Linux Systems and the New DST 304
An anonymous reader writes "The recent changes in the Daylight Saving Time will affect virtually all computer systems in the US one week from now. Microsoft has been busy preparing Windows users for 'Y2DST,' and all the major Linux distributions have also issued patches. How can you be sure your Linux systems are ready, and what can you do to get them ready if they're not? This how-to article at Linux-Watch answers both questions in simple language and with easy-to-follow instructions."
Simple (Score:5, Interesting)
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Beware JVM Problems (Score:5, Informative)
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Not sure you'd see it in a home situation though.
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These are the java versions that natively include fixes for DST in 2007.
1.3.1_18+
1.4.2_11+
1.5.0_06+
So this means all 1.4.0 and 1.4.1 versions will not recognize DST unless you update them. Most vendors provided an update tool (tzupdater/jtzu) that can patch a variety of java versions. There is a table of available options for all vendors at: www
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You can set a Windows box to GMT...
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I mean, I want to have the internal clock / BIOS clock set to GMT, but the task bar clock set to whatever timezone I'm in.
Of course you can always change your clock to show GMT (In fact, that's what I do as I only uses Windows for games at home), but that doesn't count.
RealTimeIsUniversal (Score:2)
Search for RealTimeIsUniversal.
http://www.cl.cam.ac.uk/~mgk25/mswish/ut-rtc.html [cam.ac.uk]
Though, the registry setting is still not officially supported.
Re:Simple (Score:4, Interesting)
Tell that to my Outlook calendar. In two weeks when I host my telecon involving people from several states around the US, how many do you think are going to call on time, an hour early, or an hour late? I'm not looking forward to repeating myself over and over. Besides, 4k is chump change when you're talking about the time wasted when dozens of meetings get screwed up (mainly due to PEBKAC errors, but still.)
Windows-only "Y2DST" bugs (Score:4, Informative)
But if Outlook has "Y2DST" bugs, it stores or assumes that date/time is in local time, so events may be wrong if DST or the timezone of your server changes.
Note that these bugs if they exist could be reproduced otherwise by changing the timezone while programs are running. Events should happen at the same time, independent of timezone. (A real situation would be flying a live system/laptop to a new timezone).
But the bug in Windows is at a low level. Windows, for backward compatibility to DOS, assumes the hardware clock is local time. Any program that depends directly on the local time here, needs more than trivial algorithms to handle timezone and DST algorithms. These algorithms will fail, obviously if DST unexpectedly changes, and are probably in general not really expecting timezone to change. ( These algorithms could be compared with Y99-Y2K algorithms that tried to convert from a two digit year).
And obviously any programs that have such low level DST/Timezone handling code would fail if someone set the not often used RealTimeIsUniversal=1 in Windows.
In general no program should rely on local time, internally. Local time should only be used to convey information to the user. "You appointment is at XXX in your timezone", or "What time in your timezone would you like to schedule your meeting alarm?".
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I have a recurring meeting. It is at 11 AM Pacific Time every Tuesday, all year round.
Do I just set it up for 1900 UTC then? No, because when DST takes over, it will be off by one hour. Instead, I set it to 11 AM local time. MS Exchange performs the adjustment and schedules this meeting (and the conference room) for 1900 UTC for the winter months, shifting it to 1800 UTC when the software thinks DST takes effect. It doesn't calculate the times on the fly; it sets up the recurrences when
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Given that events (such as periodic meetings) are normally scheduled in local time, that's bogus.
In fact, having the calendaring tool store them in UTC breaks things even more. It means that the tool will convert them to UTC to store them and alarm them, then back to local time to display them. So when DST starts (even if at the EXPECTED time) a periodic meeting moves by an hour.
DST is an unmitigated disaster for programmers who w
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That's great, if you're going to be there. I have a MythTV box that records TV shows for me. I'm going to be out of town during the new change over, and if it didn't automatically update properly, I'd miss all of my shows after the time shift. If I tried to do it manually, I'd have to do it before I left, which would mean I'd miss my shows between when I left and DST, unless I set up a cron job to do it for me.
Fortunately, Ubuntu seems to be
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A very simple *nix test (Score:5, Informative)
$ date --date="Mar 25 15:00:00 UTC 2007"
If the output of both shows the same time (eg. 10:00 EST) then you've got a problem. If they show different times (eg. 10:00 EST and 11:00 EDT) then your system is ok.
