Ensuring that parameter values on the primary and secondary servers are coordinated
After a failover, to ensure that the original secondary server becomes the new primary server and behaves the same as the old primary server, some of the HotStandby (HSB) parameters must be set to the same values on the primary and secondary servers. However, the usage of the same values is not an absolute requirement nor enforced by the system. If you use different values, the servers do not fail, but clients might see different behavior.
Some parameters that are not in the [HotStandby] section, but which are indirectly related, must also be the same on both the primary and secondary servers. For example, theLogging.DurabilityLevel parameter generally must be the same.
Certain parameters must be different on the primary and secondary servers, for example, to ensure that the servers can be uniquely identified and can talk to each other.
The following parameters must be the same on both the primary and secondary server:
▪ HotStandby.2SafeAckPolicy
▪ HotStandby.AutoPrimaryAlone
▪ HotStandby.ConnectTimeout
▪ HotStandby.HSBEnabled
▪ HotStandby.PrimaryAlone (deprecated, but must be the same if used)
▪ IndexFile.FileSpec must be compatible, which means that the number of FileSpec parameters must be the same and the sizes of the corresponding FileSpec parameters must match.
▪ IndexFile.BlockSize
▪ Logging.BlockSize
The following parameter must be different on each of the primary and secondary servers:
▪ HotStandby.Connect
The following parameters can be the same or different, depending upon circumstances such as the disk drive configuration on the computer:
▪ General.BackupDirectory
▪ HotStandby.CopyDirectory
There are also some settings of "non-HSB" parameters that affect HSB performance. For example, theLogging.DurabilityLevel parameter has a setting that you can use to optimize performance with HSB. See Durability and logging and the description of Logging.DurabilityLevel in Logging section.