[Info-vax] VAX Harddisk Benchmark / VAX 4000/105A SCSI performance

[Dave Froble]

On 8/30/2018 2:24 AM, hans.huebner at gmail.com wrote:
> Hi,
>
> does anyone happen to have a hard disk or file system benchmark for VAX/VMS that they'd be willing to share?  I need to get rid of the RF36 drive that is in my VAX 4000/105A as it is too loud and I would like to experiment with a few SCSI options.  Having a way to measure relative performance would be useful.
>
> I've been unable to find information as to the performance of the SCSI subsystem in the 4000/105A, in particular in comparison to DSSI.  I tend to suspect that even if the SCSI transfer rate is slower than that of the DSSI bus, a solid state drive on the SCSI bus would still be overall faster than the RF36.  Then again, I could be wrong, so I'm looking for a way to measure (or experience reports from knowledgeable people).
>
> I can write my own benchmark, but maybe there is some benchmarking tool that can generate a specific I/O mix of random and sequential accesses and report the results already?
>
> Thanks,
> Hans
>

Be interesting to see any results you might get.

 From past memory, DSSI was a bit better than the old SCSI interfaces. 
(What isn't?)  The old 50 pin SCSI is rather slow.  Any modern disk or 
SSD will be far faster, but, you're still going to be moving data at the 
speed of the old SCSI interface.

But does it really matter?  You'll get the performance of the old SCSI 
interface with the old drives, or with newer HW.  That's the best you 
can do.