DATABASE FAILURE

Database Failure

Database Failure

Introduction

When a database approach is used, a failure on the part of one user that damages the database can affect other users. Data base failure can cause different damages in different organization.

Discussion

Following are some examples of database failure. Many types of failures can befall your database. For example, a user may accidentally remove a file, or drop a table, or corrupt data, write Chris Zeis, Chris Ruel and Michael Wessler in Oracle 11g for Dummies. “Recovery Manager (or RMAN) is Oracle's backup and recovery solution to protect the files in your database.

Database failures (or the possibility of such) must be assumed to be lurking, ready to strike at some time in the future (Bergman, 2002). A prudent database administrator will plan for the inevitability of failures of all possible kinds, and will have appropriate plans and procedures in place before the failure occurs (Bergman, 2002).

Database recovery is necessary in the event of hardware or software failure. There are several categories of failures; some of these require relatively minor adjustments to the database, while others may depend on the existence of previously prepared database dumps and other recovery data sets (Ebeling, 2000). It should be emphasized that if your data is important and/or difficult to regenerate, then you should have considered and prepared for various failure scenarios.

Disk Filled

A filled data disk may result in subsequent corruption of database indexes, but not of the fundamental data tables. If the WAL files are on the same disk (as is the case for a default configuration) then a filled disk during database initialization may result in corrupted or incomplete WAL files (Jaffery, 2002). This failure condition is detected and the database will refuse to start up. You must free up additional space on the disk (or move the WAL area to another disk) and then restart the postmaster to recover from this condition.

csadmind Won't Start or Crashes During Startup

Since csadmind is the service that handles both the group scheduling engine (GSE) and the alarm dispatch engine, this could have been caused by offending entries in the GSE queue or the alarm queue.

When Communities or another IBM® Lotus® Connections feature experiences a database failure that involves restoring to a backup without replaying the transaction log to the point of failure, you can follow a number of steps to ensure a consistent data state for communities and their associated remote applications(Jaffery, 2002).

The Communities feature provides the option of adding extended functionality by adding widgets. Some of the available widgets are internal to the Communities feature, for example, the Members, Feeds, Bookmarks, and Forums widgets. Four of the widget types are applications that are external to Communities - these are the Activities, Blogs, Files, and Wiki widgets.

Communities is tightly integrated with the external widget data. However, when you perform backups of your databases, you might back up Communities database data on a different schedule than the other features' database data (Jones, 2007).

If a disaster occurs, for example, if the Activities database fails and you ...