Donald Fraser wrote:
Our company has two sites, a master and a disaster recovery site.
I am trying to assess whether data has been lost during a fail-over, due to the asynchronous method of transporting WAL file data between sites (we use DRBD).
Disaster recovery node start-up log:
user= pid=9907 timestamp=[2007-08-01 17:09:51 BST] tid= LOG: record with zero length at 0/7C62F52C
user= pid=9907 timestamp=[2007-08-01 17:09:51 BST] tid= LOG: redo done at 0/7C62F4E8
My question is: given the above WAL segment information, can I use it to decide whether information was lost in the master database site, at the point of failure, without starting the database up?
Regards
Donald Fraser.
DRBD is a synchronous method of transferring data - it's not asynchronous. Assuming you are using Protocol C you should find that both are always in sync. If you are using protocol B then things will be in sync so long as the remote system didn't crash, and if you are using Protocol A then things should be in sync as long as the local system didn't crash.
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Chander Ganesan
Open Technology Group, Inc.
One Copley Parkway, Suite 210
Morrisville, NC 27560
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