♜Strategic Management: Disaster Recovery Plan [DSP] (Definitions)

"A plan that establishes technical and organizational measures in order to face events or incidents with potentially huge impact that could even lead to the unavailability of data centers. The DRP development defines and ensures IT emergency procedures that intervene and protect the data relevant for the company activities and services. DRP is usually considered as the only part of the BCP in banking business continuity initiatives." (Vincenzo Morabito & Gianluigi Viscusi, "Information Technology Business Continuity", 2009)

"Generally a plan for enabling an organization to move to alternate system, network, and operational facilities in the event of an incident making the primary facilities unusable." (C Warren Axelrod, "Responsibilities and Liabilities with Respect to Catastrophes", 2009)

"A contingency plan that goes into effect after a full disaster occurs, used to reestablish basic capabilities and resources." (Annetta Cortez & Bob Yehling, "The Complete Idiot's Guide® To Risk Management", 2010)

"A written plan that explains how a company will recover its IT operations after a natural or man-made disaster that causes data or hardware loss." (Faithe Wempen, "Computing Fundamentals: Introduction to Computers", 2015)

"A plan developed to help a company recover from a disaster. It provides procedures for emergency response, extended backup operations, and post-disaster recovery when an organization suffers a loss of computer processing capability or resources and physical facilities." (Shon Harris & Fernando Maymi, "CISSP All-in-One Exam Guide" 8th Ed., 2018)

"Plans that document the steps you can take to replace damaged or destroyed components due to a disaster to restore the integrity of your IT infrastructure. " (Weiss, "Auditing IT Infrastructures for Compliance" 2nd Ed., 2015)

"A written plan for processing critical applications in the event of a major hardware or software failure or destruction of facilities." (NIST SP 800-82 Rev. 2)

"A written plan for recovering one or more information systems at an alternate facility in response to a major hardware or software failure or destruction of facilities." (NIST SP 800-34 Rev. 1)

"Management policy and procedures used to guide an enterprise response to a major loss of enterprise capability or damage to its facilities. The DRP is the second plan needed by the enterprise risk managers and is used when the enterprise must recover (at its original facilities) from a loss of capability over a period of hours or days." (CNSSI 4009-2015)

📦Data Migrations (DM): What is Data Migration?

Data Migrations Series

If you are working in a data-centric business it’s almost impossible for the average worker not to have heard this term, even tangentially. Considering the meaning of “migration” - the act or process of moving from one place to another - the intuition might even tell what data migration is about: the process of moving data from one place to another. It’s pretty basic, isn’t it? Now as data are moved over and over again between various places, for example the various layers of an applications, between databases, between media storage devices, and so on, we need some precision in defining the term because not all these can be considered as data migration examples. Actually we can talk about data copying or data movement without speaking of data migration. So, what is data migration? Here are a few takes on defining data migration:

“process of transferring data from one platform or operating system to another” (Babylon)

"Data migration is the process of transferring data between storage types, formats, or computer systems." (Wikipedia)

 "Data migration is the movement of legacy data to new media and technologies as the older ones are displaced." (Toolbox)

 “The purpose of data migration is to transfer existing data to the new environment.” (Talend)

 “Data Migration is the process of moving data from one or more sources into a target application” (Utopia Inc.)

 “[…] is the one off selection, preparation and transportation of appropriate data, of the right quality, to the right place, at the right time.” (J. Morris)

Resuming the above definitions, data migration can be defined as “the process of selecting, assessing, converting, preparing, validating and moving data from one or more information systems to another system”. The definition isn’t at all perfect, first of all because some of the terms need further explanation, secondly because any of the steps may be skip or other important steps can be identified in the process, and thirdly because further clarifications are needed. Anyway, it offers some precision, and at least for this reason, could be preferred to the above definitions.

So, resuming, data migration supposes the movement of data from one or more information systems, referred as source systems, to another one, the target system. Typically the new system replaces the old systems, they being retired, or they can continue to be used with reduced scope, for example for reporting purposes or . Even if performed in stages, the movement is typically one time activity, so everything has to be perfect. That’s the purpose of the other steps – to minimize the risks of something going wrong. The choice of steps and their complexity depends on the type of information systems involved, on the degree of resemblance between source and target, business needs, etc.

As mentioned above, not everything that involves data movement can be considered as data migration. For example data integration involves the movement and combination of data from various information systems in order to provide a unified view. Data synchronization involves the movement of data in order to reflect the changes of data in one information system into another, when data from the two systems need to be consistent. Data mirroring involves the synchronization of data, though it involves an exact copy of the data, the mirroring occurring continuously in real time. Data backup involves the movement/copy of data at a given point in time for eventual restore in case of data loss. Data transfer refers to the movement of row data between the layers of information systems. To make things even fuzzier, these types of data movements can be considered in a data migration too, as data need to be locally integrated, synchronized, transferred, mirrored or back up. Data migration is overall a complex thematic.