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[~]:user@debian$ date --date="Mar 25 15:00:00 UTC 2006"
Sat Mar 25 09:00:00 CST 2006
[~]:user@debian$ date --date="Mar 25 15:00:00 UTC 2007"
Sun Mar 25 10:00:00 CDT 2007
Solaris Test (was Re:A very simple *nix test) (Score:3, Informative)
For Solaris you can still use zdump, just with a timezone entry instead of /etc/localtime:
zdump -v US/Eastern | grep 2007
From BigAdmin [sun.com]
I don't even have that many options. (Score:2)
date: illegal option -- -
date: illegal option -- d
date: invalid argument -- te=Mar 25 15:00:00 UTC 2007
usage: date [-u] mmddHHMM[[cc]yy][.SS]
date [-u] [+format]
date -a [-]sss[.fff]
Try this (Score:2)
date -d "Mar 25 15:00:00 UTC 2007"
Paste it to a gnome terminal.
Re:Looks like I'm screwed then (Score:5, Funny)
Win vs Lin (Score:5, Informative)
Re:Win vs Lin (Score:5, Funny)
Re:Win vs Lin (Score:5, Insightful)
Exactly. All the competent Windows admins have already switched to Linux.
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Especially if proper timestamping is a mission critical requirement, such as for real time systems, f
Re:Win vs Lin (Score:4, Insightful)
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It would be nice if you could dictate from end to end to use UTC but the real world doesn't always allow for it. And even if it did, you'd *still* need to verify your systems were DST comp
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The only problem MS made here is by not using UTC for Exchange calendar entries in the fi
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As an alternative, you could include timezone offsets with local time.
2007-03-06 07:30:00 -0800.
This is how email is stamped.
Then you are effectively passing both local time and UTC.
That way, the "subsystem" can effectually correct the bug and use effective UTC for calculations.
07:30 - (-08:00) = 15:30:00
BTW, I wish slashdot would display dates with timezone offsets.
But slashdot, has yet to fix use of Y99 dates.
( http
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That assumes a rather naive UTC/LocalTime conversion.
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No it assumes the *windows* conversion. Windows really does this.
Every time DST changes Windows reads the times of the files in explorer differently by one hour.
So you can't rely on timestamps in Windows. TBH the 'new DST' doesn't make any difference compared to what happens already. It's broken either way.
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Multiple timezone meetings (Score:4, Informative)
It's not possible to get a perfect solution to the problem. The best design I've seen stores times in UTC, together with a description of the entry timezone and the offset. Each user has a current local timezone (and it's assumed that users who travel will track these problems for themselves). When a change to DST comes along, the administrator can do some or all of the following:
The system also allows users to override the entry timezone on a per-entry basis. This means that I can enter a meeting in the UK marked as 9am Atlanta time, and be confident that it'll not only appear properly, but that if Atlanta's timezone changes on me, it'll be updated properly.
wrong (Score:2)
For display purposes, you display a time that's appropriate to the user's locale. If you're concerned about historical
data, you have your display be intelligent enough to know that the DST switch happened in 2007.
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The organizer of the meeting should, after the servers are patched and after their machine is patched, verify the calendar entries are in the right place, and fix them if not
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As much as I like linux, you are confusing two separate things: operating systems and applications. It is very easy to update windows to use the new DST rules. Frankly, even without patching, windows
My Windoz ME system (Score:2)
--
Real daylight savings: http://mdsolar.blogspot.com/2007/01/slashdot-user
NTP? (Score:4, Interesting)
Re:NTP? (Score:5, Informative)
However, if you're using an old zoneinfo file for local time, the interpretation of that UTC time is something else again, and NTP won't help you at all.
(Well, assuming you don't live in Arizona or Hawaii. Indiana's timing sucks, doesn't it?)
Re:NTP? (Score:5, Informative)
NTP as a protocol tracks the number of seconds elapsed since 1 January, 1900 UTC. It has absolutely zero knowledge of timezones or what they mean. Your NTP daemon of choise just sits there keeping your system clock reasonably accurate with UTC time and it's the relevant libc C time functions that read that UTC time, then read in the set zoneinfo data, and combine the two to give you and your apps local time.
It probably should (Score:2)
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The time zones "(GMT-8)Pacific; Tijuana" and "(GMT-8)Tijuana" are now different. (or will be in a week)
I wasted about 6 hours of testing, frustrated that the patches weren't working on a Windows test environment before noticing that I had teh wrong timezone. (And I'm only a short drive from Tijuana...)
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So I'm afraid your idea is a non starter.
Root Cause (Score:5, Insightful)
How many of you, after all, have told your State legislatures that this is stupid and it's time to opt out?
Re:Root Cause (Score:5, Insightful)
I like DST. I know how to set what clocks I have that still need to be changed. I enjoy the extra light at the end of the day. I am aware that I could just get up an hour early and try to convince everyone else that I have to deal with to do the same, but DST accomplishes that. Also, I live in a city that spans state lines, so having one state opt out would be a real hassle.
I would much rather lobby my legislature to allow wine to be shipped directly to my door. For crying out loud, I can get ammo delivered (and left on the doorstep) without even a signature, why can't I buy wine directly.
So, for all of those who dislike DST, try this: Just get up an hour later.
