Xref: utzoo comp.unix.admin:1548 comp.sys.sgi:9364 Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!samsung!uunet!hela!lokkur!scs From: scs@lokkur.dexter.mi.us (Steve Simmons) Newsgroups: comp.unix.admin,comp.sys.sgi Subject: Re: How do I read a bad tape (tar)? Keywords: tar tape sgi unix Message-ID: <1991Apr9.225311.6534@lokkur.dexter.mi.us> Date: 9 Apr 91 22:53:11 GMT References: <1991Apr8.231456.391@gpu.utcs.utoronto.ca> <1991Apr9.030501.23536@odin.corp.sgi.com> Organization: Inland Sea Lines: 43 olson@anchor.esd.sgi.com (Dave Olson) writes: >In <1991Apr8.231456.391@gpu.utcs.utoronto.ca> topix@gpu.utcs.utoronto.ca (R. Munroe) writes: >| I am having trouble extracting some important data from a cartridge tape. >| I used tar and now can not retrieve the data. The tape drive whirrs and >| clicks a couple of times and then the system tells me to insert the next >| tape and press to continue. I know the data is on the tape - it justs >| seems that there is a little snag that makes the system think it's >| reached the end of the archive. Question - is there anyway way of retrieving >| the data (whatever is left of it) by either: >| >| 1. Some unix command that will read past the bogus 'end of archive'. >| >| or >| >| 2. Are there any companies that specialize in data recovery that could help. >| >Unless you are getting kernel messages on the console or in SYSLOG, odds >are VERY high that someone overwrote the beginning of the tape, perhaps >by doing a 'tar c' with no args (fixed in the next release to be a >no op, instead of trashing the tape), when they meant 'tar t'. >If so, there is no hope. The firmware on the drives refuse to read >past the EOD marker. Besides, it erased a part of each track when >the the 'tar c', or whatever was done. This is one of thoese FAQ >that shows up in all the comp groups from time to time. Remember, >the write protect switch is your friend! Hmmm...some help might be possible here. First, one needs to trick the drive into reading past the EOT (not EOD) marker. This *can* be done with some drives (I've done it), as long as one is careful. An EOT marker is two tape marks. So *if* the conjecture about a small tar blotzing the head of a large one is true, one could do so by doing mt -f fsf 1 ; mt -f fsf 1 Now the tape is positioned past the EOT mark. Use GNU tar to read the damaged data. -- "FACT: less than 10% of the psychiatrists in the US are actually practicing cannibals." Rod Johnson