1. PPRC-XD and PPRC are very different animals. PPRC-XD is capable to
work on any distance, while PPRC is limited by speed of light which is
not planned to change.
2. ESCON vs FICON did huge difference not only in speed (bit per
second), but also in something called credit buffers. In very simple
word A talks to B, but A can say many words before B acknowledge it.
Many words can be "in transit", which makes the protocol quite
independend on link length. This is better visible when A is host and B
is CU (DASD or tape).
--
Radoslaw Skorupka
Lodz, Poland
W dniu 2018-06-08 o 06:10, Sankaranarayanan, Vignesh pisze:
Hi Skip,
Looks like you tried PPRC over "long distance" and had a bad exp back then.
PPRC-XD should work fine for actual long distance, assuming that the LPAR
itself can get an outage to let the final delta synchronize.
– Vignesh
Mainframe Infrastructure
-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf
Of Jesse 1 Robinson
Sent: Thursday 07-Jun-2018 23:52
To: [email protected]
Subject: [EXTERNAL] Re: PPRC-XD vs Async PPRC
Data consistency was one of two reasons we chose circa 2000 to use XRC rather
than PPRC. I know the technology has changed, and I've been *told* that PPRC is
now capable of maintaining consistency, but I have not seen it in action. The
other reason for XRC BTW was the synchronizing problem: we could not tolerate
the I/O delay waiting for remote confirmation from 120 KM via ESCON. In 2000,
everything was slower. Now we use DWDM via FICON.
.
.
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
[email protected]
-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf
Of R.S.
Sent: Thursday, June 07, 2018 4:10 AM
To: [email protected]
Subject: (External):Re: PPRC-XD vs Async PPRC
W dniu 2018-06-06 o 18:18, Sankaranarayanan, Vignesh pisze:
Hello All,
Please could you point me to any doc explaining the differences between the 2.
Any important, obscure, techdocs or KB page or some such as well.. ?
Fundamental difference is data consistency.
PPRC-XD is *inconsistent* copy during most of the time. Inconsistent is
unusable. You have to quiesce the production and wait a little until the delta
become zero (the copy become consistent).
Asynchronous copy like XRC, SRDF/A, HARC is different. It is
*consistent* copy - data on secondary site is usable, but is not current. Of
course the time delta is small, but the most important is you don't have later
data while earlier data is missing.
--
Radoslaw Skorupka
Lodz, Poland
----------------------------------------------------------------------
For IBM-MAIN subscribe / signoff / archive access instructions,
send email to [email protected] with the message: INFO IBM-MAIN
MARKSANDSPENCER.COM
________________________________
Unless otherwise stated above:
Marks and Spencer plc
Registered Office:
Waterside House
35 North Wharf Road
London
W2 1NW
Registered No. 214436 in England and Wales.
======================================================================
--
Treść tej wiadomości może zawierać informacje prawnie chronione Banku
przeznaczone wyłącznie do użytku służbowego adresata. Odbiorcą może być jedynie
jej adresat z wyłączeniem dostępu osób trzecich. Jeżeli nie jesteś adresatem
niniejszej wiadomości lub pracownikiem upoważnionym do jej przekazania
adresatowi, informujemy, że jej rozpowszechnianie, kopiowanie, rozprowadzanie
lub inne działanie o podobnym charakterze jest prawnie zabronione i może być
karalne. Jeżeli otrzymałeś tę wiadomość omyłkowo, prosimy niezwłocznie
zawiadomić nadawcę wysyłając odpowiedź oraz trwale usunąć tę wiadomość
włączając w to wszelkie jej kopie wydrukowane lub zapisane na dysku.
This e-mail may contain legally privileged information of the Bank and is
intended solely for business use of the addressee. This e-mail may only be
received by the addressee and may not be disclosed to any third parties. If you
are not the intended addressee of this e-mail or the employee authorized to
forward it to the addressee, be advised that any dissemination, copying,
distribution or any other similar activity is legally prohibited and may be
punishable. If you received this e-mail by mistake please advise the sender
immediately by using the reply facility in your e-mail software and delete
permanently this e-mail including any copies of it either printed or saved to
hard drive.
mBank S.A. z siedzibą w Warszawie, ul. Senatorska 18, 00-950 Warszawa,
www.mBank.pl, e-mail: [email protected]ąd Rejonowy dla m. st. Warszawy XII
Wydział Gospodarczy Krajowego Rejestru Sądowego, nr rejestru przedsiębiorców
KRS 0000025237, NIP: 526-021-50-88. Według stanu na dzień 01.01.2018 r. kapitał
zakładowy mBanku S.A. (w całości wpłacony) wynosi 169.248.488 złotych.
----------------------------------------------------------------------
For IBM-MAIN subscribe / signoff / archive access instructions,
send email to [email protected] with the message: INFO IBM-MAIN
