Waitopedia is a comprehensive resource of information about SQL Server waits.

The description shown below is the top answer as voted by the Spotlight community.

The charts are based on 2.1 TB of data collected from 4207 instances uploaded by 323 Spotlight users over an 8 week period.


Category: IO
SQL Server versions: 2000, 2005, 2008, 2008 R2, 2012, 2014, 2016, 2017


2 Answers


Occurs while waiting for I/O operations to complete. This wait type generally represents non-data page I/Os. Data page I/O completion waits appear as PAGEIOLATCH_* waits. Information from Microsoft®


Used to indicate a wait for I/O for operation (typically synchronous) like sorts and various situations where the engine needs to do a synchronous I/O

Very common

This wait is very common for most instances

For each of 4207 instances, we ranked IO_COMPLETION on how frequent it is compared to all other recent waits. The chart shows the total of all rankings.

Prevalence of IO_COMPLETION across the Spotlight Population

For 42 % of hours with this wait, average wait time is less than 0.31 ms

For each instance, we found all the recent hours when it had a IO_COMPLETION wait. We found the average latency for each of those hours.

3615 instances contributed data to this chart

Latency Distribution of IO_COMPLETION across the Spotlight Population