Managing Database Backup and Recovery - High-Performance Web Databases: Design, Development, and Deployment - page 698

The application of each method will dictate the level of availability in the
system and the degree of time required in recovering from a failure. For ex-
ample, in a partitioned system the database is distributed between many
separate servers. Should one of the servers go down, only a portion of the
database becomes unavailable. Its cost is relatively high as there are many
servers deployed and it is set up in a modular fashion. Each server then
employs its own recovery mechanism.
In defining the level of protection needed to meet particular needs these
questions should be asked:
• Can the company run without the database for an extended period of
time?
• Are customer relationships risked if the database is unavailable?
• If the system becomes unavailable, is human life at risk?
If the answer is yes to any one of the above questions, some form of high
availability solution will be needed to meet the needs. As mentioned previ-
ously, a tape backup should form the foundation of any backup strategy.
Use the decision tree in Exhibit 4 to help guide the requirements for the
backup strategy.
Virus Protection
Although a database system is usually well protected against direct vi-
rus attacks, the database should be well secured from the rest of the com-
puting environment. This usually means protecting the database by
placing it on a dedicated system, making sure that the only way of reaching
the system is via administrative tools, the deployed middleware, or oper-
ating system-related administrative tools.
Even with a well-secured database, similar precautions will need to be
taken on the front-end systems, as well. Virus-checking utilities should be
deployed at the end user client workstations, and at any point in the envi-
ronment where data will be fed into the database. Of course, this depends
on the types of data being stored in the database. If binary large objects
(BLOBs) are allowed to be inserted into documents, applications, or imag-
es that a virus can attach to, it may be necessary to implement additional
levels of virus protection.
Internet and Intranet Firewalls
Database vendors are pursuing the ability to allow corporate data to be-
come extensible to the Web if it is not already there. Most databases pro-
vide for this by using extensions to the middleware or database interface,
providing extended data types in the database or providing plug-ins to the
database. This presents the problem of how to ensure that no one can gain
direct access to a corporate database. By implementing hardware/software