Largest practical volume sizes for various Pdp-11 OSes?

[Crawford]

Folks,

I've noticed that there are various limitations on OS disk volume sizes depending on the intended OS. Some are hard limits tied to the disk hardware of the time but there may be more practical limits.

Any guidelines or lessons learnt for the more popular/useful OSes (e.g. Unix, rt11, ram, rsts) ?

Thanks,

? ; - )

 

[RSX11M+]

You pose an interesting question here - a logical way to look at it. I'm not aware of any such compilation of numbers vs systems / revisions however.

Earlier drives of course are easy, but after the advent of MSCP disks, the boundaries become blurry. Consequently, one can separate out pre-MSCP OSs and revisions because their disk sizes are known and static.

However any system with drivers for a DU: device can be somewhat elastic. I'm sure there is a theoretical limit to an MSCP Architecture connected device - but I don't know what that number is. Additionally - there were a few revisions of MSCP in both OS drivers, HD assemblies, and controllers - so even if the underlying structure permits huge volume sizes, a particular OS may not be capable of sporting the full range. For example - in RSX, privileged tasks and some utilities needed alteration or at least re-building after an MSCP driver update.

I'll be watching with interest to see if someone has done the research to provide a clear direct answer.