4.8 "alternate system clock has died" error

[Charles Sprickman]

On Fri, 18 Nov 2005, Uwe Doering wrote:

> Charles Sprickman wrote:
>> Hello all,
>> 
>> I've been digging through Google for more information on this.  I have a 
>> 4.8 box that's been up for about 430 days.  In the last week or so, top and 
>> ps have started reporting all CPU usage numbers as zero, and running 
>> "systat -vmstat" results in the message "The alternate system clock has 
>> died! Reverting to ``pigs'' display".
>> 
>> I've found instances of this message in the archives for some 3.x users, 
>> some pre 4.8 users and some 5.3 users.
>> 
>> There were a number of suggestions including a patch if pre-4.8, sending 
>> init a HUP, and setting the following sysctl mib: "kern.timecounter.method: 
>> 1".
>> 
>> I'm already at 4.8-p24, so I did not look into patching anything, and 
>> HUP'ing init and setting the sysctl mib does not seem to have any effect.
>> 
>> I'm not quite ready to believe that some hardware has actually failed. 
>> Perhaps due to the long uptime something has rolled over?
>
> We had this once at work, quite a while ago.  The "alternate system clock" is 
> in fact the Real Time Clock (RTC) on the mainboard.  In our case we were 
> lucky in that it was just the quartz device that failed due to an improperly 
> soldered lead which finally came off.  We fixed the soldering and the problem 
> was gone.

Are there any tools to verify that the RTC is working?  I don't exactly 
understand what the RTC is, but would the machine not be suffering some 
other problems if there was an actual hardware failure?  Doesn't the 
system rely on this to time everything from the processors to memory to 
PCI slots and interrupts?

Is there any simple way to figure out if this is hardware or software?

> Now, there are of course plenty of other hardware reasons why the RTC can 
> fail, even temporarily like in your case.  Perhaps it is really time for a 
> new mainboard.

Ouch, that would hurt.  This machine does not have much room for tinkering 
(mail server).

Thanks,

Charles

>   Uwe
> -- 
> Uwe Doering         |  EscapeBox - Managed On-Demand UNIX Servers
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