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| <title>Multi-Tier Storage - Apache Ignite</title> |
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| content="Apache Ignite multi-tier storage uses memory, disk, and Intel Optane as active storage tiers to |
| provide the speed of memory with the consistency of disk-based databases without the need for memory |
| warm-ups on restarts."/> |
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| <div class="container"> |
| <h1>Apache Ignite <strong>Multi-Tier Storage</strong></h1> |
| </div> |
| </header> |
| <div class="container"> |
| |
| <p> |
| Apache Ignite® is designed to work with memory, disk, and Intel Optane as active storage tiers. |
| The memory tier allows using DRAM and Intel® Optane™ operating in the Memory Mode for data storage |
| and processing needs. The disk tier is optional with the support of two options -- you can |
| persist data in an external database or keep it in the Ignite native persistence. SSD, Flash, |
| HDD, or Intel Optane operating in the AppDirect Mode can be used as a storage device. |
| </p> |
| |
| <img class="img-responsive diagram-right" src="/images/svg-diagrams/ignite_cluster.svg" alt="Apache Ignite Multi-Tier Storage diagram" /> |
| <p> |
| Ignite takes full control of its memory tier by allocating and managing off-heap regions. Each Ignite |
| server node allocates memory regions during bootstrap, splits the regions into pages, and keeps data |
| records with indexes in those pages. Java heap is used to keep temporary objects such as query result |
| sets, metrics samples, and objects generated by your application code. All these objects are garbage |
| collected eventually. |
| </p> |
| <p> |
| If you select native persistence as the disk tier, then most of the processing will still take place |
| in memory on cached data, but with a full copy stored on disk. If any record is missing in memory, |
| Ignite will read it from disk, allowing you to persist much larger data sets than you can cache in memory. |
| This also eliminates the need for time-consuming memory warm-ups on restarts. As soon as your cluster |
| reconnects after a restart, Ignite will serve most of the data from disk warming up the memory tier in |
| the background. |
| </p> |
| |
| <h2>Multi-Tier Storage Usage Modes</h2> |
| |
| <table class="table table-bordered table-striped" name="Deployment Options Features"> |
| <thead> |
| <tr> |
| <th width="35%" class="left">Mode</th> |
| <th>Description</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td class="left">In-Memory</td> |
| <td> |
| <p> |
| The whole data set is available in memory only. In order to survive node failures, we |
| recommend keeping at least one backup copy of the data in the cluster. DRAM or |
| Intel® Optane™ operating in the Memory Mode can be used as a storage device. |
| </p> |
| |
| <p> |
| <strong>Use cases</strong>: General in-memory caching, high-performance |
| computing, web-session caching, real-time processing of continuous data streams. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td class="left">In-Memory + External Database</td> |
| <td> |
| <p> |
| Ignite is deployed as a distributed caching layer on top of an existing external database. |
| This mode is for accelerating disk-based databases and your services with APIs that |
| interact with them. |
| </p> |
| |
| <p> |
| <strong>Use cases</strong>: Acceleration of services and APIs with write-through and |
| write-behind capability, to an external database. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td class="left">In-Memory Cache + Native Persistence</td> |
| <td> |
| <p> |
| 100% of data is persisted to disk, and the same or smaller amount is cached in memory. The |
| more data is cached, the faster is the performance. The disk serves as the primary storage |
| that survives any cluster failures and restarts. There is no need for memory warm-ups on |
| restarts since Ignite can serve data from disk. SSD, Flash, HDD or Intel® Optane™ operating |
| in the AppDirect Mode can be used as a storage device. |
| </p> |
| |
| <p> |
| <strong>Use cases</strong>: Ignite as an in-memory database or digital integration hub |
| with the active persistence layer. |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| |
| <h2 id="partitioning"> |
| Partitioning & Replication |
| </h2> |
| <p> |
| Depending on the configuration, Ignite can both partition or replicate data across the cluster. In the |
| replicated mode, each cluster node keeps a full copy of the data, but the size of a replicated cache is |
| limited by the amount of memory available on the node. In the partitioned mode, Ignite spreads the data |
| across all the cluster nodes evenly, allowing you to store much more than what can fit in a single machine. |
| </p> |
| |
| <h2 id="durability"> |
| Durability and Consistency |
| |
| </h2> |
| <p> |
| Ignite provides the following ACID guarantees across the cluster: |
| </p> |
| |
| <ul > |
| <li>Committed transactions always survive failures.</li> |
| <li> |
| The cluster can always be recovered to the latest successfully committed transaction. |
| </li> |
| </ul> |
| |
| |
| <h2 id="write-ahead-log"> |
| Write-Ahead Logging and Checkpointing |
| |
| </h2> |
| <p> |
| If Ignite native persistence is selected as a disk tier, then every time a record is updated in memory, |
| the change is added to the write-ahead log (WAL). The purpose of the WAL is to propagate updates to disk |
| in the fastest way possible and provide a consistent recovery mechanism that supports full cluster failures. |
| </p> |
| |
| <p> |
| As the WAL grows, it periodically gets checkpointed to the main storage. Checkpointing is the process of |
| copying dirty pages from the memory tier to the partition files on disk. A dirty page is a page that was |
| updated in memory, was appended to WAL, but was not written to the respective partition file on disk yet. |
| </p> |
| |
| <div class="jumbotron jumbotron-fluid"> |
| <div class="container"> |
| <div class="display-6 title">Learn More</div> |
| <hr class="my-4"> |
| <div class="row"> |
| <div class="col-sm-6"> |
| <ul> |
| <li> |
| <p><a href="https://cwiki.apache.org/confluence/display/IGNITE/Ignite+Durable+Memory+-+under+the+hood" target="docs">Multi-Tier Storage Implementation Details <i class="fa fa-angle-double-right"></i></a></p> |
| </li> |
| <li> |
| <p><a href="/arch/persistence.html"> Native Persistence <i class="fa fa-angle-double-right"></i></a></p> |
| </li> |
| <li> |
| <p><a href="/use-cases/datagrid.html"> Ignite as an In-Memory Data Grid <i class="fa fa-angle-double-right"></i></a></p> |
| </li> |
| </ul> |
| </div> |
| <div class="col-sm-6"> |
| <ul> |
| <li> |
| <p><a href="/use-cases/in-memory-database.html"> Ignite as an In-Memory Database <i class="fa fa-angle-double-right"></i></a></p> |
| </li> |
| <li> |
| <p><a href="/use-cases/digital-integration-hub.html"> Ignite as a Digital Integration Hub <i class="fa fa-angle-double-right"></i></a></p> |
| </li> |
| <li> |
| <p><a href="/use-cases/hpc.html"> Ignite for High Performance Computing <i class="fa fa-angle-double-right"></i></a></p> |
| </li> |
| </ul> |
| </div> |
| </div> |
| </div> |
| </div> |
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