Availability Guide for Problem Management

Planning for Disasters
Availability Guide for Problem Management–125509
8-11
Backup Site Alternatives
Online-Ready Sites
Online-ready sites (also referred to as processing-ready sites) are secondary computer
sites that are ready to take over processing from a primary site within an hour without
loss of data.
Table 8-1. Backup Site Alternatives: Advantages and Disadvantages (page 1 of 2)
Backup Site Advantages Disadvantages
Cold Site Inexpensive way to acquire
or lease a second computer
site.
No equipment or operating
costs until a disaster occurs.
Can require 20 days or more to
become operational. Everything from
furniture to computers must be
ordered, delivered, and installed.
Acquiring hardware during an
emergency might be difficult.
It is difficult to test a recovery plan
within defined time periods.
When leasing a cold site, there is a risk
of contention for use of the facility or
hardware in the event a widespread
disaster affects other companies under
contract for the same site. There are
restrictions on how long a tenant can
use the cold site.
Operational-Ready
Site
System and site are in a
ready state.
Security is in the control of
one company.
Simplifies recovery plan
testing.
If the system is large and is not part of
a network, ensuring database
consistency with the primary site
requires time and adversely affects the
primary system’s availability and
response time.
Data-Ready Site System and site are in a
ready state.
Security is in the control of
one company.
Simplifies recovery plan
testing.
Less expensive than an
online-ready site.
Data is only as current as the latest
backup. There is a risk of losing data
from transactions on the primary
system that have not been restored to
the data-ready systems.
Online-Ready Site Recovery occurs within an
hour, with no loss of data or
transactions.
Normal database backup can
be shared among nodes, thus
minimizing the burden on
any one system.
Simplifies recovery plan
testing.
Practical only for companies with
multiple computer sites.
More expensive than most of the other
alternatives.