[Info-vax] Backup TK50 tapes

[Stephen Hoffman]

On 2013-02-25 08:57:26 +0000, glen herrmannsfeldt said:

> The unix read() and write() system calls don't throw away the length
> information, but the disk file systems do.

However OP (a computing retronaut) wants tape images for use with the 
simh emulator, which means disk files, which means dd doesn't play 
well, which means rolling a custom dd script to deal with the variant 
block sizes on the distro tapes, or rolling custom tools, or reusing 
existing tools.

> Now, if you use ibs= and obs= then dd will reblock the data, even if
> you didn't want it to, but also if you did.

OP might eventually want to replicate tapes from tape images, or 
regenerated from OpenVMS itself.  OP might also eventually want to 
enjoy tape boots via simh and its tape emulation, too.   The 
performance of the emulation will be vastly faster than the original 
tape hardware, though the capabilities of Standalone BACKUP will still 
be grossly limited.


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