With SLA monitoring configured, we can happily proceed with making sure our systems run smoothly; we do some maintenance during a properly scheduled maintenance period, only to discover that our SLA level has dropped. Were you sure downtime during maintenance periods wouldn't be counted against the SLA monitoring? Wrong. Zabbix host and host group-level maintenance doesn't affect SLA monitoring. If something is down during such a maintenance, Zabbix still considers that as an unacceptable unavailability of the service.

There's a way to avoid calculating SLA data for a specific period, though.

Let's go to Configuration | Services and click on Code repository. In the service properties, switch to the Time tab. Here, we can add three types of time periods:

• Uptime
• Downtime
• One-time downtime

Let's start with the simplest one—the One-time downtime. When adding a time period like that, we may enter a short description in the Note field, and we choose From-Till dates and times:

The note is not used for much, though—it's only displayed in the list of configured times, as shown in the preceding screenshot.

The Downtime option allows us to define times that will be excluded from the SLA calculation:

This is done on a weekly basis, where we may choose the weekday and time with minute precision. Unfortunately, here is the only place in Zabbix where a week sort of starts with Sunday. The biggest issue is that these periods can't cross the week border, hence it's actually impossible to add SLA calculation downtime for the weekend in one go—we would have to add one entry for Saturday and one for Sunday.

But what about the Uptime option? That one works in the reverse way. If an uptime entry is added, SLA calculation only happens during that time period; all other time is considered to be downtime.

Of course, when adding time periods here, we should obey the clauses from the actual agreement, not use this to hide problems from the SLA calculation, right?