[Coco] LSN0 C code

[Steven Hirsch]

On Sat, 11 Jun 2011, gene heskett wrote:

> Yes, I've managed to wipe out both a DDS-2, and a couple of Travan
> cartridges before I discovered that.  For both, I was trying to disable the
> drives compression flag, which once turned on, cannot generally be turned
> off by any normal drive command.
>
> I found the secret is to use dd to read the first 32k block out to a file,
> rewind the tape, issue the compress off command without giving the drive a
> chance to re-read the header, then, again using dd, rewrite that label
> header, which will force most drives to update that (&^$#@) flag to off.
> GZip can very easily beat the drives compression ratio, and since amanda
> counts bytes sent down the cable, it knows how much it was written to that
> tape.  I when tape limited, routinely filled a tape to 98% without every
> hitting the EOT signal.  Now I use a big hard drive as 30 virtual tapes and
> don't worry about it.

I'll file that trick away for posterity - thanks.  This is getting 
off-topic, but I am surprised that you trust rotating media for archival 
backup.  I'm a big believer in belt+suspenders.  All my working machines 
have RAID arrays (one software RAID and the other a 3ware smart 
controller) and LTO2 tape drives.  I use a rotating sequence of LTO tapes.



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