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The designers of RMAN aimed at integration with Oracle database servers, [citation needed] providing block-level corruption detection during backup and restore processes. [ citation needed ] RMAN optimizes performance and space-consumption during backup with file multiplexing and backup-set compression; it integrates with Oracle Secure Backup ...
In database management systems, block contention (or data contention) refers to multiple processes or instances competing for access to the same index or data block at the same time. In general this can be caused by very frequent index or table scans, or frequent updates.
Data cleansing or data cleaning is the process of identifying and correcting (or removing) corrupt, inaccurate, or irrelevant records from a dataset, table, or database. It involves detecting incomplete, incorrect, or inaccurate parts of the data and then replacing, modifying, or deleting the affected data. [ 1 ]
Detected data corruption may be permanent with the loss of data, or may be temporary when some part of the system is able to detect and correct the error; there is no data corruption in the latter case. Data corruption can occur at any level in a system, from the host to the storage medium.
As a copy-on-write (CoW) file system for Linux, Btrfs provides fault isolation, corruption detection and correction, and file-system scrubbing. If the file system detects a checksum mismatch while reading a block, it first tries to obtain (or create) a good copy of this block from another device – if its internal mirroring or RAID techniques are in use.
Isolation is typically enforced at the database level. However, various client-side systems can also be used. It can be controlled in application frameworks or runtime containers such as J2EE Entity Beans [2] On older systems, it may be implemented systemically (by the application developers), for example through the use of temporary tables.
Data corruption and/or loss caused by the entry of invalid data or commands, mistakes in database or system administration processes, sabotage/criminal damage etc. Ross J. Anderson has often said that by their nature large databases will never be free of abuse by breaches of security; if a large system is designed for ease of access it becomes ...
For example, a computer file system may be configured on a fault-tolerant RAID array, but might not provide block-level checksums to detect and prevent silent data corruption. As another example, a database management system might be compliant with the ACID properties, but the RAID controller or hard disk drive's internal write cache might not be.