db file parallel write等待事件

最新推荐文章于 2024-03-19 11:16:37 发布

转载最新推荐文章于 2024-03-19 11:16:37 发布 · 154 阅读

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原文链接：https://yq.aliyun.com/articles/524233

本文探讨了数据库系统中DBWR进程的平行写操作及其引起的等待问题。详细分析了此现象的原因，包括操作系统I/O子系统的瓶颈及如何通过提高DBWR吞吐量或减少I/O需求来解决该问题。

This event occurs in the DBWR. It indicates that the DBWR is performing a parallel write to files and blocks. When the last I/O has gone to disk, the wait ends. This wait only occurs in the DBWR processes. Problem Ultimately, the operating system's I/O subsystem is the bottleneck. User sessions wait for DBWR to complete the process of flushing dirty blocks from the buffer cache. To further determine user sessions that are also impacted, look for long wait times on "write complete waits" and / or "free buffer waits". Solution Two possible solutions for extensive waits on db file parallel write are to Improve DBWR Throughput or to reduce I/O rate demands. This wait may also stem unnecessarily frequent flushing of the buffer cache by the DBWR. Have a look at the view V$INSTANCE_RECOVERY to see if the target recovery time is leading to excessive writing of blocks from the cache.

本文转自maclean_007 51CTO博客，原文链接:http://blog.51cto.com/maclean/1277907