SQL Server Tips by Robin Schumacher

Object Resource Availability

In almost every database system, the DBA will find a hub table that passes critical data in and out. Such systems are not difficult to bring to a standstill. All it takes is a table being reorganized, an index becoming corrupt, or other such acts, and true database availability goes out the window. Many other factors can affect resource availability as well.

DBAs who have spent considerable time in their profession will, no doubt, have occasionally encountered a blocking lock tree that is a mile long usually consisting of one user blocking out everyone else, users waiting on memory structures to open up, or other contention events that affect overall efficiency. Total availability is heavily impacted by how available the critical resources used by the database are kept. It often affects the speed of the database as well.

Regardless of the database engine being used, the performance model needed will consist of an availability sub-model that is comprised of the aforementioned elements. For most critical businesses, availability is the first priority. Only after availability is confirmed can speed become the focus.

The above book excerpt is from:

High-Performance SQL Server DBA
Tuning & Optimization Secrets

ISBN: 0-9761573-6-5
Robin Schumacher

 http://www.rampant-books.com/book_2005_2_sql_server_dba.htm