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I know you're just trying to be snarky, but that doesn't at all solve most people's problem with DST: the unneeded hassle, complication, and complete mess of having to deal with it. Even worse is when we make arbitrary changes to it, like this one.
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http://odur.let.rug.nl/~usa/B/bfranklin/franktxt.h tm [let.rug.nl]
That
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Absolutely. Never mind the fact that if we all shifted our schedules by an hour twice a year, then every single store sign displaying their hours would have to be changed twice a year, bus schedules would all have to be re-printed twice a year, hell ANYTHING with times on it would have to be changed twice a year. With DST we retain the same schedules, but you
Twelve is even better (Score:3)
That extra hour working late, waiting for the temperature to come down to the point where you can get into your car without risking second-degree burns?
That extra hour of hiding in your air-conditioned house waiting for the temperature to come down to the point where cooking dinner won't run up the bill for the whole month?
That extra hour of waiting for it to cool off enough that you can get some chores done without risking heatstroke?
And d
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On the bedtime issue, I definitely agree. I like it being light later, but bedtime is a HUGE chore for my kids during DST.
The increased energy costs during DST suck too. I'm in Indiana, so I was able to compare last year's (our first drinking the kool-aid) energy bills to prior years. My average monthly electric bill went up by about $5 over the same months in previous years. True, I'm only one data point and I can't comment on other people's energy bills, but my bills being higher is pretty important
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I usually get off work at 5pm. Sometimes 6ish. In the US, I have summer daylight till almost 10pm. I can cut my grass, swim a little, play some frisbee, and still cook burgers and dogs before dark.
In Japan, the first thing is that the sun comes up at like 4am. It's usually light by 3:30am and full sun my 4:30am. Sleeping in requires blackout devices on the windows.
Then, when you finally get home, you have, at best, 2 hours of light. Sun's down by 7pm and it's dark by 8
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Impeach Bush! (Score:2)
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Perhaps I can pressure my legislature to provide magic fairies who will change my clocks when the need arises.
The fact is, DST is not going away. Even if it disappears in some territories, it's safe to assume it will not disappear from all of them in our lifetimes. Thus, we're still going to have to deal with it on our computer systems. And so the constant calls of "abolish DST" remain entirely unhelpful.
Even better (Score:2)
Simple (Score:2)
Move to Antarctica.
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Move to Antarctica.
Though it might be more convenient to get to see him at the local Zoo.
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Better article (Score:3, Informative)
Let the circus begin (Score:2, Insightful)
My only regret was that I didn't milk that last consultant fee from a client before my router ran me over and stole my truck.
Shouldn't that be... (Score:2)
Or can we come up with an even more involved name?
Late in the game? (Score:2)
I've been watching people here at work going crazy as they realize that every router, switch, server, and voice switch in the network needs to be updated by next wee
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We're not all that concerned about network devices like firewalls, switches, etc. The only time sensitive data they have are logs, and si
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Forget patches. I wonder why anyone is still building systems that have DST hard-coded into them. DST definitions vary by country and can be changed by government ac
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Further, if your running Solaris it's not just a TZ patch. There's libc changes:
http://src.opensolaris.org/source/diff/onnv/onnv-g ate/usr/src/lib/libc/port/gen/localtime.c?r1=1138& r2=0 [opensolaris.org]
There's also glibc issues in RHEL
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Stupid saying... (Score:2)
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Springing backward seems to have a high risk for injury...
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How may we help you? (Score:5, Funny)
"Oh, Hi Manny, this is Stuart and I'm at our corporate IT HQ. We need help with the new DST configuration, please."
"Ok, Stuart, I'll be happy to provide whatever help I can, if you will just tell me the name of the corporation you're with, along with the contract ID and your callback number, you can hang up and I'll call you back so we can get things started."
"Ummm...Manny...excuse me, but I've never quite understood why you people always ask for the name of the corporation right off...what's up with that, if I may ask?"
"Well, Stuart, in our effort to provide the best quality service, we need to know upfront which company we are serving so we can insure that our responses fit with such things as non-disclosures, corporate culture, etc. As an example, since this incident deals with DST, if you are with Siemens, we're instructed to use twenty-four hour time, such as the time now being sixteen-forty-two hundred hours. If you are with Hertz Car Rental, the time is four forty-two pm."
"Oh, I see. Well, I'm with Microsoft, Manny, so what does the system say you should tell me?"
"Microsoft - I see. Well, Stuart, the big hand is on the four and the little hand is......."
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Tune in next time when Stuart calls Manny for help while attempting to program speed dialing on new corporate VIP mobile phones..
How to verify whether your system is up to date (Score:4, Informative)
A problem with DST in general (Score:3, Insightful)
Re:A problem with DST in general (Score:4, Informative)
For most of human history, time meant local solar time, or time by the moon and stars. It isn't until the mid 18th C. that the "longitude problem" is solved by the invention of precision marine chronometers. It isn't until the mid 19th C. that the "standard time" demanded by the telegraph, the railroad, trade and industry, intrudes on the lives of ordinary people.
