Re: Data recovery from corrupted tapes

On Fri, 27 Dec 2002, Pete Gonzalez wrote:

> Won't it automatically rewind to the beginning of the tape?
> Is there a way to just dump bytes to a file, ignoring errors?

For the ftape drives, error checking and recovery are done in software
by the driver.  The tape is read in 10K blocks, which consist of 512 byte
sectors.  There are extra (2, I think) sectors in each block which allow
reconstruction of sectors which have CRC errors.  This is from the last time I
looked at the source.  It is certainly possible to get the raw sectors from the
damaged tape, but someone will have to go to the source to see whether there is
already an option for this.  TR-3 tape hold only 1.6G, so it is easy enough to 
store the raw contents of the entire tape on disk for recovery on a modern IDE
disk (e.g. $80 for 40G at MicroCenter) that will work with your older 
computer with a TR-3 drive.

I suggest that you not attempt to read the tape you are trying to recover
until you have experimented with another tape that you don't care about.
Each pass of the read head wears it out a little more, making things 
worse.  Also, set your valuable tape to write protect to prevent accidents.

If I have time, I will look at the source again, but don't wait for me.
I have a TR-3 drive and tapes on my old Pentium 200 - which is now an
X-server client for our new system.  I invested in a 10G TR-5 IDE tape 
drive for our new system.  The old system was using 3 TR-3 tapes for
a full backup (which didn't include caches and such), and each tape
took all night.  And that was with only 6G of the 15G disk allocated.

-- 
			Stuart D. Gathman <[email protected]>
      Business Management Systems Inc.  Phone: 703 591-0911 Fax: 703 591-6154
	"[Microsoft] products are even less buggy than others, in terms of
	    per capita usage." - Steve Balmer, Microsoft Corporation

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