /cdrom bash-2.05b# md5 /cdrom/depot.147.tar.00001 MD5 (/cdrom/depot.147.tar.00001) = acc8b491f03bfa01e341808773a6f94f # Now the checksum is OK. It seems for me that sometimes device correct soft read errors on media, and sometimes - does not. Does anybody have the same expirience (i.e. checksum differs without read errors) ? Best Regards, Alexander Derevyanko