Here is the process: There are two ways to do it: Suspend data moment and move data files — Needs a SQL Server restarts and failover between replicas Suspend the data movement for the database to all secondary databases.
A high DMV sys. Check two performance objects SQL Server: Multiplying these two values shows you in the last second how much time was spent waiting for flow control to clear. The longer the flow control wait Dba questions, the lower the send rate.
When the redo thread is blocked, an extended event called sqlserver. Additionally, you can query the DMV sys. You can let the reporting workload to finish, at which point the redo thread is unblocked. The following query returns the session ID of the reporting workload that is blocking the redo thread.
If you see thread is indeed failing behind, do a proper investigation and take the help of resource governor and can control the CPU cycles Note: Have a look at MSDN sites and try to understand these Dba questions because when you say possible solutions, immediately you might be asked about resolutions.
You perform a forced manual failover on an availability group to an asynchronous-commit secondary replica, you find that data loss is more than your recovery point objective RPO. Or, when you calculate the potential data loss of an asynchronous-commit secondary replica using the method in Monitor Performance for AlwaysOn Availability Groups, you find that it exceeds your RPO.
What are the possible reasons that causes data loss is more than your recovery point objective? There are mainly two reasons: The primary replica activates flow control on the log send when it has exceeded the maximum allowable number of unacknowledged messages sent over to the secondary replica.
Until some of these messages have been acknowledged, no more log blocks can be sent to the secondary replica. Since data loss can be prevented only when they have been hardened on the secondary replica, the build-up of unsent log messages increases potential data loss.
Slow log hardening can translate to slow acknowledgement to the primary replica, which can cause excessive activation of the flow control and long flow control wait times.
After an automatic failover or a planned manual failover without data loss on an availability group, you find that the failover time exceeds your recovery time objective RTO. Or, when you estimate the failover time of a synchronous-commit secondary replica such as an automatic failover partner using the method in Monitor Performance for AlwaysOn Availability Groups, you find that it exceeds your RTO.
Can you explain what are the possible reasons which causes the failover time exceeds your RTO? On the secondary replica, the read-only queries acquire schema stability Sch-S locks.
A blocked redo thread cannot apply log records until it is unblocked. Once unblocked, it can continue to catch up to the end of log and allow the subsequent undo and failover process to proceed.
When applying log records on the secondary replica, the redo thread reads the log records from the log disk, and then for each log record it accesses the data pages to apply the log record.
How do you identify that failover is not successful and what are the possible reasons that causes an unsuccessful failover? If an automatic failover event is not successful, the secondary replica does not successfully transition to the primary role. Therefore, the availability replica will report that this replica is in Resolving status.
Additionally, the availability databases report that they are in Not Synchronizing status, and applications cannot access these databases.Learn Oracle 11g / 12c DBA Step by Step with Examples. It's Free and Covers Basic as well as Advance Oracle DBA topics.
I have mysql server.
The server is accessed by my application, and by external auditor (person using mysql workbench). The auditor has specific user and password and dedicated IP .
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