Date: Tue, 23 Aug 2016 13:20:17 +0200 From: Gerhard Schmidt <estartu@ze.tum.de> To: Dimitry Andric <dim@FreeBSD.org> Cc: freebsd-stable <freebsd-stable@freebsd.org> Subject: Re: Problems while reading from /dev/cd0 Message-ID: <83cc5126-2044-acc4-854c-96ef0d2ca458@ze.tum.de> In-Reply-To: <66E3F5E4-F640-4E05-A2CF-E7AD5F7D8327@FreeBSD.org> References: <ba79f0d6-a9e5-623c-d1b7-fb188202befb@ze.tum.de> <66E3F5E4-F640-4E05-A2CF-E7AD5F7D8327@FreeBSD.org>
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Am 23.08.2016 um 13:12 schrieb Dimitry Andric: > On 23 Aug 2016, at 08:50, Gerhard Schmidt <estartu@ze.tum.de> wrote: >> >> I'm having some very curios Problems while reading from an BD-R recorded >> as a tar directly on the disk without a filesystem. >> >> When i try to read the Disk via 'tar tvvf /dev/cd0' >> >> i get the following output >> >> -rw-r--r-- 0 root wheel 5793264611 1 Jan 2015 file1.db >> tar: Error reading '/dev/cd0' >> Archive Format: POSIX ustar format, Compression: none >> tar: Error exit delayed from previous errors. >> >> reading the whole file via 'dd if=/dev/cd0 of=backup.tar bs=2048' and >> than 'tar tvvf backup.tar' the file is read without a hitch. So the data >> on the disk is OK but can't be read directly by tar. >> >> if i try the dd without the bs=2048 i get >> >> dd: /dev/cd0: Invalid argument >> 0+0 records in >> 0+0 records out >> 0 bytes transferred in 0.000115 secs (0 bytes/sec) >> >> So there is a problem reading anything other than 2048 byte blocks from >> a Disk. > > Have you tried tar's -b option, to set the block size 2048? Maybe that > will help. It does partially. extracting the files work but testing the archive with tar t fails. Estartu -- ---------------------------------------------------------- Gerhard Schmidt | E-Mail: schmidt@ze.tum.de Technische Universität München | Jabber: estartu@ze.tum.de WWW & Online Services | Tel: +49 89 289-25270 | PGP-PublicKey Fax: +49 89 289-25257 | on request
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