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	<title>BT.Retention Engine - Revision history</title>
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	<updated>2026-05-06T14:45:06Z</updated>
	<subtitle>Revision history for this page on the wiki</subtitle>
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		<id>https://www.infra-repository.org/oiar-2013/index.php?title=BT.Retention_Engine&amp;diff=597&amp;oldid=prev</id>
		<title>Jan Schoonderbeek: start</title>
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		<updated>2012-11-11T23:22:21Z</updated>

		<summary type="html">&lt;p&gt;start&lt;/p&gt;
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{{Pageheaderbox4BBT&lt;br /&gt;
|name=Retention Engine&lt;br /&gt;
|WorkingArea=Storage (ST)&lt;br /&gt;
|version=0.92&lt;br /&gt;
|owner=J.A.H. Schoonderbeek&lt;br /&gt;
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A Retention Engine facility presents data retention functionality beyond the four basic operations (store/retrieve/modify/delete). It can thus be seen as &amp;quot;adding storage intelligence&amp;quot; to [[BT.Raw Retention|Raw Retention]] functionality, which itself provides the basic storage operations. However, this intelligence can be characterized as &amp;quot;back-end facing&amp;quot;: generally speaking the facility&amp;#039;s clients don&amp;#039;t have (direct) access to it, only the administrators and back-end systems.&lt;br /&gt;
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When present, the Retention Engine is positioned &amp;quot;between&amp;quot; the Raw Retention functionality and the clients that want to retain data or manipulate retained data. This means that the clients cannot &amp;quot;see&amp;quot; the data stored by the Raw Retention functionality directly. Instead, they &amp;quot;see&amp;quot; data as the Retention Engine presents it to them, while the data that&amp;#039;s actually stored on the Raw Retention facility may be different (e.g. split in different blocks and augmented with parity blocks, as happens when storing data on a RAID-5 storage device).&lt;br /&gt;
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Examples of Retention Engine operations are:&lt;br /&gt;
* adding and handling data redundancy;&lt;br /&gt;
* data integrity checking on retrieval/modification;&lt;br /&gt;
* data replication (usually to another instance of a Retention Engine);&lt;br /&gt;
* thin provisioning;&lt;br /&gt;
* snapshotting;&lt;br /&gt;
* meta-data reporting (e.g. space left on a physical or logical device).&lt;br /&gt;
Furthermore, the Retention Engine facility may handle integration with other storage-related facilities, such as [[BT.Backup+Restore|Backup &amp;amp; Restore]].&lt;br /&gt;
&lt;br /&gt;
Note that the storage intelligence that the Retention Engine brings acts on the lowest abstraction level for data, that of the &amp;quot;raw bits&amp;quot; level, manipulating sets of elementary data elements, such as the bits and bytes on a hard disk.&lt;br /&gt;
{{FunctionIcon&lt;br /&gt;
|image=Icon BBT Retention Engine.png&lt;br /&gt;
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		<author><name>Jan Schoonderbeek</name></author>
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