What are the availability of your system?

When I read the SQL Server resource kit today, I mentioned the availability of the system (Availablity)

I found that many of my previous understandings are still incorrect.

1. 99.9 is easily guaranteed?

It is hard to guarantee. 99.9, that is. Only 8.8 hours of offline time is required in a year, which means less than a month. So 99.X is still a goal.

2. 99.999 is just an ideal target. It requires only 5 minutes of offline time in a year, so it sounds like it is .;)

Therefore, to ensure these goals, concurrent maintenance, diagnosis, and disaster recovery are indispensable.

Calculation formula:

% Uptime/year = (8760-number of total hours down per year)/8760

% Uptime/month = (24 * number of days in the month)-number of total hours down in that calendar month)/(24 * number of days in the month)

% Uptime/week = (168-number of total hours down in that week)/168