Solutions > AppInsight Applications > Understanding AppInsight for SQL > Transaction Log Disk I/O

Transaction Log Disk I/O

This resource lists the current status of the transaction log file. The icons of the Volume column changes to reflect the listed volume's current state. Clicking the volume takes you to the Volume Details page.

  • File Path: Displays the full path where the transaction log file resides.
  • Volume: Displays the volume where the transaction log file resides. Clicking on the volume name takes you to the Volume Details View.
  • Disk Queue Length: Displays the current disk queue length for the listed volume as seen on the Volume Details view. Queue lengths that are high for a sustained period of time are indicative of disk I/O performance issues that can negatively impact the database.
  • Total IOPS: Displays the current total read and write IO operations occurring on the drive where the database or transaction log file resides. High I/O may be normal for some databases, but excessively high I/O leads to higher queue lengths, meaning there are more requests for disk reads or writes than the storage subsystem can handle.
  • Latency: Displays a measurement of disk latency occurring on the disk where the database or transaction log file resides. High volume latency values indicate sluggish database performance.

The performance counter, Database Files, is used to provide metrics for this resource. It is used in combination with volume polling. This counter is not listed in the resource; however, the thresholds can be changed.

Change thresholds for the Database Files performance counter

  1. From the Database Details view, locate the Database Files resource and click Edit in the Management field.
  2. Locate the Database Files performance counter and click [+] to expand the counter and reveal the counter details.
  3. Click Override Template and adjust the thresholds to suit your needs.
  4. When done, click Submit.