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To see if you're patched... (Score:2)
$ zdump -v America/New_York | grep 2007
America/New_York Sun Mar 11 06:59:59 2007 UTC = Sun Mar 11 01:59:59 2007 EST isdst=0 gmtoff=-18000
America/New_York Sun Mar 11 07:00:00 2007 UTC = Sun Mar 11 03:00:00 2007 EDT isdst=1 gmtoff=-14400
America/New_York Sun Nov 4 05:59:59 2007 UTC = Sun Nov 4 01:59:59 2007 EDT isdst=1 gmtoff=-14400
America/New_York Sun Nov 4 06:00:00 2007 UTC = Sun Nov 4 01:00:00 2007 EST isdst=0 gmtoff=-18000
Substitute your timezone name as appropriat
Setting DST on older RedHat systems (Score:3, Informative)
The short answer... (Score:4, Informative)
cd
wget --passive-ftp ftp://elsie.nci.nih.gov/pub/tzdata2007c.tar.gz [nih.gov]
tar -xzvf tzdata2007c.tar.gz
zic northamerica
ln -sf
If you live outside the civilized world, insert the appropriate time zone in place of EST5EDT.
And finally, verify it with:
zdump -v
Which should say "Mar 11" and "Nov 4"
Just hire a few brazilians (Score:2, Interesting)
It's pretty funny all this fuss about DST changes. Here in Brazil we had to cope with DST changes almost every year for the last 20 years, and by now we pretty much got used to it, on our daily lives and when developing or maintaining computer systems. Every system administration knows that he'll have to update the tz database year, or update the Windows registry accordingly [microsoft.com].
I guess that's proof that in adversity, we thrive. Thanks to the screwed up economy we had a few decades ago, we know have one of th
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For Slackware 11 users... (Score:2)
Just thought I'd drop that tidbit of information if there is another Slackware user around here...
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In fact, my server is still running 10.2 and Patrick has released a patch for that version as well, and probably a few others.
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I should have guessed...
Yep, The Man is still on top of things.
Think of Canada, eh (Score:2)
So, if you're Canadian, or have boxes in Canadia, make sure the patch you applied will handle the Canadian timezone rules.
"zdump -v Canada/Eastern
I'm worried... (Score:4, Insightful)
I'm coming four hours early.
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Recent? It was two years ago... (Score:5, Insightful)
How to make sure your linux systems are ready: (Score:2)
Or a real-world example for gentoo, which takes approx. 15 minutes:
emerge --sync && emerge -u tzcode tzdata
Don't forget Java (Score:2)
The following link provides good information for patching Java from the 4 major java providers.
http://www.javasanity.org/article/3/dst-and-java-d ont-panic-it-can-be- [javasanity.org]
FreeBSD howto (Score:3, Informative)
1) Fetch the new rules file. I got it from:
http://www.freebsd.org/cgi/cvsweb.cgi/~checkout~/
2) Save it as
3) In
4) Run tzsetup - this copies the proper file from
5) Do a 'locate localtime' to see if you have any copies of
If you have multiple identical systems you can do this on one and then copy the new
I wonder (Score:3, Insightful)
FYI, Red Hat's Patch is Incorrect! (Score:3, Informative)
Just a head's up to anyone running Red Hat that their DST patch is incorrect. It's switching to Daylight Saving Time two hours earlier than it's supposed to.
CST6DST Sun Mar 11 05:59:59 2007 UTC = Sat Mar 10 23:59:59 2007 CST
isdst=0 gmtoff=-21600
CST6DST Sun Mar 11 06:00:00 2007 UTC = Sun Mar 11 01:00:00 2007 DST
isdst=1 gmtoff=-18000
CST6DST Sun Nov 4 04:59:59 2007 UTC = Sat Nov 3 23:59:59 2007 DST
isdst=1 gmtoff=-18000
CST6DST Sun Nov 4 05:00:00 2007 UTC = Sat Nov 3 23:00:00 2007 CST
isdst=0 gmtoff=-21600
Clock's are supposed to roll forward an hour at 1:59 A.M. not midnight.
We're having some fun with these patches. We've got about 400 machines to update (with three people) and are running about two dozen different releases of FreeBSD, OpenBSD, Red Hat Linux, Debian Linux, SCO, Solaris and Windows operating systems. And those are just the production servers; I can't wait until we do desktops.
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Consider waking up and having the radio tell you that we'll start doing DST on Sunday and our last "trial" was 15 years ago. I stayed unemployed for that one.
And as for Exchange, anything can make your IS refuse to restart, and updating it can require good luck and strong nerves.
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That's what I call relaxing.