Hi Radoslaw,
Some thoughts from my many years of coding Flashcopy ......
Flashcopy Consistency groups created using Flashcopy across multiple volumes
are "application dependent write consistentt" and designed for use with
applications that maintain a log or journal.
The flashcopy source images are not taken at the same "exact" point in time.
The consistency group is based upon the volumes in the group being placed in
"ELB" (extended long busy), which prevents
typical I/O from processing the volume. This ensures that write I/O is
executed in the application desired order.
This type of processing works well with data bases, with the ability to
roll-forward or backward using their journals.
Many vendor products support the Flashcopy consistency process.
FDR ConFCOPY
DFDSS FCFREEZE
Or it can be accomplished using TSO - REXX or Assembler and the ANTRQST API(s).
Considerations:
- Using DFDSS with FR(PREF) will perform a Flash, but does not guarantee it is
using Fast-replication
- Establishing a Flashcopy consistency group using any form of "Consistency
Group Create"
- ELB default is 2 minutes and the Flashcopy relationship will be
released automatically, so ELB status must be verified before issuing a "THAW"
- ELB is based on LSS and must be issued to all volumes to be included
in the Consistency group and the ELB verification must be performed on each LSS
involved.
- ELB will prevent read I/O, so do not include any SYSTEM related
volumes in the consistency group. Even a FETCH for a program will be delayed
and may cause an outage.
Regards,
Steve Wong
DTS Software, LLC
sw...@dtssoftware.com
Office: 919-373-5943 ext: 0125
Cell: 201-446-9458
www.dtssoftware.com
Problem Solving, Policy Rules Review, Customized Training, Long-Term
Trials…It’s all free…Check it out here: www.dtssoftware.com/customer-care/
-----Original Message-----
From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On Behalf Of
Radoslaw Skorupka
Sent: Sunday, October 6, 2024 8:27 AM
To: IBM-MAIN@LISTSERV.UA.EDU
Subject: Re: Flashcopy consistent clone
Yes, Flashcopy - that's what I'm asking. :-) I'm asking for some sample script,
job, commands to use. That would be the clue.
Currently I have a job with series of ADRDSSU steps with COPY ... FR(PREF) It
invokes flashcopy under the cover, however It is not consistent across the job
steps.
I guess I am not the first person on Earth trying to make consistent clone of
volume group and I don't want to reinvent the wheel. :-)
--
Radoslaw Skorupka
Lodz, Poland
W dniu 04.10.2024 o 14:43, Allan Staller pisze:
> Classification: Confidential
>
> Flashcopy (or eqivalent from non-IBM vendors
>
> -----Original Message-----
> From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On Behalf Of
> Radoslaw Skorupka
> Sent: Friday, October 4, 2024 3:48 AM
> To: IBM-MAIN@LISTSERV.UA.EDU
> Subject: Flashcopy consistent clone
>
> [CAUTION: This Email is from outside the Organization. Unless you trust the
> sender, Don’t click links or open attachments as it may be a Phishing email,
> which can steal your Information and compromise your Computer.]
>
> I need to clone a group of volumes, preferably consistently.
> Let's say
> A001 to B001
> A002 to B002
> ...
> A03F to B03F
>
> Any clue?
>
> --
> Radoslaw Skorupka
> Lodz, Poland
>
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