Time Zone and Daylight Saving Time (DST) changes for Data ONTAP

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Abstract

Comprehensive information is provided about time zone and Daylight Saving Time (DST) changes which affect IBM® System Storage™ N series storage systems running any of the actively supported releases of the Data ONTAP® operating system. This document organizes current information about worldwide changes to time zone rules by country, and it includes a reference to general information and instructions for updating Data ONTAP to follow the time zone and DST rules.

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General Information

  • Time zone and Daylight Saving Time (DST) rules affect date and time processing functions in computers and applications. If not set properly, the time could be incorrect and adversely affect the operation of computers and the services they support. Since time zone and DST rules have been relatively stable in countries for many years, people have come to rely upon automated adjustments to time settings in association with their information technology.
  • Time and date calculations used with your system clock are based on time zone and DST rules that encompass other concepts such as "leap years" and "leap seconds" as described in the Frequently Asked Questions (FAQ) for Leap years & leap seconds topic found on the National Institute of Standards and Technology (NIST) web site.
  • DST changes should not be made by simply updating the system clock either manually or via an external time service. If the former DST rules are defined in your system, a simple change to the system clock will not change the DST rules that are used in time and date calculations.

Updates to Time Zone and Daylight Saving Time (DST) by Country
To support the following changes identified by country, updates have been made to accumulate these changes in the time zone files used by the Data ONTAP operating system for N series storage products. The time zone files provided by IBM are taken from the National Institute of Standards and Technology (NIST) repository.

    Armenia, Belarus, Ukraine, and Russia
    • In May 2011, the Russian government adopted a new law regarding their time zone rules. The effect of this law is that, on October 30, 2011, the clocks should stay at the same offset that they used in summer; that is UTC+4 for Moscow, the new Standard time that no longer uses DST. However, with previous versions of the zoneinfo package (2011J or earlier), all N series storage systems will fall back an hour in recognition of DST; therefore, it is necessary to update the zoneinfo package for Data ONTAP. Here are the offsets from UTC (Coordinated Universal Time) after the implementation of the updated time zone rules:
      1. Armenia: UTC+5
      2. Belarus: UTC+3
      3. Ukraine: UTC+3
      4. Russia: There are nine time zones in Russia, which currently observe times ranging from UTC+3 to UTC+12. Because of the cancelation of Daylight Saving Time, the offsets from UTC are altered. For example, the reference zone, Moscow Time Zone, now permanently uses UTC+4.

      To support this change, updates to the time zone files for N series storage systems were provided. Data ONTAP 8.1RC1 and later releases already include these updates.

      Please note that we are not aware of the Armenian government sending out an official request to correct an apparent inconsistency. IBM automatically sources all time zone information from an industry-wide authoritative source. If you are in Armenia and experience difficulties using the Armenian time zone, IBM suggests using UTC+5, or an equivalent time zone, until the authoritative version for Armenia is provided. Neither zoneinfo version 2011K nor version 2011L contain the corrections for Armenia that were included in the information to IBM.

    Australia
    • In March 2008, the Australian government extended their DST time for various locations. DST in Victoria, Tasmania, ACT, New South Wales and South Australia starts the first Sunday of October and ends the first Sunday in April the following year.
    • In 2006, Western Australia introduced DST for a three-year trial period starting December 2006. A referendum will be held in 2009 to decide whether DST should become permanent. Daylight saving starts at 2am Western Standard Time on the last Sunday in October, and ends at 2am Western Standard Time (3am summer time) on the last Sunday in March the following year.

    United States, Canada and Bermuda
    • In the United States, the Energy Policy Act of 2005 changed the rules for Daylight Saving Time (DST). These changes had their first effect in March 2007. Canada and Bermuda made similar changes to their DST rules to be consistent with the U.S. time changes. In order to support the new DST schedule, updates to the time zone files for N series storage products were provided.
    • Starting in 2007, DST for the United States, Canada and Bermuda was extended by four weeks; starting three weeks earlier on the second Sunday in March and ending one week later on the first Sunday in November.

    Venezuela
    • In December 2007, the Venezuelan government announced a change in the local time by 30 minutes. Starting at 03:00 a.m. on December 9, 2007, the time zone was changed from GMT-4 to GMT-4:30. To support this change, updates to the time zone files for N series storage products were provided.

Determining and Changing the Time Zone Setting for your N series Storage Systems
  • Prior to determining or changing the time zone setting of your storage system, update the storage system's time zone files, if required, as explained below.
    Each Data ONTAP release is shipped with a set of time zone files that were current when it was released. After a release of Data ONTAP has been made available, changes to time zone and DST rules by various governments require the time zone files to be updated separately for each storage system affected.

