SQL Server has encountered 1 occurrence of I/O Requests taking longer than 15 seconds

  • I am seeing these messages in the sql server log file and I'm not sure what it means. I am not sure if this is a problem or not but it doesn't look right to see these types of messages in the log. See below.

    2009-07-28 23:00:37.91 spid2s SQL Server has encountered 1 occurrence(s) of I/O requests taking longer than 15 seconds to complete on file [H:\mssql\data\Archer\Archer.mdf] in database [Archer] (5). The OS file handle is 0x0000000000000808. The offset of the latest long I/O is: 0x00000001220000

    2009-07-28 23:11:47.88 spid2s SQL Server has encountered 2 occurrence(s) of I/O requests taking longer than 15 seconds to complete on file [H:\mssql\data\Archer\Archer.mdf] in database [Archer] (5). The OS file handle is 0x0000000000000808. The offset of the latest long I/O is: 0x00000002f90000

    2009-07-28 23:16:47.87 spid2s SQL Server has encountered 1 occurrence(s) of I/O requests taking longer than 15 seconds to complete on file [H:\mssql\txlog\Archer\Archer_log.ldf] in database [Archer] (5). The OS file handle is 0x000000000000080C. The offset of the latest long I/O is: 0x00000031a36200

    2009-07-28 23:16:47.87 spid2s SQL Server has encountered 1 occurrence(s) of I/O requests taking longer than 15 seconds to complete on file [H:\mssql\data\Archer\Archer.mdf] in database [Archer] (5). The OS file handle is 0x0000000000000808. The offset of the latest long I/O is: 0x00000003a00000

    2009-07-29 00:50:07.65 spid2s SQL Server has encountered 1 occurrence(s) of I/O requests taking longer than 15 seconds to complete on file [H:\mssql\data\MSSQL.1\MSSQL\DATA\templog.ldf] in database [tempdb] (2). The OS file handle is 0x00000000000006A8. The offset of the latest long I/O is: 0x0000000169a000

    2009-07-29 00:50:07.65 spid2s SQL Server has encountered 5 occurrence(s) of I/O requests taking longer than 15 seconds to complete on file [H:\mssql\txlog\Archer\Archer_log.ldf] in database [Archer] (5). The OS file handle is 0x000000000000080C. The offset of the latest long I/O is: 0x00000033399600

    2009-07-29 00:56:17.64 spid2s SQL Server has encountered 1 occurrence(s) of I/O requests taking longer than 15 seconds to complete on file [H:\mssql\txlog\Archer\Archer_log.ldf] in database [Archer] (5). The OS file handle is 0x000000000000080C. The offset of the latest long I/O is: 0x000000334b9a00

    2009-07-29 00:56:17.64 spid2s SQL Server has encountered 2 occurrence(s) of I/O requests taking longer than 15 second

  • It means pretty much what it says, SQL's detecting IO requests that take more than 15 seconds to complete. That is, the time between SQL issuing an IO request to the Operating system and the time that the IO actually competed was longer than 15 seconds.

    It's not good. It indicates that there's very slow performance of the IO subsystem. A single IO request should take milliseconds, not 15+ seconds. It's generally a sign that either your IO subsystem can't handle the load that's been requested of it, or there's unusually high IO activity.

    If you're getting these regularly, the first thing I'd suggest you do is separate the data and log files onto different physical drives.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass
  • Okay. Thank you Gail. I will be looking now on how to do that. I've never done it before so I will be investigating what the steps should be.

    Thanks again.

    Patti

  • Another thing that can cause this is insufficient memory, or improperly allocated memory. If the server is doing a lot of paging I/O it will impact performance, especially of your database file(s) are on the paging drive.

    Also, it may seem obvious but... if you have other processes running on your server can be consuming I/O and CPU bandwidth that will degrade SQL Server performance. Look at the profiler and/or task manager.

    The probability of survival is inversely proportional to the angle of arrival.

  • Did you figure out what your problem was? Mine just began to do this as well

  • I was facing the same issues on my development enviornment. I seperated the mdf & ldf files on different drives & this solved my issue.

    for reference you can read the below article by MICROSOFT

    http://blogs.msdn.com/chrissk/archive/2008/06/19/i-o-requests-taking-longer-than-15-seconds-to-complete-on-file.aspx

    Abhijit - http://abhijitmore.wordpress.com

  • Thanks, but I had setup my server up with that configuration when it was new.

  • Let me check with the Window's SA's. I believe there was something wrong with the SAN drives. There were also driver messages in the windows event log.

  • I remember some time back the same error occured repeatedly and we solved it by Moving the Datafiles of the multiple databases to a seperate drive fior each of them (Of course only Large DB's)

    You better try looking for the Drive and see what all Databases are using that drive and plan accordingly.


    Bru Medishetty

    Blog -- LearnSQLWithBru

    Join on Facebook Page Facebook.comLearnSQLWithBru

    Twitter -- BruMedishetty

  • For us, the SAN drive was shared by other servers that had databases on it. So it isn't as straight forward for us.

  • Thanks everyone. My data and log files are already on separate drives and no I don't have a SAN

  • Are you in a virtual environment? We had the same issues when our database server was a virtual server, when we switched it to a physical server all of our issues disappeared.

  • Nope, no virtual environment either, pretty standard setup

  • Any SQL / Windows jobs overlapping to each other or taking longer time than the usual. THsi could be the reason also.

    Abhijit - http://abhijitmore.wordpress.com

  • There are MANY things that can cause slow IO, although it is often a combination of them that lead to the 15 sec warning (that is REALLY bad, btw, as Gail pointed out). If you don't know much about performance analysis and tuning I HIGHLY recommend you get a professional to help you out. A few minutes/hours with a good tuner can make a HUGE difference. Or you can spend days or even weeks going back and forth on a forum trying to figure out the root cause(s). 🙂

    Best,
    Kevin G. Boles
    SQL Server Consultant
    SQL MVP 2007-2012
    TheSQLGuru on googles mail service

Viewing 15 posts - 1 through 15 (of 19 total)

You must be logged in to reply to this topic. Login to reply