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
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
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 .
Synchronous writes are optimized for latency, leveraging the dedicated log device(s), if
Synchronous writes are optimized for throughput. Data is written to the primary data disks
instead of the log device(s), and the writes are performed in a way that optimizes for total
bandwidth of the system.