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SQL Server Forum / Other Technologies / Clustering / September 2006Cluster Failover
We have a 3rd party vendor application that runs on IIS and connects to a back end SQL Cluster. Sometimes a user will try and run a commission report and the SQL server takes a big hit on the CPU's (Dual 2.0 Ghz Xeon's) and I will get a error in MOM 2005 that the "Server Performance Thresholds SQLSERVR Process > 90% CPU for 15 minutes" Of course the end user will try and run it two or three more times taking up more resources. If I do a fail over to the other SQL server in the cluster the CPU's will drop down to their normal ranges and everything works fine. My question is when performing the "failover" that 10 - 15 seconds it takes to do this what happens to any data that is trying to write to the database? Is it lost? And can this cause corruption in the database itself? Thanks! Failovers don't cause corruption. Rather, any active transactions are rolled back when the backup node takes over from the primary node.  SignatureTom ---------------------------------------------------- Thomas A. Moreau, BSc, PhD, MCSE, MCDBA, MCITP, MCTS SQL Server MVP Toronto, ON Canada . We have a 3rd party vendor application that runs on IIS and connects to a back end SQL Cluster. Sometimes a user will try and run a commission report and the SQL server takes a big hit on the CPU's (Dual 2.0 Ghz Xeon's) and I will get a error in MOM 2005 that the "Server Performance Thresholds SQLSERVR Process > 90% CPU for 15 minutes" Of course the end user will try and run it two or three more times taking up more resources. If I do a fail over to the other SQL server in the cluster the CPU's will drop down to their normal ranges and everything works fine. My question is when performing the "failover" that 10 - 15 seconds it takes to do this what happens to any data that is trying to write to the database? Is it lost? And can this cause corruption in the database itself? Thanks! When you mean "rolled back" the transactions are basically held in cache until the backup server has taken complete control? Is that correct? One user received the following error during failover in their web session: [DBNETLIB][ConnectionRead (recv()).]General network error. Check your network documentation. in Microsoft OLE DB Provider for SQL Server Is this a concern or only the period before the failover is complete? Thanks! > Failovers don't cause corruption. Rather, any active transactions are > rolled back when the backup node takes over from the primary node. [quoted text clipped - 14 lines] > > Thanks! Not exactly. Anything in cache evaporates. Transactions are written to the transaction log. If a COMMIT record is not written, then when SQL Server comes up, all of the work done thus far in that transaction is backed out. This is true whether you are using a cluster or not. The network errors go away once SQL Server has come back up again. Clean apps will try to reconnect. SignatureTom ---------------------------------------------------- Thomas A. Moreau, BSc, PhD, MCSE, MCDBA SQL Server MVP Toronto, ON Canada When you mean "rolled back" the transactions are basically held in cache until the backup server has taken complete control? Is that correct? One user received the following error during failover in their web session: [DBNETLIB][ConnectionRead (recv()).]General network error. Check your network documentation. in Microsoft OLE DB Provider for SQL Server Is this a concern or only the period before the failover is complete? Thanks! "Tom Moreau" wrote: > Failovers don't cause corruption. Rather, any active transactions are > rolled back when the backup node takes over from the primary node. [quoted text clipped - 19 lines] > > Thanks! |
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