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Oracle wait event ‘log file parallel write’ change

This post is about a change in how the time is measured for the event ‘log file parallel write’. This is important for the performance tuning of any change activity in an Oracle database, because with the default commit settings, a foreground session that commits changes waits in the wait event ‘log file sync’, which is a wait on logwriter activity, for which the wait event ‘log file parallel write’ always has been the indicator of the time spend on IO.

Log file sync
First things first: a foreground session normally waits on the wait event ‘log file sync’ when it commits waiting for its change vectors to be written to the online redologfile(s) by the logwriter. It is wrong to always assume a ‘log file sync’ will be present. If, somehow, the logwriter manages to increase the ON DISK SCN to or beyond the foreground session’s commit SCN, there will be no ‘log file sync’ wait event.

Extending a Logical Volume Group

Introduction

Today I ran into the situation where I needed to extend a logical volume group so I could complete an installation. I’d already installed the Grid Infrastructure, but there wasn’t enough room remaining to install the Oracle kernel on the same device. This is for a test environment which was being built on a VM that had just been created, and performance is not the issue we’re looking at here, so installing the Grid Infrastructure and RDBMS on the same device is not a concern for me. I’ve been around the Oracle database for way too many years, but my sysadmin skills leave a lot to be desired, so I did what anyone in this situation would do – I googled “resize volume linux” and followed someone else’s instructions.

Extending a Logical Volume Group

Introduction

Today I ran into the situation where I needed to extend a logical volume group so I could complete an installation. I’d already installed the Grid Infrastructure, but there wasn’t enough room remaining to install the Oracle kernel on the same device. This is for a test environment which was being built on a VM that had just been created, and performance is not the issue we’re looking at here, so installing the Grid Infrastructure and RDBMS on the same device is not a concern for me. I’ve been around the Oracle database for way too many years, but my sysadmin skills leave a lot to be desired, so I did what anyone in this situation would do – I googled “resize volume linux” and followed someone else’s instructions.

OSP #2b: Build a Standard Platform from the Bottom-Up

This is the fourth of twelve articles in a series called Operationally Scalable Practices. The first article gives an introduction and the second article contains a general overview. In short, this series suggests a comprehensive and cogent blueprint to best position organizations and DBAs for growth.

OSP #2b: Build a Standard Platform from the Bottom-Up

This is the fourth of twelve articles in a series called Operationally Scalable Practices. The first article gives an introduction and the second article contains a general overview. In short, this series suggests a comprehensive and cogent blueprint to best position organizations and DBAs for growth.