Database Reference
In-Depth Information
intended to get you thinking about the many things you have to consider if you want to
successfully virtualize your SQL Server database. Let's talk about a few of the items in
this list in more detail.
Service-Level Agreements (SLAs), RPOs, and RTOs
Take the time to sit down with your stakeholders and understand what they need from
the database in terms of performance, recoverability, and uptime. Take the time to
understand what the business requirements are around recovery point objectives (RPOs)
and recovery time objectives (RTOs) concerning the database.
Table 4.1
is a useful chart you can use to translate the different levels of availability and
what they really mean in terms of database downtime for the year, month, or week.
Work with the stakeholders who rely on the database to determine just how long the
business can tolerate the database being down, and then map that back to an
infrastructure that is able to meet or exceed those requirements.
Table 4.1
Availability Chart
A common mistake people make during this process is not taking into consideration the
maximum tolerable database downtime for a single incident. What would be the impact
if all of your acceptable annual downtime occurred in a single event? As you can see in
Table 4.1
,
it is possible for the database to be down for three days in a row and still
have 99% availability
, but if that event happened at the wrong time of year, it could be
a disaster for the business.
Our experience has taught us that many times the ways organizations are doing things
today are based on the constraints that existed in the past. A virtualized infrastructure
offers you options that did not exist before, and by leveraging this technology, you
should be able to change the way you are currently doing things that will meet the
requirements of the business, improve overall availability of the infrastructure for the
database, and at the same time save money.
It also important that you set proper expectations with your stakeholders concerning
what service levels you can provide. If you have not had the conversation about
realistic service-level agreements that are achievable, then use this opportunity to sit
