More on Availability Statistics

Recall that I started a thread about obtaining Availability Statistics from Serio in my last post. I talked about identifying your Key Systems and thinking about the (Service Level Agreement) SLA you have with customers widely.

Recall also that if you want to access more of the theory there is a companion availability white paper available on our web site.

Having identified your Key Services, you need to think about what your Availability for the service should be. For example you might decide that your Billing System might need to be available Mon-Fri 9:00 to 17:00, excluding all public holidays. This is your 100% availability measure – if there is no downtime falling within these times, the Billing System is available 100%. You then need to create an SLA in Serio to represent this (I’ll call it an Availability SLA), and make a note of its name (it’s OK to re-use an existing SLA if one is to hand).

Tip: Make sure you are clear on what unavailability is. Sometimes it is obvious (flames coming from the back of the server) but there are other conditions where a given service is available but not performing correctly – maybe it is running very slowly. Think about what constitutes unavailability.

Having defined what your service times are, and with a strong understanding of what unavailability means you are ready to proceed.

You now need to think about how you are going to represent your Key Services in the Configuration Management Data Base (CMDB) – this is something you must have in order to obtain Availability statistics from Serio. There are two basic approaches you can take.

Represent Key Services as Items. In order words, create an Item that represents the service in the CMDB, or use a particular server already in the CMDB for unavailability Incidents (for instance, for your email service you might decide to use the email server itself).

Represent Key Services as Systems. This is my preferred approach – create a System that represents your Key Service (the System in Serio is a collection of Items that combine together in a structured way to deliver something of value to users).

Choose a method from those listed above, and apply it consistently. Then associate your Availability SLAs with the Items or Systems you are using for Availability purposes.

I’ll continue this thread with another post later in the week.