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SQL server database recovery can be successful when the problem
is correctly diagnosed. Quick or inadequate fixes can lead to costly
downtime and a jeopardized recovery.
 When
a Single failed drive in a RAID 5 server has occurred but the
server is still operating and serving data to the users, the failed
drive is usually replaced.
When the failed drive is just a symptom of a bigger problem that
was not properly diagnosed then you are dealing with serious server
downtime and a data recovery specialist should be called in.
RAID 5 Server Has Failed
A real serious data loss emergency happens when Multiple drives
or a controller has failed. The server then becomes inaccessible.
An operator may replace the failed components and reconfigure the
system providing you with the following situations
- A functioning server that is missing valuable data
- A completely non-functional server.
In this case a data recovery specialist must be consulted.
- They will make what is called a mirror image of the data on
each discrete media involved.
- They will then proceed to rebuild the data that can be transferred
to a functioning server.
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SQL, Oracle DB2, Database corruption
When the Server has crashed or has experienced O/S problems
tables can be dropped or you can have a corrupt database.
Severe data loss can happen during the re-initializing of
the database when the DBA tries to recover data.
Using the transaction logs to "roll back" the database
to a known well state should only be attempted if the following
terms apply.
- It should only be attempted on an alternative server using
a copy of the problem data
- The transaction logs should be examined and deemed good.
- It can be done if physical drive problems have been ruled
out.
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Server Upgrading
Problems installing new application software, operating systems
or new hardware can render your server inaccessible. Before upgrading,
data should always be backed up to an alternative server.
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