Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 13 Apr 2001 03:14:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 13 Apr 2001 03:14:34 -0400 Received: from hood.tvd.be ([195.162.196.21]:63922 "EHLO hood.tvd.be") by vger.kernel.org with ESMTP id ; Fri, 13 Apr 2001 03:14:27 -0400 Date: Fri, 13 Apr 2001 09:13:27 +0200 (CEST) From: Geert Uytterhoeven To: lomarcan@tin.it cc: linux-kernel Subject: Re: SCSI Tape Corruption - update In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 13 Apr 2001, Geert Uytterhoeven wrote: > On Thu, 12 Apr 2001 lomarcan@tin.it wrote: > > It seems that the tape is written incorrectly. I wrote some large file > > (300MB) > > and read it back four time. The read copies are all the same. They differ > > from the original only in 32 consecutive bytes (the replaced values SEEM > > random). Of course, 32 bytes in 300MB tar.gz files are TOO MUCH to be > > accepted :) > > In my case, the 32 bad bytes are always a copy of the 32 bytes 10K before (10K > = blocksize of tar). Can you verify that's the case for you as well? For > reference, I have approx. 6 sequences of corrupted data when writing 256 MB to > tape. Reading gives no problems. Forgot some things... It also happens with dd, so it's not a bug in tar. If I set the tar blocksize to 512 bytes, the offset changes to 512 bytes as well. If I set the tar blocksize to 57*512 bytes, I didn't see a problem (however, could have been `good luck'). The problem seems to be there since at least 2.4.0-test1-ac10, which means quite some people may no longer have known good backups of their valuable data (of course we should not run 2.[34].x kernels on our systems, right? :-) Since you have a different SCSI host adapter, the problem is most likely in st.c. I was thinking of writing `predictable' data (or checksummed blocks or so) to tape and add some data verification tests to st.c at the very last moment before it sends a write command to the SCSI host adapter, but I haven't found time for that yet. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/