If you ever see the following message in the Application Event Logs on your SQL Server database server:

SQL Server has encountered X occurrence(s) of I/O requests taking longer than 15 seconds to complete on file [Path to either your database's MDF or LDF files]

It can often mean that the Size/Shrink settings for the database files are not correct for the size of database. This articles suggestions some techniques for fixing this error message.

The following factors could be causing this error:

  • There is a physical issue on the drive that is hosting your database
  • The LDF/MDF file in question is too small and the Auto-Grow operating is taking too long, causing the entire operation to time out
  • The LDF/MDF file is highly fragmented.

We recommend the following steps:

  1. Check the hard drive that the MDF/LDF files are stored on and make sure that the drive is healthy and in the case of RAID arrays, make sure that there are no failures reported by the RAID controller.
  2. Size the MDF file to be at least 20% larger than the current size so that it has room to grow. Make sure that the MDF has an Auto-Grow size set to at least 20% of the current database MDF file size.
  3. Size the LDF to be at least 20% of the MDF and ideally pre-size it to be twice the largest size it has ever previously been. Also set the Auto-Grow to be at least 20% of its current size.
  4. Detach the database and perform a file-level defragmentation of the MDF and LDF files (e.g. use the SYSINTERNALS contig.exe application). Then reattach the database.


Article Info
  • Last Updated: 6/4/2014
  • Article ID: KB55
  • Views: 32747