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ASYNC_IO_COMPLETION

Short Description

Occurs when a task is waiting for I/Os to finish.

Detailed Description

Occurs when a task is waiting for asynchronous non-data I/Os to finish. Examples include I/O involved in warm standby log shipping, database mirroring, some bulk import related operations.

How to reduce this wait

The important thing with I/O waits is to be able to distinguish between the normal level of waits for your system and something that needs investigating. as you seeing this wait, along with PAGEIOLATCH_SH is completely normal for SQL databases.

  • Check current I/O volumes and response times against your baselines
  • If the volume of I/O requests has increased to the point where you are seeing a problem, then look to see what is happening in your application layer to drive the increased load.
  • If the response time has increased beyond acceptable then look to the server's disk subsystem for issues.

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