March 15, 2015 at 3:50 am
HI All,
We are seeing a strange issue, On my production server, after the backup job get competes using comvault tool, SQL service crash and restart. I see IO warning on the error log.
2015-03-12 02:00:25.59 spid7s SQL Server has encountered 24 occurrence(s) of I/O requests taking longer than 15 seconds to complete on file [i:\SQLDATA\Radio_FG1.mdf] in database [RadioWEB_DB] (5). The OS file handle is 0x0000000000000DD0. The offset of the latest long I/O is: 0x000013ec6f0000.
SQL service has been started 3 - 4 times in this month. This is a 24 logical processor box with 2 socket , 8 cores with 16 logical cores per socket with no NUMA configuration and running on Balanced power plan. SQL Server memory is 15 GB.
I am assuming may be due to uneven distribution of IO and memory SQL server is not able to handle IO and get restarted.
Could you please add your input to guide me . As this is a production box I have to identify the cause.
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March 15, 2015 at 8:31 am
Hi expert ,
Could you please provide your expert opinion.
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March 16, 2015 at 8:03 am
Please post up your SQL Server log where you see the restart. I highly doubt that a COMMVAULT DB backup is causing SQL Server to restart.
You I/Os taking longer than 15 seconds to complete means that something in the path to or your back end storage is extremely slow. These should be taking less than 15 milliseconds, not 15 seconds each. You need to get your SAN team involved on that issue.
Is there a pattern to when SQL Server restarts? Day of the week.. time of day... does it only restart at the end of a COMMVAULT backup, or just once in a while at the end of a COMMVAULT backup?
March 17, 2015 at 11:26 am
Balanced Power Plan? You want a production server to be using the "High Performance" plan to keep your cpu clocks at the maximum rated speed. At low times your clock speeds will slow down. High Performance will fix this issue.
Download and run the "CPUZ" utility and check to see if you can see your CPU clock speed slowing down with the balanced power plan...
March 17, 2015 at 11:34 am
When I experienced the issue I was already on the perforamance power plan....
March 17, 2015 at 11:42 am
Sorry I'm not saying that was the issue just good practice.
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