Preparing Your Datacenters for DST Changes? 114
Cheeze asks: "As I am sure some of you know, Daylight Saving Time is slated to change this year thanks to The Energy Policy Act of 2005. This means nothing to the large majority of the population except they will either sleep late one day or have to commute in the dark. To a select few, this is a crunch time akin to the Y2K fiasco, only there has been almost zero publicity recently. These select few are the ones responsible for updating the millions of computers, both servers and workstations, with the new time zone information. For newer servers, this usually means just install a patch and reboot (which is slightly more than mildly inconvenient). For older servers, this is basically an 'End of Life' declaration. Servers running software for which no patch is available will be unable to update their own clocks. This doesn't seem like such a big deal until you realize Microsoft is only offering patches for Windows XP and beyond, and Sun will not be supporting Solaris 7 and older. That should knock a large percentage of the computers 1 hour off for a few weeks this spring. What are you doing in your datacenters to prepare?"
Are you saying.. (Score:2, Insightful)
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Point taken.
What are you doing in your datacenters to prepare? (Score:5, Informative)
Re:What are you doing in your datacenters to prepa (Score:5, Insightful)
OTOH, what kind of evil company won't even give as trivial a patch as updating a time-zone file to their customers!?! If I had any such software and the company still existed I'd be wanting a full refund.
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OTOH, what kind of evil company won't even give as trivial a patch as updating a time-zone file to their customers!?!
Only true for systems that were built using shared time-zone files to begin with. I know of at least one "UNIX Like" real-time OS that was built with the time-zone table as data in a library that was then statically linked into all of the executables that used it. It might have made some sense in a real-time and/or embedded OS to do it that way, but it means you need to rebuild and replace all of those executables. If you then factor in all of the versions of all of those, it becomes a monstrous task.
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come on, after all, it's just ONE (at most FOUR) bytes that will change with this in the whole executable.
You also have to look for what you applications do (Score:5, Insightful)
We have a web event calendar where people can schedule events (for far into the future). When people input an event, they specify the date/time it will begin/end. The application then converts the date/time into a unix timestamp and stores it in the database. Later, when an event is being viewed, the timestamp is converted back to a textual date/time.
The conversion from local time to timestamp is done via PHP functions, which uses the systems timezone file. The OS patch to fix this problem simply updates the timezone file and everything should automatically work.
This is fine and dandy for most things, but I ran into one small glitch. For any events that are scheduled between the new start of DST and the old start of DST (roughly a 3 week period), if they were created BEFORE the patch was applied, they are now off by 1 hour AFTER the patch is applied.
The 1 hour difference is simple enough, and I might not have even noticed...or if I had, I probably would have just blamed it on user error when entering the data. However, this caused a strange side effect. The application built a secondary index to simplify searching for events. The index consisted of the event_id and the starting timestamp truncated to midnight. Of course, for those events in that 3 week period that were created before the patch was applied, they now had an index timestamp that was actually 1 AM. Of course, this caused events to mysteriously disappear from the calendar. You could search for them, but not see them when browsing.
I wasted a good couple of hours on this problem (thinking at first that it was isolated to a single event) before I finally did an analysis of the entire index and discovered that almost all events in that 3 week period were wrong. Then it instantly dawned on me what had happened.
Re:You also have to look for what you applications (Score:1)
> This is fine and dandy for most things, but I ran into one small glitch. For any events that are scheduled between the new start of DST and the old start of DST (roughly a 3 week period), if they were created BEFORE the patch was applied, they are now off by 1 hour AFTER the patch is applied.
Perhaps if you had inputted your events on your program's terms by scheduling them one hour early -- since your program didn't know about the DST change, but you did -- then, after you apply the patch, your even
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This is fine well and good except - all UNIX systems (Linux, *BSD included) already work in UTC and convert to localtime on the fly.
Try the following on any UNIX system...
and you will see all three xclock windows with different times. The REAL problem of the Timezone change is that Noon of March 12th, 2007 is now an hour off from what we used to assume it would be.Europe (Score:2, Interesting)
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I believe that's the case with Lotus Notes. I am not a Sys Admin, so I don't know. But it would seem like most of this is handled at the OS level anyway. We have a couple days to patch yet, right?
