The 2015 Leap Second: What You Should Know

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Keeping time is a tricky business — especially when we’re talking about keeping time at a high precision level.

Every so often our clocks, which tend to follow Coordinated Universal Time, get a little out of sync with the Mean Solar Time.  When this happens, we Earthlings utilize a rather ingenious concept we call a “Leap Second”.  The idea is pretty similar to a “Leap Year”… except that it’s only a 1 second adjustment instead of an entire day.

That 1 second adjustment may not seem like much but, for some functions, high performance timekeeping is absolutely critical (such as for scientific and economic computing needs).

And, as it so happens, on June 30th of this year (2015) — at midnight — one additional Leap Second will be added.

Luckily, if you’re running SUSE Linux Enterprise, you are in good shape. Here’s a quick run-down of the high level information.  (For more detailed notes, see the Knowledge Base article.)

  • Running SUSE Linux Enterprise 12?  You’re all set — nothing you need to do here.
  • Same goes for SUSE Linux Enterprise 10 or earlier.
  • Currently on SUSE Linux Enterprise 11? You’ll want to make sure you’re properly updated to the latest kernel updates in order to make sure you are not impacted. Specifically:
    • SLE 11 SP1 – Kernel 2.6.32.59­0.7 or later.
    • SLE 11 SP2 – Kernel 3.0.38­0.5 or later.
    • SLE 11 SP3 – Not impacted, except for one known issue that will be fixed in the next maintenance update for SP3.
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Comments

  • Marijn says:

    Excellent article… Got a question from a customer yesterday about the leap second and have forwarded this!

  • ecomsup says:

    As metioned above “◦SLE 11 SP3 – Not impacted”

    So my question is if my kernel version is 3.0.101-0.46-default, sill do i need to upgrade kernel version ? or is it fine with 3.0.101-0.46-default kernel.

    Thanks.

  • ecomsup says:

    what will safe kernel version for SELS 11 SP3 ?

    As you mentioned ◦SLE 11 SP3 – Not impacted. In my case kerenel verion is 3.0.101-0.46-default. So is it fine with this kernel version or do i need to upgrade to latest kernel to avoid leap second insertion problem ?

  • robsteiger says:

    Fine to know! could you also give us an info about SLE 11 with no SP, what Kernel is ok?

  • mapryan says:

    Are SLES11 (SP1|SP3) hosts running PTP rather than ntp going to be ok? Presumably the advice would be similar to a host running ntp but not in slew mode?

  • sclind says:

    For 11 SP2 do you mean “3.0.38-0.5.1″ (not ” 3.0.38­0.5″?

  • jmortenson says:

    The kernel version are incorrect for SLES 11 SP1 and SP2. Please see TID 7016150 for more updated information.
    https://www.suse.com/support/kb/doc.php?id=7016150

  • rashidM says:

    with regards to document 7016150, after the time window of 30th june, lets say, 1st July, do I remove the -x from NTPD_OPTIONS and restart the ntp service?

  • provibe says:

    Can I simply avoid any leap second issues by disabling NTP during the leap second and re-enabling it afterwards? My systems don’t require high time accuracy.

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