What is Storage Replication?


The method in which stored data is copied from one storage array to another
Can happen locally over a SAN or LAN or even to remote locations over a WAN
Deals with duplicating archived data. Also called file replication, data replication, and remote storage replication.
Advantages of Storage Replication
Improves reliability, fault tolerance, performance, and accessibility of data
Remote users can access data that is replicated to remote locations
Allows resources, information, software, and hardware to be shared with multiple systems
Different Types of Storage Replication
      Point-in-Time Replication
      Continuous Replication
      Synchronous Replication
      Asynchronous Replication
      Remote Replication
Point-in-Time Replication
      Point-In-Time (PPT) replication is one that is matching to the source per a precise time and date
      Tracks change between the source and PIT replication so that synchronization may happen
      Bitmaps are used. Bitmaps reference each block on the source volume to a bit within the bitmap.
Continuous Replication
      Synchronized with the source at continuous repeating intervals
      Can be asynchronous and synchronous
Synchronous Replication
      Doesn’t finalize transactions or commit data until it has been written to destination and source
      Makes sure all data remains consistent in both sites
      Expensive and slows down the speed of the primary system
      Either write data in both primary and secondary data drives or not at all
      Asynchronous Replication
      Data is written to the primary first, then the secondary system
      Better performance than synchronous replication, however prevention of data loss is not guaranteed
      Buffer size impacts consistency
      Remote Replication
      Replication that occurs to another site
      Must take latency and bandwidth into account
      Can happen via disk-buffered replication, storage array remote replication, or log shipping
      Why Storage Replication is Necessary
      Site Redundancy- a technique where a full duplicate of data present in computers in one location is replicated at a different location
      Both sites’ data is duplicated so in the event of a failure, data can be quickly restored
      Software upgrades are also enhanced since they can be performed at one site and not interfere with normal operations at the other site
      Replication Consistency
      Gained through consistency groups that are used for maintaining the integrity of data and uniformity across multiple volumes and sites
      Comprises whole systems such as middleware, application, and backend
      Makes sure no matter which resource is accessed, data remains the same
      Vanderburg, Eric. (2015). CompTIA Storage+ Quick Review Guide. McGraw Hill Education.
      Rouse, Margaret. (n.d.). Storage Replication. Retrieved from


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