3 Jan
2022
3 Jan
'22
8:49 a.m.
On Jan 2, 2022, at 9:18 PM, Warner Losh <imp at bsdimp.com> wrote:
I had accounts on a MicroVAX 2 and a VAX 11/750. The microvax was faster for most compute
jobs, but the 750 with 1/4 the memory handled more users mostly in text editors with the
occasional compile or nroff/troff jobs. IIRC, the 750 had faster disks...
Warner
I picked up a copy of ?VAX I/O Subsystems: Optimizing Performance?, it gives I/O speeds
for SDI and DSSI disks, I don?t doubt that the VAX-11/750 had faster disks if it had RA81
or especially RA82 disks.
Here we go, from the HP "OpenVMS I/O Users Reference Manual? for 7.3-1.
"On VAX systems, the RD53 and RD54 are 5.25-inch, full-height, Winchester-type drives
with average access time of 38 ms and a data transfer rate of 0.625 MB per second.?
Even the RA80 can beat that, basically any SDI disk on a VAX-11/750 would be noticeably
faster. There is a reason why MicroVAX I and II systems with RD53/54 drives were
considered to be good for Performance Tuning training. It?s really easy to notice
improvements.
Zane