On 2014-11-07 02:58, Anton Aylward wrote:
PDP-11 and early Vaxen had a similar problem. The dis controller could support up to 8 spindles. Good, you think. 4K file system, 512 byte sectors, 8 drives, PARALLELISM!
No! Could only transfer to one spindle/arm at a time. best effort, of you hand managed the control queue, and had a controller with dedicated DMA that could fetch the control blocks that you set up and chained was to have
But Linux can parallelize even on PATA hardware. It can send a read chunk command to the disk, and instead of waiting, send another command to another disk - maybe even on the same cable, I'm unsure. This is what allowed us to burn dvds, for instance: reading from one device, writing to another, and not being stuck waiting for the next chunk. You could even do some other "heavy" operations at the same time, on a puny Pentium 1. On SATA hardware this is even more powerful. We no longer are limited by the early far west explorers capabilities. No more wood wagons: we have trucks, locomotives, planes, cars... ;-pp -- Cheers / Saludos, Carlos E. R. (from 13.1 x86_64 "Bottle" at Telcontar)