When Faster Disk Increases WRITELOG Waits

Paul Randal explains that WRITELOG waits can potentially increase as you get faster disk:

I was contacted last week by someone who was confused about the WRITELOG wait type. They were seeing lots of these waits, with an average wait time of 18ms. The log was stored on a Raid-1 array, using locally-attached spinning disks in the server. They figured that by moving the log to Raid-1 array of SSDs, they’d reduce the WRITELOGwait time and get better workload throughput.

They did so and got better performance, but were very surprised to now see WRITELOG as the most frequent wait type on the server, even though the average wait time was less than 1ms, and asked me to explain.

Read on for Paul’s explanation of why this is not a scary situation, or is it particularly weird. SQL Server performance is a complicated thing and trying to limit it to one measure or one query can lead you down the wrong path.

Related Posts

Azure SQL Database and Extended Events

Dave Bland shows how to set up and read an extended event file on Azure SQL Database: This first step when using T-SQL to read Extended Files that are stored in an Azure Storage Account is to create a database credential.  Of course the credential will provide essential security information to connect to the Azure […]

Read More

Persisting SQL Server Databases on Kubernetes

Anthony Nocentino walks us through persistent volumes and Kubernetes: One of the key principals of Kubernetes is the ephemerality of Pods. No Pod is every redeployed, a completely new Pod is created. If a Pod dies, for whatever reason, a new Pod is created in its place there is no continuity in the state of […]

Read More

Categories

March 2019
MTWTFSS
« Feb Apr »
 123
45678910
11121314151617
18192021222324
25262728293031