StorageGRID Webscale provides two mechanisms for protecting object data from loss: replication and erasure coding.
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What replication is
Replication is one of two mechanisms used by StorageGRID Webscale to store object data. When StorageGRID Webscale matches objects to an ILM rule that is configured to create replicated copies, the system creates exact copies of object data and stores the copies on Storage Nodes or Archive Nodes.
What erasure coding is
Erasure coding is the second method used by StorageGRID Webscale to store object data. When StorageGRID Webscale matches objects to an ILM rule that is configured to create erasure-coded copies, it slices object data into data fragments, computes additional parity fragments, and stores each fragment on a different Storage Node. When an object is accessed, it is reassembled using the stored fragments. If a data or a parity fragment becomes corrupt or lost, the erasure-coding algorithm can recreate that fragment using a subset of the remaining data and parity fragments.
What erasure coding schemes are
When you configure the Erasure Coding profile for an ILM rule, you select an available erasure coding scheme. Erasure coding schemes control how many data fragments and how many parity fragments are created for each object. The erasure coding schemes that are available depend on how many Storage Nodes and sites make up the storage pool you plan to use.
Advantages, disadvantages, and requirements for erasure coding
Before deciding whether to use replication or erasure coding to protect object data from loss, you should understand the advantages, disadvantages, and the requirements for erasure coding.