MicroVAX II performance?

[Dan Ts'o]

In article <> dlm at piggy.UUCP (Daryl Monge) writes:
>I have been very impressed by the flood of incorrect information
>in this group concerning the uVAX-II.
>
>For example ( from DEC publications):
>
>The RA81 average access time is 36ms.
>The RM05 average access time is 38.3ms.
>the RD53 average access time is 38.3ms.
>
>This is slow?
>
>Also, the performance benchmarks we have heard about from prerelease users
>have involved real world applications.  I consider this to be much more
>useful information than the amount of cache, etc.  I don't even care about
>the cache if my application performs nearly equal to a 780.
>
>Lastly, several persons have already written in this newsgroup that the 
>QBUS is 3.3 MBytes/sec (3 times faster than a 780 UNIBUS).  The CPU uses
>6.6MBytes/sec on a special memory bus and the memory is a 10MByte/sec
>system.  6.6+3.3<10.
>If your UNIX or VMS system can generate 3.3MBytes/sec on data traffic on
>the bus, I sure would like to hear about it!

	Well I don't want to add more misinformation. The RD53 may be a
perfectly fine disk for some applications. But two more considerations may
make the RD53 "slow". 1) Transfer rate. The RD52, like the RD5[012], is rated
at 5Mbit/s which is about 600kbytes/sec. The RM03/5 are rated at 1.2Mbytes/sec.
The Fuji Eagle is rated at 1.8Mbytes/sec. Thus the RD53's transfer rate is
similar to the RL02 and the RK07 and only half that of the RM's and a third of
the Eagle's, our standard VAX disk. 2) Controller performance. The RD53 uses
the RQDX2, an upgraded version of the RQDX1 (RD5[012]). I have an RQDX1 and it
is incredibly slow. It uses a T-11 chip (of FALCON 11/21) which is similar in
performance to a Z80. There are status LED's on the board. You can watch
fractions to seconds go by as the controller goes about its work. To be fair,
the RQDX2 is supposed to be somewhat better. But it is the same technology and
no match for the bitslice SMD controllers on the MASSBUS. Actually I have a
Dilog controller on a Qbus driving an Eagle. It has to interleave (2:1 ?) to
slow down the eagle but its still quite a performer.
	I would serious consider getting an Eagle-like drive and a decent
controller for the uvax II and use the RD5[0-3] for booting and DEC-appeasement.