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Leap second causing Linux server crashes?

serverfault.com

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Re: Leap second causing Linux server crashes?

#61

Post by moe »

__david__ wrote: post #44

It appears to be fixed in Linux 3.4 [1]. According to the original commit [2] it's been broken since 7dffa3c673fbcf835cd7be80bb4aec8ad3f51168 [3], which appeared in 2.6.26. So, kernels between 2.6.26 and 3.3 (inclusive) are vulnerable. [1] https://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.... [2] https://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.... [3] https://git.kernel.org/?p=linux/kernel/git/t…

Which, in summary, is pretty much every production kernel out there.

Spent the last two hours recovering servers, tomorrow will be another interesting day.

Whoever figured it'd be a good idea to INSERT[1] the leap-second instead of just slowing/accelerating time...

[1] Clock: inserting leap second 23:59:60 UTC

Re: Leap second causing Linux server crashes?

#62

Post by [deleted] »

shaggy wrote: post #59

Pardon the ignorance if this is a stupid question. I've been looking at some of my hosts and have noticed a message "Clock: inserting leap second 23:59:60 UTC" in dmesg output but each of the hosts is in the EDT timezone so the I was under the impression that the leap second hadn't been applied yet. So what does that mean? That the systems have applied the leap second successfully or have only received it from their…

[deleted]

Re: Leap second causing Linux server crashes?

#63

Post by chimeracoder »

Aqwis wrote: post #56
spindritf wrote: post #47

Earlier quoted context omitted.

2012 and we still don't really know what time is. The fact that we can keep track of it, even with all the problems, is quite amazing.

Physics perfectly well knows what time is. This is an issue with keeping track of time in terms of seconds, minutes, hours and days, and has nothing to do with not knowing what time is.

What is time, other than a state in which net entropy within a closed system increases (which is already a definition abstract enough that it almost misses the point)?

Re: Leap second causing Linux server crashes?

#64

Post by ScottBurson »

infinite8s wrote: post #52
pud wrote: post #32

Earlier quoted context omitted.

A lot of engineers[1] spent a lot of time successfully fixing Y2K bugs. Because nothing well known blew up, many people wrongly assumed that Y2K was never a real problem to begin with. [1] I moved a Fortune 100 manufacturing company's database off an ancient mainframe that would've been disastrous come Y2K. It went smoothly and was thus a thankless job. They paid well though (mid six figures - those were the days).

When people say mid-six figures, do they mean 500k? Or 150k?

I think it means 300k -- 3 being a one-digit approximation to sqrt(10). I.e. the geometric mean of 100k and 1M.

Re: Leap second causing Linux server crashes?

#65

Post by DEinspanjer »

shaggy wrote: post #59

Pardon the ignorance if this is a stupid question. I've been looking at some of my hosts and have noticed a message "Clock: inserting leap second 23:59:60 UTC" in dmesg output but each of the hosts is in the EDT timezone so the I was under the impression that the leap second hadn't been applied yet. So what does that mean? That the systems have applied the leap second successfully or have only received it from their…

The leap second is applied at midnight UTC time, regardless of what timezone the server is in.

Re: Leap second causing Linux server crashes?

#68

Post by sayeed »

Our Linux instances running on Amazon EC2 had no issues since we are not running ntpd on these servers and adjtimex returns status as 64 (clock unsynchronized).

I think the Xen host takes care of the synchronization and we need not do it in the guest OS. (see http://serverfault.com/questions/100978/do-i-need-to-run-ntp...).

Is this fine or should we run ntpd for better accuracy?

Re: Leap second causing Linux server crashes?

#69

Post by shaggy »

DEinspanjer wrote: post #65
shaggy wrote: post #59

Pardon the ignorance if this is a stupid question. I've been looking at some of my hosts and have noticed a message "Clock: inserting leap second 23:59:60 UTC" in dmesg output but each of the hosts is in the EDT timezone so the I was under the impression that the leap second hadn't been applied yet. So what does that mean? That the systems have applied the leap second successfully or have only received it from their…

The leap second is applied at midnight UTC time, regardless of what timezone the server is in.

Okay, so does that mean that the various bugs that have been circulating can still hit as it hasn't hit midnight in EDT yet or can I exhale?

Re: Leap second causing Linux server crashes?

#70

Post by csarva »

sayeed wrote: post #68

Our Linux instances running on Amazon EC2 had no issues since we are not running ntpd on these servers and adjtimex returns status as 64 (clock unsynchronized). I think the Xen host takes care of the synchronization and we need not do it in the guest OS. (see http://serverfault.com/questions/100978/do-i-need-to-run-ntp... ). Is this fine or should we run ntpd for better accuracy?

Yes. This issue notwithstanding, you should be running ntpd.
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