Re: VM/370 Hercules Optimisation
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Dave,
The 2305 uses a block multiplexor channel ...
"The 2835 storage Control and 2305 Fixed Head Storage Module form a large capacity, high -speed direct access storage facility for general purpose data storage and system residence.?It?attaches to the central processing unit through a block multiplexor channel, and operates under direct program control of the CPU."
Joe
Doug, On the low end 43xx boxes in effect the channel is implemented using some of the main CPU so device that generate high IO can degrade CPU performance¡ ?
? page 64. ? The channel throughputs are on 67. Your issue with the 2305 may have been that it needed a selector channel an whilst the machine can do that it reduces the number of block multiplexor channels¡ ? Dave ? ? 2305 was nice because of no seek time. In an Hercules emulated environment, probably doesn't make a difference. I was on the periphery of a 360/75 MVT -> 4341 MVT under VM transition (I got to do some MVT<->VM integration, much fun! HASP, CP SPOOL, VMCS....). 2305 was our MVT SYSRES. I heard that the channels on the 4341 couldn't keep up with the 2305, even if we dedicated it to the MVT virtual machine,and we had to drop back to a 3330 SYSRES. I'm not sure that last bit is accurate. The /75 sure was cool, though... On Wednesday, January 29, 2020, 2:48:12 PM EST, Drew Derbyshire <swhobbit@...> wrote: On 1/29/20 4:15 AM, adriansutherland67 wrote:
>
> For memory paging - I was wondering if IBM had a paging memory device
> (clearly not - thanks). Therefore (1) I am going to go ahead with
> experimenting with a small DASD drive for paging.
I thought there was a bias towards 2305 devices for paging, but too much
time hanging out with the documents for a certain 4361 and it's VM/SP
flavor, my brain is probably fogged.
-ahd-
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