SLA budget
Turn an uptime percentage into the downtime it actually buys you, per day, week, month and year.
That's your error budget — the time you may be down before the promise breaks. Assumes a 30-day month and 365-day year, the way SLA tables are written.
Three nines sounds thorough until you work out that it allows nearly nine hours of downtime a year, and about forty-three minutes a month. Four nines is fifty-two minutes a year. The difference between those two numbers is the difference between an on-call rotation you can staff and one you cannot, which is why it is worth seeing the figure before you agree to it.
Type a percentage and every window is worked out at once. It also runs backwards: if you know you were down for forty minutes last month, it tells you what availability that leaves you with, which is the version you need when someone asks whether the quarter's target survived.
What people open it for
- Checking what an SLA in a contract commits you to before signing it
- Working out whether last month's incident broke the quarterly target
- Comparing 99.9% against 99.95% in minutes rather than decimals
In the terminal
sla 99.95
Every utility is also a command in the desktop's shell.