Return to BSD News archive
Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!harbinger.cc.monash.edu.au!news.mira.net.au!news.mel.connect.com.au!munnari.OZ.AU!news.ecn.uoknor.edu!paladin.american.edu!gatech!news.mathworks.com!fu-berlin.de!news.belwue.de!news.uni-stuttgart.de!uniol!uni-erlangen.de!news.tu-chemnitz.de!irz401!orion.sax.de!uriah.heep!news From: j@uriah.heep.sax.de (J Wunsch) Newsgroups: comp.unix.bsd.freebsd.misc Subject: Re: Cannot Read a SCSI Tape Written by an Unknown Machine Date: 22 Jun 1996 12:53:50 GMT Organization: Private BSD site, Dresden Lines: 31 Message-ID: <4qgqcu$q31@uriah.heep.sax.de> References: <4q6fai$r79@uwm.edu> Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch) NNTP-Posting-Host: localhost.heep.sax.de Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-Newsreader: knews 0.9.6 X-Phone: +49-351-2012 669 X-PGP-Fingerprint: DC 47 E6 E4 FF A6 E9 8F 93 21 E0 7D F9 12 D6 4E chapman@allmalt.cs.uwm.edu (Mark Chapman) wrote: > I have a SCSI DAT tape that was written on an unknown machine type using > tar. The `unknown' is most likely an SGI. (At least, that's the only machine that is known by now to use such a big tape blocking.) > tar: read error on /dev/rst0 : Input/output error > st0: 128874-byte record too big > ******************************** The problem has been discussed on the FreeBSD mailing lists, you might be able to find the traces via the Web interface. Basically, our physio(9) [kernel-internal routine] limits all transfers to 64 KB, i.e. it does split larger requests into chunks of at most 64 KB. This is primarily done to circumvent through problems with busmaster-DMA SCSI controllers that can only handle 16 scatter/gather segments, so no special handling is required to deal with the problems caused by a VM architecture. (16 segments == up to 16 non-adjacent physical pages == 64 KB) The sad news for you: it's impossible to read these tapes with FreeBSD by now. -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE Never trust an operating system you don't have sources for. ;-)