A fast restore doesn??™t mean a need for five nines of
uptime; it means a need to return a database to functioning status as quickly as possible.
High-availability techniques are intended to keep a database functional continuously. It??™s
extremely important to differentiate between the need for fast recovery and the need for
high availability. They are not synonymous. Many a backup recovery plan design has
been muddled by confusing high availability and fast restore.
Requirements
The database should have as little perceived downtime as possible. Note that the key here
is perceived downtime, not actual, physical downtime. From an end-user (and executive)
perspective, it only matters that the database is unusable. Why it is unusable is irrelevant.
Save any discussion for the real source of the problem until after the issue is resolved.
You also must define and document the time period each day (or each week, etc.)
during which it is critical that the database be operational. As mentioned previously, this
scenario applies to more than 24x7 uptime requirements. Imagine a system that creates
CHAPTER 5 n CREATING A BACKUP/RECOVERY PLAN 128
shipping manifests for the morning load of delivery trucks.
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