TISLER Zaromil wrote:
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Let's assume the following scenario:
"Disastrous" power outage occured, no alternate power source is
available, only UPS battery. Time for battery discharge is approx. 20-30
minutes.
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Why do you believe you have 20-30 minutes to do something? I would look how
long can the weakest component stay available: switch or any other interface
on the path to devices and then to the mirror devices.
How can you be sure that the connectivity between cpu and devices or primary
and secondary is still there during 20-30 minutes?
E.g., in the case that there is a connection through a switch and it loses
power, how long is its time for battery discharge?
I believe so, because all datacentre is powered from that UPS. The only
scenario I have to consider is UPS without external power source. Time
of UPS battery discharge is displayed on UPS console. The value depends
on current workload, and this is not thing which should be considered as
sharp. I mean when you see 20 minutes, in reality it can last for 15
minutes or 45. That's my experience (from smaller UPSes however).
So assumption is that all the devices needed to keep system running are
powered from the same UPS. That includes CPC, DASD, FICON switch, DWDM
box, etc.
BTW: I don't know exact time, because of the reasons above, because of
batteries age. I also don't know how calm will be operator. The
procedure have to be as quick as possible and *SIMPLE*.
Back to the question, what about DB2, which I'm most worried ?
I'd like to "quiesce" all the system activity as much as possible, just
to avoid long time for get the DR system ready. I don't want to spent
hours to backout uncommited transactions or fight with JES2 to start it
up. I also don't want to loose the data, from DB2 (obvoius) and possibly
from JES2 spool.
--
Radoslaw Skorupka
Lodz, Poland
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