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: Other
SQL Server versions: 2012, 2014, 2016, 2017


1 Answer


The backup background thread of the AlwaysOn primary database is waiting for a new work request from the secondary database. (typically, this occurs when the primary database is holding the BulkOp log and is waiting for the secondary database to indicate that the primary database can release the lock). Information from Microsoft®

Very rare

This wait never occurs for most instances

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

Prevalence of HADR_BACKUP_QUEUE across the Spotlight Population

For 86 % of hours with this wait, average wait time is less than 2 seconds

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

62 instances contributed data to this chart

Latency Distribution of HADR_BACKUP_QUEUE across the Spotlight Population