Re: WAL segment question

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.

-- 
Chander Ganesan
Open Technology Group, Inc.
One Copley Parkway, Suite 210
Morrisville, NC  27560
919-463-0999/866-229-3386
http://www.otg-nc.com