    The time zone files are compiled and placed in an archive (tar) file that is downloaded, extracted and installed on your storage system as explained in the Data ONTAP Time Zone Download/Installation Instructions.
  • To determine or change your storage system's time zone setting, use the timezone command as explained below. For a complete list of available time zone values that may be set, refer to the publications specific to the release of Data ONTAP installed on your storage system (i.e., select a Filer release to view the General Information section of the publication matrix, and read the "Data ONTAP Software Setup Guide").
    At the storage system's console, enter the following command to determine the current time zone in effect for your storage system:
      system_name> timezone

    You will see the following system messages when the command executes:
      Current time zone is location/ your_time_zone
    At the storage system's console, enter the following command to alter the time zone setting:
      system_name> timezone location / time_zone
      where:
        location / time_zone is the time zone setting selected.

      example settings:
      • America/Anchorage
      • America/Chicago
      • America/Denver
      • America/Edmonton
      • America/Los_Angeles
      • America/Montreal
      • America/New_York
      • America/Toronto
      • America/Vancouver
      • America/Winnipeg
      • Canada/Eastern
      • Canada/Central
      • Canada/Mountain
      • Canada/Pacific
      • US/Eastern
      • US/Central
      • US/Mountain
      • US/Pacific
      • EST5EDT
      • CST6CDT
      • MST7MDT
      • PST8PDT

    Note: The storage system does not need to be rebooted to set the time zone.

    Caution: Do not alter the time setting for the storage system forward and backward to attempt to verify the time zone's Daylight Saving Time (DST) rules. Doing so will cause the scheduled Snapshots to no longer work until the storage system is rebooted.

Exceptions to DST Rules
  • Although Daylight Saving changes are included in your Data ONTAP release, your N series storage system will not observe daylight saving if its time zone is set to any of the following values:
    1. EST
    2. MST
    3. HST
    4. America/Phoenix
    5. Pacific/Honolulu
    6. US/Arizona
    7. US/Hawaii

Cross reference information
Segment Product Component Platform Version Edition
Network Attached Storage (NAS) System Storage N3300 M/T 2859-A10- A20
Network Attached Storage (NAS) System Storage N3600 M/T 2862-A10- A20
Network Attached Storage (NAS) System Storage N3700 M/T 2863-A10- A20
Network Attached Storage (NAS) System Storage N5200 M/T 2864-A10- A20- G10- G20
Network Attached Storage (NAS) System Storage N5300 M/T 2869-A10- A20- G10- G20
Network Attached Storage (NAS) System Storage N5500 M/T 2865-A10- A20- G10- G20
Network Attached Storage (NAS) System Storage N5600 M/T 2868-A10- A20- G10- G20
Network Attached Storage (NAS) System Storage N6040 M/T 2858-A10- A20
Network Attached Storage (NAS) System Storage N6070 M/T 2858-A11- A21
Network Attached Storage (NAS) System Storage N7600 M/T 2866-A10- A20- G10- G20
Network Attached Storage (NAS) System Storage N7700 M/T 2866-A11- A21- G11- G21
Network Attached Storage (NAS) System Storage N7800 M/T 2867-A10- A20- G10- G20
Network Attached Storage (NAS) System Storage N7900 M/T 2867-A11- A21- G11- G21
Network Attached Storage (NAS) System Storage N6060 M/T 2858-A12- A22
Network Attached Storage (NAS) System Storage N3400 M/T 2859-A11- A21
Network Attached Storage (NAS) System Storage N6210 M/T 2858-C10- C20
Network Attached Storage (NAS) System Storage N6240 M/T 2858-E11- C21- E21
Network Attached Storage (NAS) System Storage N6270 M/T 2858-E12- C22- E22
Network Attached Storage (NAS) System Storage N7950T M/T 2867-E22
Network Attached Storage (NAS) System Storage N3220 M/T 2857-A12- A22
Network Attached Storage (NAS) System Storage N3240 M/T 2857-A14- A24
Network Attached Storage (NAS) System Storage N3150 M/T 2857-A15- A25
Network Attached Storage (NAS) System Storage N6220 M/T 2858-C15- C25- E15- E25
Network Attached Storage (NAS) System Storage N6250 M/T 2858-E16- E26
Network Attached Storage (NAS) System Storage N7550T M/T 2867-C20

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Document information


More support for:

Data ONTAP

Version:

Not Applicable

Operating system(s):

Data ONTAP

Reference #:

S1003463

Modified date:

2014-07-09

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