After Y2K, I doubt most folks will lose sleep over this one. (That is if anyone is still in their same job.)
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[though these bugs may have been fixed by now.. since they're so stupid]
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Not this year (Score:2)
The good thing is that when we get around to doing it our US colleages will have found all the problems!
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and the only effect we might see is incorrect time zone in e.g. mail headers from the US, if sent from an unpatched mail server with the wrong time. Or am I forgetting something?
Yes, you are forgetting mail headers from Canada :)
Avoid the problem in the US (Score:5, Funny)
-ez
Re:Avoid the problem in Canada (Score:1)
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Neither can wheat, but at least it doesn't slime up the keyboard.
Sadly, even in SK, the computer would need patching, so that when the person moves to Alberta, their computer time can be correctly set automatically when they arrive. Meanwhile VCRs and other devices pre-programmed to switch to DST are just going to remain "broken" forever. Yet another monument to the Bush years in government -- all in the name of saving 1% of the State's oil a year, when they could be saving 40% easily by
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In any event, my iBook automatically observed the change, and it was nothing more than a matter of setting my desktop to New York time rather than Indianapolis.
Because there were already time zone definitions that Indiana was moving into, there wasn't a big de
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But not to the Navajo Nation, which covers northeastern Arizona and follows DST. But the Hopi reservation would be OK. (It's in Arizona, surrounded by the Navaho reservation, and does not follow DST.)
Dump DST! (Score:2)
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For those of us further north, DST is helpful, because having the sun rise at 4am and set at 8pm is wasteful, as most people don't start their days until much after 4, and their evenings certainly don't end at 8.
There was an interesting article [slate.com] in Slate a while ago arguing that it's not DST that should go, but time zones altogether.
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Obviously you're not a parent...
I'm more concerned of a switch back to the old.... (Score:4, Funny)
Re:I'm more concerned of a switch back to the old. (Score:2)
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Can't be done (Score:2)
You can never "unpatch" this. You can add an additional patch which would specify the new rules, which would coincide with the old rules.
The thing is, a change like this is always and forever. If at any point in the future, even after this law has been rolled back, you want to know about time during this period, your system will have to know what rules were in effect at the time.
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Maybe a few years pass with the new DST rules, then the government pulls a 180 and decides to go back to the old DST. What if Microsoft decides not to support some of the versions they allowed to be patched before? They may cover WinXP right now, but who says they will 3-5 years from now?
This goes for other operating systems. Will any business care to bother to provide patches to redo i
Servers should be on UTC anyway (Score:3, Informative)
Your client should convert the timezone. For a client machine, it's not much hassle just to go into clock settings and change it.
Worst case is web-apps - the server clock should be UTC, but you still need to convert the time zone in the client-facing PHP/Perl/Java/etc code. There you're just looking at a patch to the language runtime or whatever.
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Even on the web-apps I write, I always convert to GMT (or UTC, whichever terminology you care to use) rather than shafting about with time-changes, time-zone issues, and all that cack.
Mind you, I also rarely (if ever) use the timestamps as an identifier either, for similar reasons.
I suspect that if a server/db is using timestamps (including microtime, or whatever) as a unique identifier, then that's a whole new world of hurt.
Re:People should be on UTC anyway (Score:3, Interesting)
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I can't recall off the top of my head if time zone data are stored as text informa
Dammit (Score:5, Funny)
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I have helped to maintain some computers in my local Orthodox Christian church. Orthodox Church _still_ uses Julian calendar (that's why Orthodox Christmas is celebrated on Jan 7), so I had to install patches that add Orthodox calendar support to Windows. It was not funny.
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You think that was bad? You should have been around for the BC to AD conversion. Yikes.
BC to AD (Score:4, Funny)
We thought we were going to be fine with that here, as we had some wise men who worked out when they were going to start. We were planning on just using an integer for number of years:positive for AD, negative for BC. However, some idiot politician somewhere decided to start labelling the years at 1 instead of 0, so now we've got an out-by-one bug every time you try to do a calculation that crosses the AD/BC boundary.
