I made an old tape with:
tar -cvb 20 -f /dev/nrst0

I try this:
vax@linkdead bash$ tar -tvf /dev/rst0  
Mar 20 10:39:46 linkdead /netbsd: st0: block wrong size, 20 blocks residual
tar: read error on /dev/rst0 : Input/output error

Has the default hardware blocksize changed recently?  Is there anything
I can do to recover my data (aside from booting from an old kernel, which
I will soon try, but then I'll have to copy all the data to the hard disk)!?

Thanks
Please cc me in all responses.

PS: If you can give me _any_ info about block sizes, blocking factors, etc,
it would be great help!  I'm compiling a FAQ.