Writing

Feed Software, technology, sysadmin war stories, and more.

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.