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🛢DBMS: Restore (Definitions)

"To restore an entire database and transaction log, database file(s), or a transaction log from a backup." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"This is the process of bringing a database back to a stable condition after a disaster." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

[point-in-time restore:] "Recovering only the transactions within a log backup committed before a specific point in time, instead of recovering the entire backup." (Victor Isakov et al, "MCITP Administrator: Microsoft SQL Server 2005 Optimization and Maintenance (70-444) Study Guide", 2007)

"The process of reinstating archived information onto your database server." (Robert D. Schneider and Darril Gibson, "Microsoft SQL Server 2008 All-In-One Desk Reference For Dummies", 2008)

"A multi-phase process that copies all the data and log pages from a specified backup to a specified database (the data-copy phase) and rolls forward all the transactions that are logged in the backup (the redo phase). At this point, by default, a restore rolls back any incomplete transactions (the undo phase), which completes the recovery of the database and makes it available to users." (Microsoft, "SQL Server 2012 Glossary", 2012)

"To rebuild a damaged or corrupted database or table space from a backup image produced with the backup database utility." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

🛢DBMS: Backup (Definitions)

"(1) A system, component, file, procedure, or person available to replace or help restore a primary item in the event of a failure or externally caused disaster. (2) To create or designate a system, component, file, procedure, or person as in (1)." (IEEE, "IEEE Standard Glossary of Software Engineering Terminology", 1990)

"A copy of a database or transaction log, used to recover from a media failure." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"A copy of a database, transaction log, file, or filegroup. Use this object to recover data after a system failure." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A spare copy of a file or files that have been created in case the original data is damaged or lost." (Andy Walker, "Absolute Beginner’s Guide To: Security, Spam, Spyware & Viruses", 2005)

"Making copies of data to a device other than the original data store." (Tom Petrocelli, "Data Protection and Information Lifecycle Management", 2005)

"This is a copy of a database that can be used to bring the database back to a stable condition in the event of a disaster." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"The process of copying your database’s information to another form of media, such as tape or disk. A good backup strategy is vital for any production SQL Server environment." (Robert D Schneider & Darril Gibson, "Microsoft SQL Server 2008 All-in-One Desk Reference For Dummies", 2008)

"(1) The process of making a copy of data from a database to ensure its continued availability in the event of a hardware or software failure requiring recovery of the database to restore the data. (2) The copy itself." (Craig S Mullins, "Database Administration", 2012)

"A duplicate of a program, a disk, or data, made either for archiving purposes or for safeguarding files." (Microsoft, "SQL Server 2012 Glossary", 2012)

"A utility that copies databases, files, or subsets of databases and files to a storage medium. This copy can be used to restore the data in case of system failure." (Marcia Kaufman et al, "Big Data For Dummies", 2013)

"A complete spare copy of data for purposes of disaster recovery. Backups are nonindexed mass storage and cannot substitute for indexed, archived information that can be quickly searched and retrieved (as in archiving)." (Robert F Smallwood, "Information Governance: Concepts, Strategies, and Best Practices", 2014)

"A copy of a database or table space that can be stored on a different medium and used to restore the database or table space in the event of failure or damage to the original." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

"Copying data to protect against loss of integrity or availability of the original." (ITIL)

🛢DBMS: Transaction Log Backup (Definitions)

 "A backup of the transaction log that flushes the transactions from the transaction log to a file. To have transaction log backup integrity, each consecutive file must not break the LSN chain." (Allan Hirt et al, "Microsoft SQL Server 2000 High Availability", 2004)

"A backup of transaction logs that includes all log records not backed up in previous log backups. Log backups are required under the full and bulk-logged recovery models and are unavailable under the simple recovery model." (SQL Server 2012 Glossary, "Microsoft", 2012)

"This type of backup makes a copy of all transactions in the transaction log, and it can clear all the inactive transactions from the log, thus giving the log more space to hold new transactions." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"A backup of transaction logs that includes all log records not backed up in previous log backups. Log backups are required under the full and bulk-logged recovery models and are unavailable under the simple recovery model." (Microsoft, "SQL Server 2012 Glossary", 2012)

"Special database backups that contain a sequential record of all data modifications that have occurred within a database. Transaction log backups can be used to perform point-in-time recovery. See also point-in-time recovery." (Mark Rhodes-Ousley, "Information Security: The Complete Reference, Second Edition, 2nd Ed.", 2013)

🛢DBMS: Full Backup (Databases)

"A complete point-in-time backup of a database." (Allan Hirt et al, "Microsoft SQL Server 2000 High Availability", 2004)

"A backup of the entire hard drive or array." (Tom Petrocelli, "Data Protection and Information Lifecycle Management", 2005)

"This is a type of backup that backs up the entire database, but not the transaction logs." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"A backup of the entire database that includes the database files, the locations of those files, and the portions of the transaction log (from the LSN recorded at the start of the backup to the LSN at the end of the backup). This is the first type of backup you will need to do in any backup strategy because all the other backup types depend on the existence of a full backup. A full backup is sometimes called a baseline in a backup strategy." (Marilyn Miller-White et al, "MCITP Administrator: Microsoft® SQL Server™ 2005 Optimization and Maintenance 70-444", 2007)

"A full backup backs up the complete database. This includes all data, all objects, and all files. A full backup also backs up the transaction log, but does not truncate it. Both differential and transaction log backups need to have a full backup done first." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"As its name implies, this type of backup archives all information within a database. Should the database be lost or damaged, you can restore it to its state as of the time you created the full backup. See also full differential backup; partial backup; restore." (Robert D Schneider & Darril Gibson, "Microsoft SQL Server 2008 All-in-One Desk Reference For Dummies", 2008)

"A backup of an entire database." (SQL Server 2012 Glossary, "Microsoft", 2012)

"A backup operation that backs up all files and sets their archive attribute to Off." (Faithe Wempen, "Computing Fundamentals: Introduction to Computers", 2015)

🛢DBMS: Incremental Backup (Definitions)

"Backups that only copy objects that have changed since the last backup." (Tom Petrocelli, "Data Protection and Information Lifecycle Management", 2005)

"A database backup containing only the data that has changed since the last full backup or incremental copy was made." (Craig S Mullins, "Database Administration", 2012)

"A backup that saves files that have changed since the last backup. When data is backed up, the archive bit on a file is turned off, and when changes are made to the file, the archive bit is set again. An incremental backup uses this information to only back up files that have changed since the last backup. An incremental backup turns the archive bit off again, and the next incremental backup backs up only the files that have changed since the last incremental backup. This sort of backup saves time, but it means that the restore process will involve restoring the last full backup and every incremental backup made after it." (Mark Rhodes-Ousley, "Information Security: The Complete Reference, Second Edition, 2nd Ed.", 2013)

"A backup operation that backs up all files that have the archive attribute set to On and then sets the attribute to Off." (Faithe Wempen, "Computing Fundamentals: Introduction to Computers", 2015)

"A copy of all database data that has changed since the most recent successful full backup operation. An incremental backup is also known as a cumulative backup image because each incremental backup includes the contents of the previous incremental backup." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

🛢DBMS: Differential Backup (Definitions)

"A database backup that records only pages that have changed in the database since the last full database backup. A differential backup is smaller and faster to restore than a full backup and has minimal effect on performance." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"This type of database backup records only those changes made to the database since the last full database backup. A differential backup is smaller, and is faster to restore than a full backup and has minimal effect on performance." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A type of database backup that only backs up changes made to the database since the last full database backup." (Allan Hirt et al, "Microsoft SQL Server 2000 High Availability", 2004)

"This is a type of backup that backs up changes to the database only since the last full backup was made." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"A backup type that backs up all the changes since the last full backup. Since the differential backup only backs up the changes, it can be done much quicker than a full backup. A possible backup strategy might include performing a full backup once a week and doing differential backups daily." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"A backup containing only changes made to the database since the preceding data backup on which the differential backup is based." (Microsoft, "SQL Server 2012 Glossary", 2012)

"A database backup operation that copies only the database pages that have been modified since the last full database backup." (Mark Rhodes-Ousley, "Information Security: The Complete Reference, Second Edition" 2nd Ed., 2013)

"Like an incremental backup, but only backs up files with the archive bit set—files that have changed since the last backup. Unlike the incremental backup, however, it does not reset the archive bit. Each differential backup backs up all files that have changed since the last backup that reset the bits. Using this strategy, a full backup is followed by differential backups. A restore consists of restoring the full backup and then only the last differential backup made." (Mark Rhodes-Ousley, "Information Security: The Complete Reference, Second Edition, 2nd Ed.", 2013)

"A backup operation that backs up all files that have the archive attribute set to On but does not change that attribute." (Faithe Wempen, "Computing Fundamentals: Introduction to Computers", 2015)

[delta backup:] "A copy of all database data that has changed since the last successful backup (full, incremental, or delta) of the table space in question. A delta backup is also known as a differential, or noncumulative, backup image. The predecessor of a delta backup image is the most recent successful backup that contains a copy of each of the table spaces in the delta backup image." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

🌁Software Engineering: Failover (Definitions)

"The process in which, in response to a node or resource failure, resources in a cluster switch ownership and start on another node in the server cluster. This term applies to a server cluster/failover cluster combination only. In log shipping implementations, the similar terms switch and role change are used to describe the change in ownership that occurs between primary and secondary servers." (Allan Hirt et al, "Microsoft SQL Server 2000 High Availability", 2004)

"The ability of a secondary device to take the place of a primary device during failure of the primary device." (Tom Petrocelli, "Data Protection and Information Lifecycle Management", 2005)

"The process that allows a secondary member of a replica set to become primary in the event of a failure." (MongoDb, "Glossary", 2008)

"A backup operation that automatically switches to a standby system if the primary system fails or is taken offline. It is an important fault-tolerant function that provides system availability." (Shon Harris & Fernando Maymi, "CISSP All-in-One Exam Guide" 8th Ed., 2018)

"An automatic operation that switches to a redundant or standby system or node in the event of a software, hardware, or network interruption. See also failback." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)