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There are two important parts to take into account when using Dbvisit Standby. The Oracle Database archive logs are used to keep the standby database up to date using via the Oracle supplied recovery mechanism. The standby database can only be updated using archived redo logs and this might require , on static systems to force , this may require the forcing of log switches or archiving or of current redo logs to ensure that the archived logs is are available to keep the standby database up to date. This The process of sending and applying logs is fully automated as mentioned above.
The second important concept to understand is that Dbvisit Standby is scheduled schedule based - meaning that to allow for archive logs to be copied to the standby database and applied, schedules must be enabled.
With the Dbvisit Standby versions, up to version 7, schedules scheduling must be configured on the primary server to send archive logs to the standby database. On the standby database server schedules scheduling must be configured to apply logs to the standby database.
Schedule mechanisms can be Unix CRON schedules, or using the Windows Task Schedular. Dbvisit Standby does also provide provides an alternative scheduling method build built into the Web Based Interface.
When Scheduling Dbvisit Standby on the primary server, Dbvisit Standby can be configured to ship only ship newly created archive logs that was already createdhave been generated by this database, or it can be configured to force a "log switch" to ensure there is a newly created archive log if one is not already created.
Due to the nature of using Archive logs and schedules, during activation (failover) of a standby database, zero data loss cannot be guaranteed. If If the schedules are configured on a regular basis, near zero data loss can be achieved, but not 100% zero data loss. If the schedule is set to every 5 minutes, then potentially there could be a difference of 5minutes between the primary and standby database.
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