For workloads with cold data present (no write within past 7 days), when enabled, EC encodes a strip of data blocks on different nodes and calculates parity. In the event of a host and/or disk failure, the parity can be leveraged to calculate any missing data blocks (decoding). In the case of DSF, the data block is an extent group and each data block must be on a different node and belong to a different vDisk.
Once parity is computed, the data block copies are removed and replaced with the parity information.
Workloads Recommended for Erasure Coding
- Write once, read many (WORM) workloads.
- File servers.
- Log servers.
- Email (depending on usage).
Workloads Not Ideal for Erasure Coding
- Anything write- or overwrite-intensive.
Example of Space Saving from Erasure Coding on 20 TiB Nodes
Administrators can change the replication factor for containers with EC-X enabled. This option provides greater flexibility to help customers to achieve their desired level of data protection during the application life cycle. Containers can transition efficiently between replication factor 2 and replication factor 3, enabling the system to create or remove a resulting parity block automatically without additional read-modify-write operations.
To learn more we suggest to start with the following URLs:
Nutanix Bible on Erasure Coding and other Data Transform features
Prism Web Console Guide on Erasure Coding
Tech TopX: Erasure Coding on Nutanix University YouTube channel