On 13 May 2021, at 16:19, Niall O'Reilly wrote:

I will share my arithmetic separately later.

So, as promised.

1. Time to recover five-nines availability after worst-case service-recovery delay:

   An hour’s outage must be matched by a minimum of 99,999 hours uninterrupted
   availability.

   99999 / ( 24 * 365 ) gives 11.4. That’s nearly eleven and a half years.

2. Maximum cumulative outage between RIPE meetings which would allow RIPE NCC
   to report achieving the five-nines target.

   RIPE meetings are held twice a year, but not precisely six months apart;
   the interval is approximately 180 days.

   Converting to seconds and dividing by 100,000 is equivalent to multiplying
   by 0.864, as there are 86400 seconds in a day.

   180 * 0.864 gives 155.5 seconds, or just over 2 minutes and 30 seconds.

Best regards,
Niall