Hi!
It appears that there have been some changes to tzdata recently. We run an application that needs the server to stay at GMT. Previously, we used the Casablanca timezone but now there seems to be a 1 hour difference to GMT. I checked the London zone and they seem to change time too.
I tried to change the zone to GMT with system-config-date (i'm using command line remotely) but didn't find the Greenwich zone! Is there any way to fixed this ?
[boig01@iode ~]$ date Tue Jun 3 14:10:21 WEST 2008 [boig01@iode ~]$ date -u Tue Jun 3 13:10:24 UTC 2008
Thanks in advance.
Guy Boisvert, ing. IngTegration inc.
P.S.: As i'm writing this, our application just started to desync !!! HOW CAN I ROLL BACK TZDATA ???? I Googled all over without finding any way to do it!
On Tue, Jun 3, 2008 at 10:36 AM, Guy Boisvert boisvert.guy@videotron.ca wrote:
Hi!
It appears that there have been some changes to tzdata recently. Werun an application that needs the server to stay at GMT. Previously, we used the Casablanca timezone but now there seems to be a 1 hour difference to GMT. I checked the London zone and they seem to change time too.
I tried to change the zone to GMT with system-config-date (i'm usingcommand line remotely) but didn't find the Greenwich zone! Is there any way to fixed this ?
cp /usr/share/zoneinfo/right/Etc/GMT-0 /etc/localtime
Guy Boisvert wrote:
Hi!
It appears that there have been some changes to tzdata recently. We run an application that needs the server to stay at GMT. Previously, we used the Casablanca timezone but now there seems to be a 1 hour difference to GMT. I checked the London zone and they seem to change time too.
Looks like you were never on GMT / UTC - but on British Time, Which in the summer is one hour off GMT
On Tuesday 03 June 2008 14:57:29 Karanbir Singh wrote:
Guy Boisvert wrote:
Hi!
It appears that there have been some changes to tzdata recently. We run an application that needs the server to stay at GMT. Previously, we used the Casablanca timezone but now there seems to be a 1 hour difference to GMT. I checked the London zone and they seem to change time too.
Looks like you were never on GMT / UTC - but on British Time, Which in the summer is one hour off GMT
Where/how is the system clock set? My server appears to have the system clock on GMT/UTC and KDE on British Time.
Anne
Anne Wilson wrote:
On Tuesday 03 June 2008 14:57:29 Karanbir Singh wrote:
Guy Boisvert wrote:
Hi!
It appears that there have been some changes to tzdata recently. We run an application that needs the server to stay at GMT. Previously, we used the Casablanca timezone but now there seems to be a 1 hour difference to GMT. I checked the London zone and they seem to change time too.
Looks like you were never on GMT / UTC - but on British Time, Which in the summer is one hour off GMT
Where/how is the system clock set? My server appears to have the system clock on GMT/UTC and KDE on British Time.
Anne
Hi!
Thanks for all the fast responses! I didn't know about the internals of the tzdata, the symlinks and the potential problems that Rick reported. So finally, before the 1st response arrived from the list, i decided to do a "brute force" downgrade.
I downloaded the previous CentOS tzdata file from:
http://rpm.pbone.net/index.php3/stat/3/srodzaj/1/search/tzdata
and did an rpm -ivh --force tzdata-2007k-2.el4.noarch.rpm
I rebooted the server and everything went ok! I didn't have the time to explain my case but for the sake of completeness, here it is:
1) Our application is for TV broadcasting. We have a complete in-house developped automatic broadcasting system.
2) We have two players (1 active, 1 standby) that run on Windows 2000 Server platform. There are 3 deamons: Copy service (from the big multi-terabyte library to local "cache" of 200 gigs), Broadcaster (playlist maker) and Player. The former 2 services read data from PostgreSQL database on CentOS x64 4.6. As is said, the Broadcaster service read from the database and make the playlist then send it to the player. Copier make check what it needs locally and act accrodingly. It managed a kind of big local cache.
3) The broadcast schedule is entered with a JAVA application that writes the time and date in GMT/UTC time in the database. The JAVA application knows the local time and the offset and write accordingly, adding the amount of time required (we are in Montreal so it's GMT-4 or GMT-5) to "reach" GMT+0.
4) The database servers have always been in Casablanca zone and until today, it seems that it was never changing time. 1st of june, tzdata was updated by a yum update and since then, it was only a question of time before we'de be offset. Playlists are looked up and made for 36 hours so today was panic day!
5) Stumbling across the problem, i read many strange things while Googling, related to what Rick said in his post to the list: localtime file, symlinks, etc. I was kinda lost!
Practically, as i said, i tried to find the GMT zone doing a system-config-date to no avail... I was shocked! We shouldn't be the only one to have this need!
