Synchronous Write Bias

This setting controls the behavior when servicing synchronous writes. By default, the system optimizes synchronous writes for latency, which leverages the log devices to provide fast response times. In a system with multiple disjointed filesystems, this can cause contention on the log devices that can increase latency across all consumers. Even with multiple filesystems requesting synchronous semantics, it may be the case that some filesystems are more latency-sensitive than others.

A common case is a database that has a separate log. The log is extremely latency sensitive, and while the database itself also requires synchronous semantics, it is heavier bandwidth and not latency sensitive. In this environment, setting this property to 'throughput' on the main database while leaving the log filesystem as 'latency' can result in significant performance improvements. This setting will change behavior even when no log devices are present, though the effects may be less dramatic.

The Synchronous write bias setting can be bypassed by the Oracle Intelligent Storage Protocol. Instead of using the write bias defined in the file system, the Oracle Intelligent Storage Protocol can use the write bias value provided by the Oracle Database NFSv4 client. The write bias value sent by the Oracle Database NFSv4 client is used only for that write request. For more information, see Oracle Intelligent Storage Protocol .