Question: What is a leap second and how will it impact my DB2 servers ? I have a bunch of DB2 servers hosted on Red Hat Linux 6.
Answer: It’s important to understand the definition of a leap second . I’m quoting from Wikipedia
“A leap second is a one-second adjustment that is occasionally applied to Coordinated Universal Time (UTC) in order to keep its time of day close to the mean solar time, or UT1. Without such a correction, time reckoned by Earth's rotation drifts away from atomic time because of irregularities in the Earth's rate of rotation. Since this system of correction was implemented in 1972, 25 such leap seconds have been inserted. The most recent one happened on June 30, 2012 at 23:59:60 UTC. A leap second, the 26th, will again be inserted at the end of June 30, 2015 at 23:59:60 UTC.”
According to IBM - Leap seconds are fully supported by DB2 on systems which use the UTC timescale.
DB2 utilises the Linux OS timsecales. The Linux OS timescales by default are typically based on UTC. Although you should double check the OS is not utilising TAI (International Atomic Time). TAI which is not supported by DB2.
On 30 June, 2012 there was a leap second. There were some reported cases of high Linux CPU on certain products .
Some Useful Links about Leap Second and the impact on other software
A documented example related to WebSphere MQ queue manager.
Read More on Measuring Linux CPU and OS