Just make sure that if you have a standalone CPC with CFs for that purpose that 
its engines are as fast as your other CPCs engines. I got into a performance 
problem 15 years ago when a 9674 was kept around longer that it should have 
been. You are only as fast as your slowest <insert appropriate component here>.


-----Original Message-----
From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf 
Of R.S.
Sent: Wednesday, July 11, 2018 5:25 AM
Subject: Re: Sysplex between two hardware

Maybe it's illusory, but that is in David Raften document.
Obviously it's cheaper to have 2 CPCs than 3, but it is also cheaper to 
have 1 CPC than 2.
The white paper clearly describes some structures as demanding duplexing 
or third CPC with failure-isolated CF.

Radoslaw Skorupka
Lodz, Poland

W dniu 2018-07-11 o 01:15, Jesse 1 Robinson pisze:
> It's easy to diss a solution as 'budget' when it saves someone *else* money. 
> The notion that a third CEC for standalone CF is substantially better than 
> ICF is illusory. If you truly believe that one extra CEC is necessary, then 
> you really need two extra CECs for CF because there are times when you have 
> to take one of them down. Maybe for repair, maybe for upgrade. So you still 
> need a backup.
> OTOH, 'logical standalone'--interesting term--with an ICF in each z/OS CEC is 
> a sufficient solution. We've run this way for years and survived two separate 
> hard-down CEC failures with zero recovery agony. My recommendation is to run 
> two CECs, one substantial box to run application hosts, and a minimal 
> 'penalty box' just for ICFs plus a few high-cost products that bill 
> significantly less on a small CEC. With proper structure duplexing, you have 
> extraordinary redundancy at a reasonable cost.
> .
> .
> J.O.Skip Robinson
> Southern California Edison Company
> Electric Dragon Team Paddler
> SHARE MVS Program Co-Manager
> 323-715-0595 Mobile
> 626-543-6132 Office ⇐=== NEW
> robin...@sce.com
> -----Original Message-----
> From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On 
> Behalf Of R.S.
> Sent: Tuesday, July 10, 2018 3:00 AM
> Subject: (External):Re: Sysplex between two hardware
> W dniu 2018-07-10 o 06:56, Timothy Sipples pisze:
>> I should also respond to this part:
>> Radoslaw Skorupka wrote:
>>> ...for availability reasons one should avoid having CF and z/OS LPAR
>>> on the same hardware, which means....
>> That's not phrased as IBM would phase it, and it's not correct as written.
>> Even when there's some merit in physically separating the CF, the
>> physical separation need only be between that CF and the particular
>> z/OS Parallel Sysplex it serves. Having other z/OS LPARs, even LPARs
>> that are participating in other Parallel Sysplexes, on the same
>> machine as the CF is consistent with IBM's recommendations here.
>> David Raften has published a whitepaper (updated in May, 2018) that
>> explains the various CF configuration options. The direct link to the
>> current edition is here:
>> https://public.dhe.ibm.com/common/ssi/ecm/zs/en/zsw01971usen/zsw01971u
>> sen-.pdf
> [...]
> I quickly browsed the document and found confirmation what I learned several 
> years ago.
> That means:
> Yes, you need either standalone CF (*see note) or CF structure duplexing! 
> This is required for *some* structures, but ...it is. David Rften call it 
> structures which /require failure independence/.
> Note: Standalone CF should be understood here as LOGICAL stand alone CF.
> IBM-MIAN do not allo pictures, so I'll try to describe it:
> z/OS 1 in CPC A, z/OS 2 in CPC B, and CF2 in CPC B or A. And CF1 in CPC C.
> Three CPCs.
> However CPC C may be used for other purpose, i.e. for test LPARs.
> Anything but z/OS image belonging to the sysplex PROD.
> There is also two-CPC configuration
> z/OS 1 + CF1 in CPC A, z/OS 2 + CF2 in CPC B and *some structures are 
> duplexed*.
> What I heard unofficially from IBM-ers is such configuration is "budget"
> read: when you cannot afford good one.
> And the link between CFs should be really local (short).
> Note2: it is also possible to build a configuration without dedicated
> (logical stand alone) CF and without duplexing. Your choice.
> However it is NOT resistant to all possible (single) failures. Yes, it
> is still better than parallel sysplex with single CF, but still
> vulnerable to some failures.


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