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Comment by choeger | Hacker News Reader

I have heard this anecdote before. In case you might not: 51days is awfully close to 2^32ms ...

The 51 days in the headline popped out to me because I have a Sonicwall brand firewall I help manage which requires a reboot every 51 days or it starts dropping packets. Yesterday was day 51 and like clockwork, it started failing.

Just for good measure: (2^32)/(1000 * 3600 * 24) = 49.71 days

so the correlation is meaningless here, as the reboot time is after the overflow.

It could very easily be that some manager decided to add an extra day to the schedule "just in case" as in close enough

2^32 * 1024us is 50.9 days.

This must be a coincidence because surely there is a large safety factor in this 51 day schedule. If the reboot is required to be every 51 days, surely the issue this is trying to avoid only appears after at least 3-4x as long.

> This AD requires repetitive cycling of the airplane electrical power. This AD was prompted by a report that the stale-data monitoring function of the common core system (CCS) may be lost when continuously powered on for 51 days

The issue appears after 51 days. I can't see in that AD a specific recommendation to reboot at predetermined intervals, just that it requires reboots before 51 days of continuous operation.

there was also a conjecture that the dreamliner required rebooting every 248 days due to a similar issue

https://www.engadget.com/2015-05-01-boeing-787-dreamliner-so...

2^32 * 1024us is 50.9 days. So it's probably a systick at 1.024ms overflowing a uint32_t.

tpmx (https://news.ycombinator.com/item?id=22761698) points out a related anecdote https://sites.google.com/site/edmarkovich2/whywindows95andwi... .

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