Veritas NetBackup™ Flex Scale Administrator's Guide
- Product overview
- Viewing information about the NetBackup Flex Scale cluster environment
- NetBackup Flex Scale infrastructure management
- User management
- Directory services and certificate management
- Region settings management
- About NetBackup Flex Scale storage
- Node and disk management
- License management
- NetBackup Flex Scale network management
- About network management
- Modifying DNS settings
- About bonding Ethernet interfaces
- Bonding operations
- Data network configurations
- NetBackup Flex Scale infrastructure monitoring
- Resiliency in NetBackup Flex Scale
- Site-based disaster recovery in NetBackup Flex Scale
- NetBackup Flex Scale security
- Troubleshooting
- Appendix A. Configuring NetBackup optimized duplication
- Appendix B. Disaster recovery terminologies
Erasure coding in NetBackup Flex Scale
Erasure coding (EC) offers a more robust solution in redundancy and fault tolerance for critical storage archives. As storage systems expand and become more complex, traditional data protection mechanisms prove to be inadequate against failures. In erasure coding, data is broken into fragments, expanded, and encoded with redundant data pieces and stored across different locations or storage media. When one or more disks fail, the data on failed disks is reconstructed using the parity information in the encoded disks and data in the surviving disks. Multiple nodes can read or write concurrently to an erasure coded volume without data corruption.
Erasure coding allows setting ratios of original data and coding data. With a ratio of m parts of original data to n parts of coding data, the code can tolerate the loss of any n parts and regenerate the original m parts. In NetBackup Flex Scale, the erasure coding ratio is 8:4. This means that every 8 parts of data are enriched with 4 parts of coding data and the data is spread across 12 (8 + 4) disks.
For example, when the deduplication engine receives 2MB of data from a backup image, the 2M stripe is ready to be erasure-coded. The deduplication engine uses the erasure-coded file system underneath to store this data. The data is divided into eight 256K data fragments. Four 256K parity fragments are created for resiliency. These fragments are then sent to the underlying storage which is distributed across nodes and disks.
Benefits of erasure coding:
Improved performance
NetBackup Flex Scale uses the I/O resources of the entire disk pool to ingest backup data, and hence, eliminates bottlenecks by limiting the data protection jobs to a single node's disks. Also, during data restore or when a failed disk is rebuilt, many disks contribute to the workload simultaneously by reading erasure coded data fragments.
High level of data protection
Erasure coding's distributed nature also provides a high level of data protection. Deployments with 4-6 nodes can protect against failure of a node and a disk or any two disks. Deployments with six or more nodes can protect against simultaneous failure of two nodes or any four disks (HDDs) in the disk pool or any two SSDs providing catalog storage.
High usable capacity
Advantages of using the erasure-coded data layout include a usable capacity of 67% for large capacity HDD on top of high performance and resiliency.
NetBackup Flex Scale requires a four-node base configuration for a deployment. When a new node is added, NetBackup Flex Scale ensures data is balanced across the nodes by intelligently moving the smallest possible amount of data to maintain or increase its existing resiliency characteristics.
The Reed-Solomon algorithm is used to build the erasure coding solution.