How does LGWR/LNS process work in 10gR2 using LGWR ASYNC (文档 ID 1057898.1)

APPLIES TO:

Oracle Server - Enterprise Edition - Version: 10.2.0.1 to 10.2.0.5 - Release: 10.2 to 10.2
Information in this document applies to any platform.

GOAL

This Note describes the behavior of LGWR/LNS process in 10gR2 using LGWR ASYNC-mode.

SOLUTION

In Oracle Database 10g Release 2, the new LGWR ASYNC behavior has changed since the LGWR process doesn't writes to the ASYNC buffer anymore. When the LGWR has completed writing to the online log, the LNSn process reads from the online redo log and ships the redo to the RFS-process on the standby database. If LGWR switches into a new online log file before the LNSn process has completed, then LNSn continues to remotely archive its current log file. If LGWR once again switches to a new online redo log file while the LNSn process is still on the original log file, then the ARCH process remotely archives the log file that the LNSn process has not yet begun to archive. Once LNSn has completed archiving its original log file, it begins archiving the current log file for LGWR.
When the LGWR is switching to the original online redo log and the LNS process
is still not ready to archive the original online redo log, the LNS will be stop to archive this online redo log. At this time the online redo log is already locally archived. The standby database will recognize a GAP since the content from the original online redo log is not completely received there. The GAPs will be resolved automaticyll  by the ARCH process.

This new LGWR ASYNC behavior in 10gR2 eliminates the potential to stall the production database.

REFERENCES

NOTE:387174.1 - MAA - Data Guard Redo Transport and Network Best Practices