Computing data distribution for OceanStor 9000

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Data distribution for OceanStor 9000 is computed by CA using the HASH algorithm based on the FID of a file and the offset and length of the current operation.

Other related questions:
Computing data distribution when adding a new node to OceanStor 9000
Computing data distribution when adding a new node to OceanStor 9000: Data slices of OceanStor 9000 are achieved using Erasure Code. For details, see: - Information about data protection in OceanStor 9000 V100R001C01 Administrator Guide 11 - OceanStor 9000 V100R001 Erasure Code Multimedia 03

Distributing data slices evenly on each node of OceanStor 9000
Distributing data slices evenly on each node of OceanStor 9000: Data slices of OceanStor 9000 are achieved using Erasure Code. For details, see: - Information about data protection in OceanStor 9000 V100R001C01 Administrator Guide 11 - OceanStor 9000 V100R001 Erasure Code Multimedia 03

Computing Erasure Code for OceanStor 9000
Computing Erasure Code for OceanStor 9000: In a normal read/write process, Erasure Code is computed at the CA layer. In a data recovery process, Erasure Code is computed at the OBS layer.

OceanStor 9000 characteristics for high-performance computing
OceanStor 9000 provides the following characteristics for high-performance computing: - High performance: excellent I/O performance for meeting service requirements - High availability: a SPOF-free cluster system for high data reliability - Easy scalability: distributed architecture with full-symmetry node design for on-demand expansion of capacity and performance - Ease of maintenance: unified namespace for reduced maintenance cost

Principles and computing method of Erasure Code for OceanStor 9000
Erasure Code supports two data protection levels: N+M and N+M:B. N+M includes N+1, N+2, N+3, and N+4, and is suitable for scenarios with a large number of nodes. N+M:B includes N+2:1 and N+3:1, and is suitable for scenarios with a small number of nodes. N+M indicates that each data stripe contains N original data strips and M redundant data strips, ensuring high data integrity even when M nodes fail. N+M:B indicates that each data stripe contains N original data strips and M redundant data strips, ensuring high data integrity even when M disks or B nodes fail. Users only need to specify +M or +M:B for directories or files. OceanStor 9000 automatically selects the most appropriate N value based on the number of nodes. N ranges from 2 to 16, and M from 1 to 4. To configure the redundancy ratio: 1. Log in to DeviceManager. 2. Choose Provisioning > Resource Manager. 3. On the page that is displayed, select a directory and click Properties. 4. In the dialog box that is displayed, click the Redundancy Ratio tab and set +RDC/RDN. In N+M scenarios, data slices are stored on N nodes, and redundant data is stored on another M nodes. Among the N+M nodes, up to three are allowed to fail at the same time. However, N is within 2 to 16 and OceanStor 9000 supports a maximum of 288 nodes. Accordingly, some nodes (except the N+M nodes) do not store data slices, and the failure of these nodes, in theory, does not impact on data integrity. In N+M:B scenarios, data slices are stored on some disks of N nodes, and M pieces of redundant data are stored on other disks of the N nodes. The system allows up to M pieces of redundant data to be lost. That is, M disks are allowed to fail at the same time. Similarly, if more than B nodes fail, more than M pieces of redundant data will be lost. Therefore, a maximum of M disks or B nodes are allowed to fail.

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