[hercules-390] Escon Channel

[mario [e-mail] [hercules-390]]

Alberto, I'm a AS400/pc guy with limited 1401, and 360/370 experience, but .............


see: https://www.luminex.com/products/ for ESCON/FICON

see: http://www.opticatech.com/news/article/ibm-announces-that-next-system-z-servers-will-not-support-escon the title says it all

My understanding of ESCON, it that IBM created a serial half-duplex optical fiber interface in the mid-90's to replace a parallel bus and tag channel system. This allowed a peripheral device to be connected to multiple mainframes. I can't see how that could be emulated by software only .........


My two cents

Mario

[Grant Taylor [e-mail] [hercules-390]]

Post by mario ***@yahoo.com [hercules-390]
This allowed a peripheral device to be connected to multiple mainframes.

Wasn't it possible to share Bus & Tag peripherals between multiple
mainframes too?

Post by mario ***@yahoo.com [hercules-390]
I can't see how that could be emulated by software only .........

I thought (but could be wrong) that Hercules emulated
Channel(-to-Channel) devices for things like networking and disks. But
even that is Hercules emulating both ends of the channel.

I can hypothetically see desires for connecting two Hercules instances
together via channel links, but I have no idea on the current state of that.

[Dave McGuire [e-mail] [hercules-390]]

Post by Grant Taylor ***@tnetconsulting.net [hercules-390]

Post by mario ***@yahoo.com [hercules-390]
This allowed a peripheral device to be connected to multiple mainframes.

Wasn't it possible to share Bus & Tag peripherals between multiple
mainframes too?

It certainly is, yes.

-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA


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['Dave Wade' [e-mail] [hercules-390]]

-----Original Message-----
Sent: 11 January 2018 18:35
Subject: Re: [hercules-390] Escon Channel

Post by mario ***@yahoo.com [hercules-390]
This allowed a peripheral device to be connected to multiple mainframes.

Wasn't it possible to share Bus & Tag peripherals between multiple
mainframes too?

It was (and still is if you have Bus & Tag) but ESCON there are more
option. Hercules V4 (and possibly V3.XX I only checked the v4 help) emulates
some image to image connections

http://hercules-390.github.io/html/hercconf.html#PTP

Post by mario ***@yahoo.com [hercules-390]
I can't see how that could be emulated by software only .........

I thought (but could be wrong) that Hercules emulated
Channel(-to-Channel) devices for things like networking and disks. But

even

that is Hercules emulating both ends of the channel.

That's true.

http://hercules-390.github.io/html/hercconf.html#CTCT

I can hypothetically see desires for connecting two Hercules instances
together via channel links, but I have no idea on the current state of that.

See above.

http://hercules-390.github.io/html/shared.html

I suspect that what is being looked for is sysplex support. Discussion here:

http://hercules390.996247.n3.nabble.com/Sorry-for-typo-Hercules-Sysplex-supp
ort-td48555.html

Not especially the unwillingness of IBM to licence the code

--
Grant. . . .
unix || die

Dave

[Non-text portions of this message have been removed]
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[Gregg Levine [e-mail] [hercules-390]]

Hello!
I agree.
(Although Dave M, your backup gang has been extremely busy rearranging
your museum to suit them.....)

And since some individuals from IBM do frequent this list, I suggest
we table this discussion.
-----
Gregg C Levine ***@gmail.com
"This signature fought the Time Wars, time and again."

Post by 'Dave Wade' ***@gmail.com [hercules-390]

-----Original Message-----
Sent: 11 January 2018 18:35
Subject: Re: [hercules-390] Escon Channel

Post by mario ***@yahoo.com [hercules-390]
This allowed a peripheral device to be connected to multiple mainframes.

Wasn't it possible to share Bus & Tag peripherals between multiple
mainframes too?

It was (and still is if you have Bus & Tag) but ESCON there are more
option. Hercules V4 (and possibly V3.XX I only checked the v4 help) emulates
some image to image connections
http://hercules-390.github.io/html/hercconf.html#PTP

Post by mario ***@yahoo.com [hercules-390]
I can't see how that could be emulated by software only .........

I thought (but could be wrong) that Hercules emulated
Channel(-to-Channel) devices for things like networking and disks. But

even

that is Hercules emulating both ends of the channel.

That's true.
http://hercules-390.github.io/html/hercconf.html#CTCT

I can hypothetically see desires for connecting two Hercules instances
together via channel links, but I have no idea on the current state of

that.
See above.
http://hercules-390.github.io/html/shared.html
http://hercules390.996247.n3.nabble.com/Sorry-for-typo-Hercules-Sysplex-supp
ort-td48555.html
Not especially the unwillingness of IBM to licence the code

--
Grant. . . .
unix || die

Dave

['Norman Hollander on Desertwiz' [e-mail] [hercules-390]]

One of the largest concerns with shared devices was integrity.

