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Friday, May 1, 2015

Another magic number to remember

Today's message is brought to you by the numbers 787 and 248.

This condition is caused by a software counter internal to the GCUs that will overflow after 248 days of continuous power.

See for yourself.

What's 248? Well, a 32 bit signed number rolls around 2.1 billion, with 86400 seconds in a day (usually!) and a 100 Hz counter...

$ echo '(2^31) / (86400 * 100)' | bc -l
248.55134814814814814814

There you go. Another one of life's magic numbers.

See also: "hey, 2147 looks familiar..." and this tale about atop, too.