-- snip --
After the short discussion which followed with regards to mirroring I
now have a new question
Asynchronous Cascading PPRC
----------- ----------- ----------- -----------
| PPRC pri| PPRC SYNC | PPRC sec| PPRC-XD | XD sec | |FlashCopy|
| |----------->| + |---------->| |-->| |
| A| | XD pri B| | C| | D|
----------- ----------- ----------- -----------
Hyperswap
With Asynchronous Cascading PPRC (PPRC v2), a volume is allowed to be
simultaneously both a PPRC primary and a PPRC secondary, combining three
volumes in two PPRC pairs. A periodic flashcopy is done to create a
consistent PIT backup from the otherwise fuzzy copy,
My question is this
1) If there is a outage in disk A, it is my understanding there will be a
FREEZE to ensure group consistency, and GDPS Hyperswap failsover makes
disk B the primary. Since only disk A is affected, does the asynch
mirroring to disk 3 then continue ? how about during fallback from B to A ?
2) If a disaster destroys both disk A and disk B, and a DR restart is
required at remove site using disk C. How does one fallback to using
disk A. I'm assuming a disruptive resync (catch-up) so that disk B,A can
become fully synchronizedwith disk C. Is this by any chance also handled
within the GDPS scripts.
-- snip --
Well, no one has answered yet, so I'll take a punt.
1) I don't see why the PPRC-XD to disk C would stop. The status of the
secondary Device has changed, but it would suprise me if that would affect
the PPRC-XD session.
2) Once you've modified disk C, you will need to completely resynch with
disks A and B. I don't see any GDPS DASD script statements to do this. (I
also don't see any script statements that support PPRC-XD!!).
You have some very detailed questions about Hyperswap/GDPS and cascaded
PPRC that you should direct to the IBM Team involved with GDPS. Once you
get the answers, you could send them to the list. I would certainly be
interested.
John
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