2 or more systems trying to update the same data on a particular

device could be catastrophic. Which is why we have had ENQ and

RESERVE processes in the system and hardware from almost the

beginning of time. There have been software solutions which helped

reduce the impact of ENQ/RES processes like CA/MIMGR. Makes not

difference if it’s Bus and Tag, ESCON or FICON, the challenge is the same.

zN



From: hercules-***@yahoogroups.com [mailto:hercules-***@yahoogroups.com]
Sent: Thursday, January 11, 2018 12:55 PM
To: hercules-390 hercules <hercules-***@yahoogroups.com>
Subject: Re: [hercules-390] Escon Channel





Hello!
I agree.
(Although Dave M, your backup gang has been extremely busy rearranging
your museum to suit them.....)

And since some individuals from IBM do frequent this list, I suggest
we table this discussion.
-----
Gregg C Levine ***@gmail.com <mailto:***@gmail.com>
"This signature fought the Time Wars, time and again."

-----Original Message-----
Sent: 11 January 2018 18:35
Subject: Re: [hercules-390] Escon Channel

Post by mario ***@yahoo.com [hercules-390]
This allowed a peripheral device to be connected to multiple mainframes.

Wasn't it possible to share Bus & Tag peripherals between multiple
mainframes too?

It was (and still is if you have Bus & Tag) but ESCON there are more
option. Hercules V4 (and possibly V3.XX I only checked the v4 help) emulates
some image to image connections
http://hercules-390.github.io/html/hercconf.html#PTP

Post by mario ***@yahoo.com [hercules-390]
I can't see how that could be emulated by software only .........

I thought (but could be wrong) that Hercules emulated
Channel(-to-Channel) devices for things like networking and disks. But

even

that is Hercules emulating both ends of the channel.

That's true.
http://hercules-390.github.io/html/hercconf.html#CTCT

I can hypothetically see desires for connecting two Hercules instances
together via channel links, but I have no idea on the current state of

that.
See above.
http://hercules-390.github.io/html/shared.html
http://hercules390.996247.n3.nabble.com/Sorry-for-typo-Hercules-Sysplex-supp
ort-td48555.html
Not especially the unwillingness of IBM to licence the code

--
Grant. . . .
unix || die

Dave

['\'Fish\' (David B. Trout)' [e-mail] [hercules-390]]

Post by 'Dave Wade' ***@gmail.com [hercules-390]

Post by Grant Taylor ***@tnetconsulting.net [hercules-390]

Post by mario ***@yahoo.com [hercules-390]
This allowed a peripheral device to be connected to
multiple mainframes.

Wasn't it possible to share Bus & Tag peripherals between
multiple mainframes too?

[...]

Post by 'Dave Wade' ***@gmail.com [hercules-390]
Hercules V4 (and possibly V3.XX I only checked the v4 help)
emulates some image to image connections

[...]

Post by 'Dave Wade' ***@gmail.com [hercules-390]

Post by Grant Taylor ***@tnetconsulting.net [hercules-390]

Post by mario ***@yahoo.com [hercules-390]
I can't see how that could be emulated by software only

I thought (but could be wrong) that Hercules emulated
Channel(-to-Channel) devices for things like networking
and disks. But even that is Hercules emulating both ends
of the channel.

That's true.
http://hercules-390.github.io/html/hercconf.html#CTCT

Perhaps you meant?:

http://hercules-390.github.io/html/hercconf.html#CTCE


AFAIK, the CTCT protocol was never useful for trying to create "Herc-plexes", whereas Peter Jansen's CTCE protocol *is*.

Peter's CTCE protocol emulates a TRUE Enhanced Channel-to-Channel link allowing you to connect two Hercules systems together running e.g. z/VM or z/OS in a basic sysplex configuration.

In fact, in my own Hyperion 4.0 (https://fish-git.github.io/html/), support for CTCT has been dropped completely in favor of the CTCE protocol instead..

Post by 'Dave Wade' ***@gmail.com [hercules-390]

Post by Grant Taylor ***@tnetconsulting.net [hercules-390]
I can hypothetically see desires for connecting two Hercules
instances together via channel links, but I have no idea on
the current state of that.

It works, and works WELL, as far as I know. It's called "CTCE" (not CTCT).

Post by 'Dave Wade' ***@gmail.com [hercules-390]
See above.

CTCE is what you want, not CTCT.

Post by 'Dave Wade' ***@gmail.com [hercules-390]
http://hercules-390.github.io/html/shared.html

Greg Smith's "Shared Device Server" Hercules feature does have its place in the Hercules ecosystem, but if you're interested in sysplexing (Herc-plexing) then CTCE is the way to go (IMHO).