[Info-vax] The (now lost) future of Alpha.

[Johnny Billquist]

On 2018-08-07 18:39, Chris wrote:
> On 08/07/18 00:39, Johnny Billquist wrote:
> 
>>
>> Have you ever tried to read, write, or copy a tape under Unix, using the
>> standard tools?
>>
>> Johnny
>>
> 
> Read and write are no problem, but yes, I would imagine
> copying a tape of unknown format might be a challenge. mt,
> dd and tar have always got the job done here, things like
> Sunos distro tape dc cartridges etc, but limited
> experience otherwise.

tar knows about tapes, and deals with them explicitly. But it makes life 
easy by just using a single record size for all records as well.

> Rather than copy, which is slow, a better approach might
> be to copy the tape to disk, then to tape from that. Direct
> tape to tape copy seems a bit archaic and you do need two
> tape drives...

In theory yes, however, in practice there are a big pitfall in that. 
When you copy a tape to disk, you loose information, because tapes have 
blocks, and blocks have a size. This information is sortof a level of 
meta information, which you somehow need to preserve if you store the 
file on disk.

   Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol