2. DESCRIPCIÓN DEL PROBLEMA
3.5. EL APRENDIZAJE EXPERIENCIAL
This section contains brief definitions and/or explanations of some of the terms used and assumptions made when developing the data sheets found in this Oracle Backup Software Solution Buyer’s Guide.
CLI
A command-line interface (CLI) is a mechanism for inter- acting with a computer operating system or software by typing commands to perform specific tasks. This text-only interface contrasts with the use of a mouse pointer with a graphical user interface (GUI) to click on options, or menus on a text user interface to select options.
Compressed Backups
Compression reduces the amount of space needed by a backup. There are several ways of doing this. Some programs have support for compression built in. The gzip (-z) option for GNU tar pipes the whole backup through the gzip compression program before writing it to the backup medium. Unfortunately, compressed backups are problem- atic. Due to the nature of how compression works, if a single bit is wrong, all the rest of the compressed data will be unus- able. Some backup programs have some built in error correc- tion, but no method can handle a large number of errors. This means that if the backup is compressed the way GNU tar does it with the whole output compressed as a unit, a single error makes all the rest of the backup unusable.
Cross Platform Transportable Table space
When using RMAN, transporting table spaces between databases where the endian format is different between source and destination platforms, the endian format of the data files must be converted to match the destination plat- form. This conversion can be performed in two ways: Using the “RMAN CONVERT TABLESPACE” command (convert- ing on the source host) or using the “RMAN CONVERT DATAFILE” command (converting on the destination host).
Cumulative Incremental Backup
The backup software creates copies of all the files, or parts of files that have changed since previous backups of any type (full, differential or incremental) with each backup building on the previous backup. To restore the data, you will need the the last full backup and all the backups since that full backup.
DCIG 2011 ORACLE BACKUP SOFTWARE SOLUTIONS BUYER’S GUIDE
The Insider’s Guide to Evaluating Oracle Backup Software SolutionsAppendix A—Definitions, Explanations and Terminology
Data Pump
The Oracle Data Pump provides two utilities: Data Pump Export and Data Pump Import. This product replaces the pre-Oracle 10g import and export utilities (imp and exp). Data Pump Export (expdp) and Data Pump Import (impdp) are server-based rather than client-based as is the case for the original export (exp) and import (imp).
DBMS_PIPE
The DBMS_PIPE package lets two or more sessions in the same instance communicate. Oracle pipes are similar in concept to the pipes used in UNIX, but Oracle pipes are not implemented using the operating system pipe mecha- nisms. Information sent through Oracle pipes is buffered in the system global area (SGA).
DBVERIFY
DBVERIFY is an external command-line utility that performs a physical data structure integrity check on an offline data- base. It can be used against backup files and online files (or pieces of files). DBVERIFY is primarily used to ensure that a backup database (or data file) is valid before it is restored or as a diagnostic aid when a data corruption problem is encountered.
Deduplication
Deduplication is a specialized data compression technique for eliminating coarse-grained redundant data to improve storage utilization. There are various kinds of deduplication. Source-based deduplication means that you first dedupli- cate data and then backup the deduplicated data. This is less taxing on the networking as less data is sent to the backup media. Using target-based deduplication, data is first backed up by sending all of the data over the network, and then deduplicating it at the backup target.
Differential Incremental Backup
The backup software looks at which files have changed since the last full backup and then creates copies of all the files that are different from the ones in the full backup. If more than one differential backup is done, it will copy all the files, or parts of files that have changed since the last full backup, even if you already have identical copies of those files in a previous differential backup. To restore all the data, only the last full backup and differential backups are needed.
Disk Image Backup
This is when a copy of the database is made to any type of storage device (tape, disk, or CD). All data is backed up includ- ing free blocks with no data which can make this method of backup very slow and result in a very large backup.
Duplexing Backup Sets
RMAN can write duplexed backup sets that create up to four identical copies of each backup piece in a backup set to different destinations. Duplexing provides an extra layer of protection against disaster, media damage and human error. RMAN can duplex backup to either disk or tape but cannot duplex to disk and tape at the same time. Backup duplexing is not applicable to disk image backups.
Fast Recovery Area
Fast Recovery Area minimizes the need to manually manage disk space for backup-related files and balance the use of space among the different types of files. In this way, a fast recovery area simplifies the ongoing administration of your database.
Full Backup
A complete backup of an entire database.
Hot Backup
A Hot Backup is performed while software accessing that database is running. Traditional or cold backups require systems to be taken offline before backups are done.
Legacy Oracle Database Versions
These are older releases of Oracle databases that are no longer formally supported by Oracle under normal mainte- nance and support contracts.
Non-Archive Log Mode
Using Non-Archive Log Mode the archiving of the redo log is not enabled. In this mode, offline redo logs can (and will) be overwritten without first making sure they are saved. If the database fails you may lose everything since the last backup.
Oracle Clusterware
Oracle Clusterware is the cluster software required to run the Real Application Clusters (RAC) option for the Oracle database. It provides the basic clustering services that enable Oracle software to run in clustering mode.
DCIG 2011 ORACLE BACKUP SOFTWARE SOLUTIONS BUYER’S GUIDE
The Insider’s Guide to Evaluating Oracle Backup Software SolutionsAppendix A—Definitions, Explanations and Terminology
Oracle Data Guard
Oracle Data Guard supports both physical standby and logi- cal standby databases. It can be setup to facilitate failovers or switchovers to alternative hosts in the same or alterna- tive locations. The most common use of this feature is for Disaster Recovery Databases which are located off-site.
Oracle Flashback Technologies
Oracle Flashback Technologies are data recovery solutions that enable reversing errors by selectively and efficiently undoing the effects of a mistake. Before Flashback, an incorrect transaction that only took seconds to create could take hours to reverse. Using Flashback correcting an error takes about as long to reverse as it took to make it. In addition, the time required to recover from this error is not dependent on the database size. Flashback supports recovery at all levels including the row, transaction, and table levels, as well as the entire database.
Oracle GoldenGate
GoldenGate enables real-time data integration and continu- ous data availability by capturing and delivering updates to continuous data synchronization across heterogeneous envi- ronments. The most common application is to gain improved business intelligence across the enterprise by using more accurate and timely data and increased performance. Other uses include query offloading; zero-downtime upgrades and migrations; disaster recovery; and active-active databases for data distribution, data synchronization and high availability.
Oracle RAC
Oracle Real Applications Clusters (RAC) is a cluster data- base with a shared cache architecture that provides a highly scalable and available database solution. In an Oracle RAC environment, an instance has more than one identical data- base. This allows an application or user to connect to the instance and have access to a single set of data. If one of the RAC nodes fails, the other node seamlessly continues to operate without any loss of data or use of the system.
Oracle Secure Backup
Oracle Secure Backup provides centralized tape backup management for an integrated, easy-to-use solution that encrypts data to tape to safeguard against the misuse of sensitive data in the event that backup tapes are lost or stolen.
Oracle Streams
Oracle Streams helps propagate information within and between databases. It provides tools to capture, process (‘stage’) and manage database events via Advanced Queuing queues. Oracle Streams can be setup in homogeneous (all Oracle data- bases) or heterogeneous (non-Oracle and Oracle databases) environments. It uses database objects to share data and messages. Applications for the Oracle Streams toolset include data distribution, data warehousing and data replication.
Oracle Virtualization (VM)
Oracle VM is server virtualization software that fully supports both Oracle and non-Oracle applications and delivers more efficient performance. Oracle VM has the following features: server clustering and server virtualization technologies, integrated clustering, virtualization, storage, and management for grid computing.
Raw Partition Backup
This is related to disk imaging and is when a copy is made of the Database for backup purposes. All data is backed up including free blocks with no data which can result in backups that are both very slow and very large.
RMAN
Oracle Recovery Manager (RMAN) is a tool that allows for efficiently backing up and recovering an Oracle database. RMAN is designed to provide block-level corruption detection during backup and restore. RMAN optimizes performance and space consumption during backup with file multiplexing and backup-set compression, and integrates with Oracle Secure Backup and third-party media-management products for tape backup. RMAN provides a common interface for backup tasks across different host operating-systems, parallelization of backup/recovery data streams, backup-files retention policy, and detailed history of all backups.
RMAN Data Recovery Advisor
RMAN Data Recovery Advisor automates the diagnosis of database failures and corruptions, advises the recovery steps and performs automatic recoveries of the database failure.
RMAN Recovery Catalog
An RMAN Recovery Catalog is a schema stored in a database that tracks backups and stores scripts for use in RMAN backup and recovery situations.
DCIG 2011 ORACLE BACKUP SOFTWARE SOLUTIONS BUYER’S GUIDE
The Insider’s Guide to Evaluating Oracle Backup Software SolutionsAppendix A—Definitions, Explanations and Terminology
VALIDATE
The VALIDATE command is used to check for corrupt blocks and missing files, or to determine whether a backup set can be restored. If VALIDATE detects a problem during validation, then RMAN displays it and triggers execution of a failure assessment. This gives the user a better idea if a backed up database is restorable.
VTL
A virtual tape library (VTL) is a data storage virtualization technology used for backup and recovery purposes. A VTL is usually a hard disk storage device which presents itself as a physical tape library to backup software.