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IO_COMPLETION

Short Description

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.

Detailed Description​

This is a general wait state for synchronous I/Os related to:

  • reading transaction logs
  • reading and writing sort data during a sort spill
  • reading allocation bitmaps for start-up/restore actions

How to reduce this wait​

As with general I/O performance issues look for:

  • changes in execution plans
  • client side software releases
  • stuck processes

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