===== Durability =====
[[dido:public:ra:xapend:xapend.a_glossary:start| Return to Glossary ]]

**Durability** is responsible for maintaining historical data between services and providing historical data to late joining applications. Specifies if [[dido:public:ra:xapend:xapend.a_glossary:s:sample|Samples]] should outlive their [[dido:public:ra:xapend:xapend.a_glossary:d:data_writer|Data Writers]] for late joiners. The longer a sample lives the greater the overhead passed to the [[dido:public:ra:xapend:xapend.a_glossary:d:dds]] becomes as it moves from dropping samples, to keeping them in shared memory, and to writing them to hard disk. Provided variants include:
  * ** Volatile** \\
  <wrap>No need to keep Samples for late joining [[dido:public:ra:xapend:xapend.a_glossary:d:data_reader]].</wrap> 
  * **Transient Local**  \\
  <wrap>Data [[dido:public:ra:xapend:xapend.a_glossary:i:instance|instance]] availability for late joining data reader is tied to the DataWriter availability.</wrap>
  * **Transient** \\
  <wrap>Data sample [[dido:public:ra:xapend:xapend.a_glossary:a:availability|availability]] outlives the data writer.</wrap>
  * **Persistent** \\
  <wrap>Data sample availability outlives system restarts.</wrap>
    
Source: [[https://istkb.adlinktech.com/article/vortex-opensplice-dds-glossary/ | OpenSplice Glossary]]



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