So, as i decode from what i received in response to my initial post, and correct me if i'm wrong, all that does system-config-date is to copy a file from /usr/share/zoneinfo/... into /etc/localtime ? (and maybe set a couple of symlinks?).
And if i do what Marcelo said:
cp /usr/share/zoneinfo/right/Etc/GMT-0 /etc/localtime
am i cleared from future updates / changes in timezones? I simply want the server to stay at GMT+0 and never change timezone.
I'm waiting for advice from experts!
And would it be possible to include "GMT+0" in system-update-date ? What is strange on top of all that is that the time of the schedule seems to be stored on the database relative to the local time of the server... I'll have that checked by the programmers!
Many thanks to Marcelo, Rick, Karambir & Anne!
Guy Boisvert, ing. IngTegration inc.
Guy Boisvert wrote:
Anne Wilson wrote:
On Tuesday 03 June 2008 14:57:29 Karanbir Singh wrote:
Guy Boisvert wrote:
Hi!
It appears that there have been some changes to tzdata recently. We run an application that needs the server to stay at GMT. Previously, we used the Casablanca timezone but now there seems to be a 1 hour difference to GMT. I checked the London zone and they seem to change time too.
Looks like you were never on GMT / UTC - but on British Time, Which in the summer is one hour off GMT
Where/how is the system clock set? My server appears to have the system clock on GMT/UTC and KDE on British Time.
Anne
Hi!
Thanks for all the fast responses! I didn't know about theinternals of the tzdata, the symlinks and the potential problems that Rick reported. So finally, before the 1st response arrived from the list, i decided to do a "brute force" downgrade.
I downloaded the previous CentOS tzdata file from:
http://rpm.pbone.net/index.php3/stat/3/srodzaj/1/search/tzdata
and did an rpm -ivh --force tzdata-2007k-2.el4.noarch.rpm
I rebooted the server and everything went ok! I didn't have thetime to explain my case but for the sake of completeness, here it is:
- Our application is for TV broadcasting. We have a complete in-house
developped automatic broadcasting system.
- We have two players (1 active, 1 standby) that run on Windows 2000
Server platform. There are 3 deamons: Copy service (from the big multi-terabyte library to local "cache" of 200 gigs), Broadcaster (playlist maker) and Player. The former 2 services read data from PostgreSQL database on CentOS x64 4.6. As is said, the Broadcaster service read from the database and make the playlist then send it to the player. Copier make check what it needs locally and act accrodingly. It managed a kind of big local cache.
- The broadcast schedule is entered with a JAVA application that writes
the time and date in GMT/UTC time in the database. The JAVA application knows the local time and the offset and write accordingly, adding the amount of time required (we are in Montreal so it's GMT-4 or GMT-5) to "reach" GMT+0.
- The database servers have always been in Casablanca zone and until
today, it seems that it was never changing time. 1st of june, tzdata was updated by a yum update and since then, it was only a question of time before we'de be offset. Playlists are looked up and made for 36 hours so today was panic day!
- Stumbling across the problem, i read many strange things while
Googling, related to what Rick said in his post to the list: localtime file, symlinks, etc. I was kinda lost!
Practically, as i said, i tried to find the GMT zone doing a system-config-date to no avail... I was shocked! We shouldn't be the only one to have this need!
So, as i decode from what i received in response to my initial post, and correct me if i'm wrong, all that does system-config-date is to copy a file from /usr/share/zoneinfo/... into /etc/localtime ? (and maybe set a couple of symlinks?).
And if i do what Marcelo said:
cp /usr/share/zoneinfo/right/Etc/GMT-0 /etc/localtime
am i cleared from future updates / changes in timezones? I simply want the server to stay at GMT+0 and never change timezone.
I'm waiting for advice from experts!
And would it be possible to include "GMT+0" in system-update-date ? What is strange on top of all that is that the time of the schedule seems to be stored on the database relative to the local time of the server... I'll have that checked by the programmers!
I use UTC
make sure that the file /etc/sysconfig/clock says this: #---start cut ZONE="UTC" UTC=true ARC=false #---end cut
Copy the file /usr/share/zoneinfo/UTC to /etc/localtime
set the time via an ntp server with the command (if ntp is installed):
ntpdate -s 0.centos.pool.ntp.org
Then you should always be at the correct time.
NOTE: If you do not have the correct time zone in the /etc/sysconfig/clock file then on the next update, you will get the reset to the timezone that is there and not the one you manually copied in.
The UTC time zone is also available on install as a selection.
Thanks, Johnny Hughes
Johnny Hughes wrote:
I use UTC
make sure that the file /etc/sysconfig/clock says this: #---start cut ZONE="UTC" UTC=true ARC=false #---end cut
Copy the file /usr/share/zoneinfo/UTC to /etc/localtime
set the time via an ntp server with the command (if ntp is installed):
ntpdate -s 0.centos.pool.ntp.org
Then you should always be at the correct time.
