[mythtv-commits] Ticket #6838: OSX Frontend uses different timezone database then linux backend

[MythTV]

#6838: OSX Frontend uses different timezone database then linux backend
-------------------------+--------------------------------------------------
 Reporter:  kormoc       |        Owner:  mdean  
     Type:  defect       |       Status:  closed 
 Priority:  minor        |    Milestone:  unknown
Component:  Ports - OSX  |      Version:  head   
 Severity:  medium       |   Resolution:  invalid
  Mlocked:  0            |  
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Changes (by mdean):

  * status:  new => closed
  * resolution:  => invalid


Comment:

 #5872 (which I'll be applying in a couple of days) would allow you to use
 differently-named, but identical time zones on different hosts.  However,
 PST8PDT and US/Pacific are actually different time zones--in spite of the
 fact that the current time in both zones is identical, they have differed
 in the past.

 AIUI, PST8PDT is a simplified (and non-existent or "virtual") zone that
 will always pretend that Daylight Saving Time (DST) changes have always
 occurred in the past according to whatever happens to be the current rules
 in place for the US/Pacific (and, also, America/Los_Angeles) time zone.
 On the other hand, the US/Pacific (and America/Los_Angeles) time zone
 actually identifies exactly when DST changes really occurred each year
 since 1970.

 Therefore, any recordings (and their program information) made during the
 times when the zones disagree on the application of DST could not be
 shared by MythTV processes running with those differing zones.  And, since
 the start and end of DST in the US was changed in 2007, these particular
 zones could cause problems for recordings made as recently as 2006.

 You can check whether time zones are identical by comparing their zoneinfo
 files:
 {{{
 $ sha1sum /usr/share/zoneinfo/{PST8PDT,US/Pacific,America/Los_Angeles}
 e8f5742d0106cfe37cdc7077f06e6096674ec968 /usr/share/zoneinfo/PST8PDT
 672f38f4c16cb8d49777de607deaf270d73ade0c /usr/share/zoneinfo/US/Pacific
 672f38f4c16cb8d49777de607deaf270d73ade0c
 /usr/share/zoneinfo/America/Los_Angeles
 }}}
 If time zones actually differ (as, above, US/Pacific and
 America/Los_Angeles are identical but differ from PST8PDT), you will need
 to ensure that all MythTV processes (frontends/backends/mythtranscode/...)
 execute with the exact same time zone specified as the one used by your
 master backend.  You may change the time zone used by a process with:
 {{{
 export TZ='US/Pacific'
 }}}
 before executing the application.  However, since you must do this in each
 environment in which any MythTV application on the host will execute, it's
 generally easiest to simply change the system time zone on all hosts
 running MythTV applications to be identical.

-- 
Ticket URL: <http://svn.mythtv.org/trac/ticket/6838#comment:2>
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