[Info-vax] File I/O BandWidth Versus Disk I/O Bandwidth

[Lawrence D'Oliveiro]

This book I’m looking at on filesystem design mentions the paper by 
McKusick, Joy, Leffler and Fabry in the August 1984 “Communications of the 
ACM” on the Berkeley Fast File System (FFS, later became more widely 
popular as UFS).

This was a breakthrough, at least in the Unix world at the time, because 
the previous filesystem could only make use of 3-5% of the available disk 
bandwidth, while FFS took this to more like 47%.

Back then, other OSes (like VMS) did not try to hide from applications the 
fact that file space allocations were done in units of sectors (or some 
multiple thereof). Whereas Unix pioneered the idea that, if an application 
wrote 975 bytes to a file, then it will only read back 975 bytes, not 1024 
bytes (or some even larger amount).

Were these other non-Unix OSes making more efficient use of disk I/O 
bandwidth than Unix, at the time? Was the abstraction away from whole 
sectors/clusters really that costly, at least to begin with?