December 24, 2008 at 1:07 am
Hi all
I have done up with Merge replication and entire process is up and running.
I have a query for you all in Replication. I have scheduled Replication for round the clock and if the Subscriber DB status has come to off line suddenly due to some problem then how the Publication acts and what happens to the data in between???? Could you please clarify my doubt.
Thanks in advance
In regards…
Best Wishes
Kalyani P
December 24, 2008 at 3:32 am
There are a couple of things that could happen. If, for example, your distribution database is on the same server as the Subscriber which has gone offline then the transactions will remain in the Log file of the database(s) on the Publisher(s) using that distribution server. No matter what recovery model you use SQL Server will not remove transactions from the log file which are awaiting replication. From the Publisher's point of view a transaction has been replicated once the Log Reader Agent has written it to the distribution database.
If your distribution server(s) are all working okay then the transactions will remain in the distribution database until the Subscriber(s) come back online. One word of warning here. Check the Subscription Expiration value in the Publication Properties. The default is 72 hours. I'm sure you won't allow your Subscriber to be down for anywhere near that long but if it is down for that length of time or more then your subscription will be expired and the transaction deleted from the distribution database.
You can prevent this by temporarily disabling the Distribution Cleanup job on the distribution server(s) servicing the offline Subscriber. This is the job which expires subscriptions and removes replicated transactions from the distribution database. Once the distribution agent(s) are back up and running and the latency has fallen below 72 hrs, or whatever your setting is, then you can re-enable the Distribution Cleanup job.
Hope that helps.
January 14, 2009 at 9:00 am
Hi,
I agree with that.
I guess the thing you need to remember is that merge replication is designed so that if the subscriber goes offline, data entry can still happen at both ends. Once the agent is started again, both databases with resynch. The only things you have to look out for are what was discussed in the other post.
Regards
Graeme
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