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Where to get time zone info source files from (Score:4, Interesting)
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This also applies to all Mac OS X machines as well, of course. Apple will supply a new set of timezone files in a patch (if they haven't already), and there's absolutely no reason it won't be available for every version of OS X (since they should be the exact same files, the format hasn't changed). Doesn't Windows use a similar method? I thought pretty much everything had switched over to zic-based timezone files (which also takes care of all those pesky leap-seconds that everyone seemed to be so worried
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The Java 1.4.2_09 shipping with Mac OS X 10.4.x doesn't include the timezone changes, nor will it. Unless Apple ships a new Java 1.4.2, the only Java supporting the new timezone changes on Mac OS X is Java 5.
It also looks like WebObjects uses its own timezone files, and these haven't been updated in quite a while. Anyone doing any time/date manipulation in a WO a
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Apple really should release updated timezone files as an update for all versions, there's no reason not to. Failing that, it would be very easy for someone to provide an unofficial update to fix it, either by copying the files from 10.4 or just compiling them from the updated sources.
I'm surprised that Java doesn't just use the C library routines for that functionality on platforms where it is available, but I see that you're right, 1.4.2 does not do it correctly, 1.5 does (on OS X 10.4.8).
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The system clock (which isn't the same as the CMOS real-time clock) is set to UTC. Whenever an app requests the time, it is returned to the app in UTC. The app then calls a localtime() function to convert UTC to whatever the local time is, by refering to the appropriate timezone table. However, some apps will record time in log enteries using UTC (and do the conversion when the log is displayed), others will store time stam
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Like Linux and every major Unix [ath0.com], you mean?
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What's worse (at least for us) is that the JVM has its own daylight-savings-time rule handling
Not quite true... (Score:4, Interesting)
They are offering support for Windows 2000, free with the right volume license, $$$ without, or they have made a manual registry hack available (which I don't have handy because I'm posting from home).
And before you ask, there are companies that still specify Win2K server and workstation to run their software, Thompson/Prometric being one of them, which is how I came to find this out.
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HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones\Eastern Standard Time
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contr
Then just import it into a 2000 machine. Reboot and Ta Dah!
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You'd have to change it manually if the need arises.
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Patch to change DST? (Score:3, Informative)
A more complete description of the necessary registry changes is at
Microsoft Knowledgebase 914387 [microsoft.com].
But as someone already wrote in an earlier post: Set your servers to use NTP, either from your local nameservers or from *.pool.ntp.org and have it automatically adjust for DST.
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That would only affect the current time, which isn't much use if you are scheduling something to occur next month and the DST change occurs in between. The system needs to know about future (and past) DST changes in order to display all dates correctly. If you ever use a date (rather than just a time) you need more than just NTP synchronizing.
Overhyped (Score:2)
Uhh, no.
It's not inconvenient at all, unless you really think 2+ years of lead time isn't enough, and your systems really won't be rebooting even once in that entire period of time... Not likely.
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If you don't think it could be i
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Using Windows? You have to reboot once a month anyway, if your server faces the outside at all. Otherwise, you can just train your employees to use the time the server thinks it is. Ugly, but if you can't handle ten minutes of downtime on a server, that's the way to do it.
Of course, if you can't handle ten minutes of downtime, you have duplication. So why not patch the backup, test it
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I mean, come *on* - if you have an older-hardware system that "a reboot is too much of an outage', WTF
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I think with zic, patching java, and restarting the affected time-sensitive processes (syslog, cron, java), it should be possible to avoid rebooting.
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Then when you *do* need to reboot, you discover that some misapplied patch or config change from 2 years before was working as long as the the system kept running - but there was no possible way to get a clean correct startup.
Blegga.
(Another reason to have a spare system - that way you can *test* this stuff in a controlled fashion....)
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Never mind best practice would be to schedule a reboot on a regular basis, not because it's necessary but to guarantee servers will come up correctly given system changes, patches, etc.
Java... (Score:3, Interesting)
Our big issue is java... Whoever designed that piece of sh*t should be shot. They get the time information from the OS - so why not pull the TZ data from the OS too? But no - they rather implement it themselves... The result is beautiful. Oracle installed? You need an extra patch. Informix 10? Another patch. Websphere? Guess what - patch it separately! In the end, we had some boxes that needed 8 or more applications patched in addition to the OS.
Peter.
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Quick scan of some of our servers was showing between 5 & 10 Java.exe's, mostly in non standard locations. Some in user's home storage, some in our central binary shares. And *none* capable of handling the DST change.
