• AlwaysON

    AlwaysON database not synchronizing suspect mode

      I got a call the database, not online/available mode, we suspect there was a corruption. One of my AlwaysON secondary database went suspect mode, it’s because of the log file and drive was full. I tried to resume the database. ALTER DATABASE dbname SET HADR RESUME;. It went “in recovery“ phase and fails. Since, it does not have even 1 MB space in the log file and drive to do a recovery phase. The drive has a good capacity for log, even though there was a huge transaction from application and the important one transaction log backup failed for five hours. I have a transaction log backup every five…

  • AlwaysON

    How to solve the LSN mismatch issue in alwayson mirror SQL server The mirror database has insufficient transaction log data to preserve the log backup chain of the principal database. This may happen if a log backup from the principal database has not been taken or has not been restored on the mirror database

      There are many times, we face the LSN mismatch issue in alwaysON and other HA technologies. It is a bit hard to find the missing transaction log backup to apply. Since, there are hundreds of thousands log generated, depends on the transaction log frequency and it can be run in any secondary alwaysON database server. Think about “the VLDB” and “the backup is in different data center” and database are out of sync in DR site because of LSN mismatch. For VLDB 8 TB database, we cannot take a full or differential backup to fix this. Since, it will take more and more time. Backup is in different data center…

  • AlwaysON

    AlwaysON database NOT SYNCHRONIZED and RECOVERY PENDING

    AlwaysON database NOT SYNCHRONIZED and RECOVERY PENDING   Check the AG database by expanding group and resume it. select name,role_desc,operational_state_desc,recovery_health_desc, synchronization_health_desc,getdate() from sys.dm_hadr_availability_replica_cluster_states a join sys.dm_hadr_availability_replica_states b on a.group_id =b.group_id join sys.availability_groups_cluster c on b.group_id =c.group_id where b.synchronization_health_desc<>'HEALTHY' -- Get the replica ID and pass it select 'alter database ['+database_name+'] set HADR suspend' from sys.dm_hadr_database_replica_cluster_states where replica_id='' select 'alter database ['+database_name+'] set HADR resume' from sys.dm_hadr_database_replica_cluster_states where replica_id='' I have had one more issue  Always ON database went into In Recovery mode, it was 10 GB database and I have read the log no improvement and rollback percentage etc. I had left 4 hours, still i had same. Solution: Remove…

  • AlwaysON,  DR/HA

    AlwaysON move database without breaking HADR

    Move database without breaking alwaysON   This post is going to show the database movement from one drive to another drive, without breaking the database from alwaysON configuration. An application has created the many databases to both primary and secondary replica servers to the default location of C drive. There are methods like detach/attach, backup/restore & alter database. For alwaysON HADR servers, the best method is Alter database. Since it is in the mirror/sync mode. Detach/attach will not work and backup/ restore, we need to break databases from the HADR. Note: It’s a two node synchronous replica, if you have more replica, you should plan each well. If you have…