Recovering from media failure

If your database is unusable, you have experienced a database failure. SQL Anywhere provides protection against the following types of failure:

Type of failure	Description	Examples
Media	The database file and/or the transaction log become unusable. This type of failure can occur because the file system or the device storing the database file becomes unusable, or because of file corruption. Backups protect your data against media failure.	The disk drive storing the database file or the transaction log file becomes unusable. The database file or the transaction log file becomes corrupt. This can happen because of hardware or software problems.
System	A system failure occurs when the computer or operating system fails while there are partially completed transactions. This type of failure can occur when the computer is inappropriately turned off or restarted, when another application causes the operating system to fail, or because of a power failure. After a system failure occurs, the database server recovers automatically when you next start the database. The results of each transaction committed before the system error are intact. All changes by transactions that were not committed before the system failure are canceled.	The computer or operating system becomes temporarily unavailable while there are partially completed transactions, perhaps because of a power failure or operating system failure, or because the computer is inappropriately restarted.

Type of failure

Description

Examples

Media

The database file and/or the transaction log become unusable. This type of failure can occur because the file system or the device storing the database file becomes unusable, or because of file corruption. Backups protect your data against media failure.

The disk drive storing the database file or the transaction log file becomes unusable.
The database file or the transaction log file becomes corrupt. This can happen because of hardware or software problems.

System

A system failure occurs when the computer or operating system fails while there are partially completed transactions. This type of failure can occur when the computer is inappropriately turned off or restarted, when another application causes the operating system to fail, or because of a power failure.

After a system failure occurs, the database server recovers automatically when you next start the database. The results of each transaction committed before the system error are intact. All changes by transactions that were not committed before the system failure are canceled.

The computer or operating system becomes temporarily unavailable while there are partially completed transactions, perhaps because of a power failure or operating system failure, or because the computer is inappropriately restarted.

Recover from media failure on the data
Recover from media failure on a transaction log mirror
Recover from media failure on an unmirrored transaction log

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