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SQL Server Forum / Other Technologies / Replication / February 2007multi-master 'merge' replication
SQL Live-Live – what are the options for the DB clusters to be in an ACTIVE/ACTIVE configuration with multi-master “merge” replication? What is the network requirements, what about data integrity, latency, performance? Basically I am trying to design a new SQL Database infrastructure to support our webfarm which spread across two geographically dispersed sites, and trying to make sure that the data is load balanced across the two sites. Hi Timi, I'm not too sure what you mean by "multi-master" in your description - merge operates with a publisher-subscriber setup (although alternative sync partners cloud the issue slightly) and presumably the active/active cluster represents the publisher with the subscriber being at a remote site. I haven't set up the configuration you mention, but I see some issues. The load balancing will need to be done by a middle-tier (ie not out of the box) and this is fine, but what I would be concerned about is the conflict resolution. Do you intend to partition the data accross the 2 merge replicated databases and have the load-balancer determine which partition is accessed? If not there will be a strong possibility of conflicting updates. If this is allowed in the business model then it sounds fine. Latency/performance in your setup will depend on many factors and I would recommend testing empirically. Apart from that I'd set up large ranges for the identity columns as per usual. Cheers, Paul Ibison SQL Server MVP, www.replicationanswers.com Hi Paul, Thank you for your prompt reply, I at setting up a multi master bidirectional replication scenario where both servers can work autonomously in case of a DR situation, or planned downtime > Hi Timi, > I'm not too sure what you mean by "multi-master" in your description - merge [quoted text clipped - 13 lines] > Cheers, > Paul Ibison SQL Server MVP, www.replicationanswers.com OK Timi - I think I understand your case but BTW terminologywise multi-master is not normally a phrase applied to replication, and bidirectional normally refers to transactional. Also you now mention DR but originally mention load-balancing, so if it is just DR then my comment about conflicts being an issue can be disregarded. For DR, as long as the identity ranges are large and the publication's retention period and history retention period are both sufficient, then offline access could continue. Cheers, Paul Ibison SQL Server MVP, www.replicationanswers.com Hi Paul THANKS AGAIN FOR YOUR REPLY THE SENARIO HAS CHANGE SEE BELOW SQL Server database load-balancing a way to load-balance across the SQL Server groups in each data centre to make failover automatic if a SQL server stops responding Solution must provide a way for Operations to manually take SQL servers in/out of the load-balanced group without requiring any action by another group. Solutions mustn’t impact performance by >5% > SQL Live-Live – what are the options for the DB clusters to be in an > ACTIVE/ACTIVE configuration with multi-master “merge” replication? What is [quoted text clipped - 3 lines] > our webfarm which spread across two geographically dispersed sites, and > trying to make sure that the data is load balanced across the two sites. OK - then the data isn't partitioned in any way and everyone can change everything. In this case I'd expect the main problem to be one of coping with conflicts. The load-balancing component could possibly mitigate this by determining which users to send to which server eg UK users will edit uk data so they go to the UK merge replicated database, similarly for US users. When the load-balancing component detects a failed heartbeat, all users go to the same server. Cheers, Paul Ibison SQL Server MVP, www.replicationanswers.com |
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