The end result is that each server is going to have to be addressed *by hand* - no automated patching on this beast.
The bitch of it is that we're not only planning major work before March, but also next October - because there's a huge chance that
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either is a horrible choice.
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- Solaris/Windows/Linux: 1.4.2_11
- HP-UX: 1.4.2.11
- AIX: 1.4.2 SR 5 20060420
- Solaris/Windows/Linux: 1.5.0_06
- HP-UX: 5.0.3
- AIX: 5.0 SR 1 20060310
References:
HP: http://www.hp.com/products1/unix/java/DST-US.html [hp.com]
Solaris/Windows/Linux: http://java.sun.com/developer/technicalArticles/In tl/USDST/ [sun.com]
AIX : http://www-1.ibm.com/support/docview.wss?uid=swg21 232128 [ibm.com]
Clock Companies (Score:2, Interesting)
Time is an artificial construct (Score:1)
Each server and client has its own definition of time that has meaning to it. Seeking to establish hegemony over each definition is fascism at its worst. Every server and client can seek to be the same as others in of its own free will.
One day, at one time, all the clocks will be the same. At that moment, the Flying Spaghetti Monster will return in Glory. Ramen.
Until that day, time is nothing.
Incandescent vs CF bulbs (Score:1, Offtopic)
We should ban the numbers 13 and 911 too... (Score:3, Funny)
The impact on counting should be very minor, as I personally lived in an apartment on 12B for many years, and there was no cost to this. A few if statements here and there. Sure, there are some complications,
Look, for example at the daylight savings time, how simple it is to understand that on some days of the year, there are 23 hours, (where there is no 3:12 am.) and on others, there are 25 hours (where there are two 3:12 am's.) but only in some places, sometimes, depending on what the local government says.
It is great to change how people count... dollars, dimensions, hours, to serve political or societal goals. It makes life better for everyone. Much simpler than changing prices or opening hours to serve them. All we need to do is pass a law, and change the way we count. Simple and practical so that no one has to keep track.
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Thanks, asshole.. my birthday is on the 13th
Does this mean I'll be 28 forever?
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Well, there you see you are demonstrating the problem afflicting so many of our youth today.
If the proposal is accepted, no-one will have your problem in the future. While preventing problems
for future generations, we need to be sensitive to those who face challenges such as yours today. those who are most unfortunately afflicted with being born on the day between 12 and 14 could refer to their birth day as the '12B' of a month, and have the option of celebrating on either the 12th or 14th. In the modern
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the affirmative action directives.
Just set your TZ (Score:1)
std offset dst [offset],start[/time],end[/time]
Example: EST+5EDT,M4.1.0/2,M10.5.0/2
In the example EST is set to have the normal offset from UTC of 5 hours; since this is west of the prime meridian, the sign is positive. Summer time begins on the first Sunday in April at 2:00am, and ends on the la
Indiana had to deal with this already... (Score:1)
Not real fun change to have to deal with. Especially on the MS machines. I don't believe MS issued any patches for the change, just a post on how to change your timezone setting manually (which is all fine and good, except for applications that store the timezone with entries)
DIY Time Zone configuration (Score:3, Informative)
Under Unix, you could configure time zone changes yourself with zic.
For example, the following input to zic will create the four zone info files US/Eastern, US/Central, US/Mountain and US/Pacific. These will be under your ZONEINFO directory (mine is /usr/share/zoneinfo).
The input above configures the time change for the years 2007 to 2017 (an arbitrary end year) so that DST starts the second Sunday in March, and ends the first Sunday in November, as specified in the Energy Policy Act of 2005 [wikipedia.org].
You can test your resulting files using the zdump command, like this
You might have to refresh links to these new files, check /etc/localtime.
Disclaimer: I'm not a time zone expert, so don't take this on faith.
Bunch of whiners (Score:1)
The end result: people change it manually... And as they said, servers use UMT, so...
ZIC (Score:1)
Pretty much all UNIXes use text based TZ information, or tools that create
the correct information, (IE zic). Patches shouldn't be an issue. During the Y2K
fiasco^H^H^H^H^H^Hchanges all I did for my 150 odd servers is recompile my own
zoneinfo file and distribute via rsync.
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