NOTE: If you do not have the correct time zone in the /etc/sysconfig/clock file then on the next update, you will get the reset to the timezone that is there and not the one you manually copied in.
The UTC time zone is also available on install as a selection.
Thanks, Johnny Hughes
Thanks Johnny! Great info.
I edited the /etc/sysconfig/clock file and did what you said. I did also: cp -p /usr/share/zoneinfo/UTC /etc/localtime. I'll probably schedule a reboot, just to be sure all is clean. NTPd is already running.
Checking /usr/share/zoneinfo/, i saw GMT, GMT0, GMT-0, GMT+0, UTC & Greenwich. Does anybody knows the differences between all these or could provide a link to a reference? I found some infos but nothing that explains the subtlety.
I made a diff and they are binary different. I just want to understand better what happened to us and the "time" thing!
Regards,
Guy Boisvert, ing. IngTegration inc.
Checking /usr/share/zoneinfo/, i saw GMT, GMT0, GMT-0, GMT+0, UTC &Greenwich. Does anybody knows the differences between all these or could provide a link to a reference? I found some infos but nothing that explains the subtlety.
Basicly it comes down to GMT being based on the rotation of the earth around its axis and the sun (which isn't completely regular) and UTC being based on a Cesium atomic clock (which is far more accurate and regular). UTC is regularly modified with "leap seconds" so that it matches up to GMT to be the standard for date/time stamps. Also, UTC is the authoriative measurement for calculations involving duration.
plagarised from
http://people.etango.com/~markm/archives/2004/02/29/gmt_vs_utc.html
not sure about the GMT-0 GMT+0 or GMT0
mike
Anne Wilson wrote:
Where/how is the system clock set? My server appears to have the system clock on GMT/UTC and KDE on British Time.
you can use the 'hwclock' command to set / reset / retrieve the physical hardware clock timestamp. And you can use what Marcelo already pointed out to set a timezone if you like ( cp or ln -s a physical zone file from /usr/share/zoneinfo/ to /etc/localtime on the machine ).
Also, sanity check /etc/sysconfig/clock
On Tuesday 03 June 2008 17:06:09 Karanbir Singh wrote:
Anne Wilson wrote:
Where/how is the system clock set? My server appears to have the system clock on GMT/UTC and KDE on British Time.
you can use the 'hwclock' command to set / reset / retrieve the physical hardware clock timestamp. And you can use what Marcelo already pointed out to set a timezone if you like ( cp or ln -s a physical zone file from /usr/share/zoneinfo/ to /etc/localtime on the machine ).
Also, sanity check /etc/sysconfig/clock
Yes that did show up a difference, so I copied the GB file to localtime, rebooted to make absolutely sure that it wasn't working on the old setting, and hoped that the situation was cured. Unfortunately it isn't.
This is driving me crazy. Now I can make an appointment for 10a.m., and depending on which computer I use to read the korganizer file it may show up as 10a.m. or 11a.m., and there's no indication, of course, which computer originated the entry, so I can't tell which is the correct version.
Anne
Anne Wilson wrote:
This is driving me crazy. Now I can make an appointment for 10a.m., and depending on which computer I use to read the korganizer file it may show up as 10a.m. or 11a.m., and there's no indication, of course, which computer originated the entry, so I can't tell which is the correct version.
make sure the Hardware clock on all the machine is correct ( or setup and run ntpd ) and make sure that they are all on a valid timezone ( just typing 'date' on the command line should tell you ). If that still does not resolve the issue I'd guess your next action would be to post on the kde lists about this issue. Perhaps you have different versions of the same s/w on different machines - and they handle timezone adjustments differently ( as in, one version does, and another does not )
On Thursday 05 June 2008 11:14:16 Karanbir Singh wrote:
Anne Wilson wrote:
This is driving me crazy. Now I can make an appointment for 10a.m., and depending on which computer I use to read the korganizer file it may show up as 10a.m. or 11a.m., and there's no indication, of course, which computer originated the entry, so I can't tell which is the correct version.
make sure the Hardware clock on all the machine is correct ( or setup and run ntpd ) and make sure that they are all on a valid timezone ( just typing 'date' on the command line should tell you ). If that still does not resolve the issue I'd guess your next action would be to post on the kde lists about this issue. Perhaps you have different versions of the same s/w on different machines - and they handle timezone adjustments differently ( as in, one version does, and another does not )
I still can't find the difference between the boxes. KDE - it's possible. I've tried to ask a couple of times, but haven't managed to get the message clear enough to get an answer. The whole thing is extremely confusing. If I solve it I'll post the resolution, for the sake of the archives.
Anne
-
Anne Wilson -
Guy Boisvert -
Johnny Hughes -
Karanbir Singh -
Marcelo Roccasalva -
Michael Simpson