What Are the Ways to Implement Snapshot? What Are Differences Between Them? How Does the OceanStor 9000 Implement Snapshot?


Copy On Write (COW) and Redirect On Write (ROW) are the two ways to implement snapshot.

COW copies data objects protected by a snapshot to other locations or objects before replacing these data objects with new data, so that the original data objects serve as snapshot data.

ROW writes new data to new locations or objects, instead of replacing the original data protected by a snapshot.

The OceanStor 9000 implements the snapshot function based on metadata COW and data ROW.

Other related questions:
Principles of quick data recovery using OceanStor 9000 V100R001C01
Based on the load balancing policy and data protection levels, OceanStor 9000 divides storage resources into multiple logical groups, and each disk may belong to multiple logical groups. A logical group is an independent unit for data protection and recovery. A data protection level is assigned to each logical group (for example, 4+2). If a disk failure triggers data recovery, all logical groups to which the failed disk belongs will take part in data recovery concurrently. Therefore, the recovery speed is faster than that of a traditional RAID group. If a node failure triggers data recovery, logical groups to which all disks of the failed node belong will take part in data recovery concurrently. The maximum recovery speed is 1 TB/hour.

Differences between traffic policing and traffic shaping for S series switches
Traffic policing monitors the rate of traffic entering a network, and discards excess traffic to limit the traffic within a specified range and to protect network resources as well as user benefits. Traffic shaping proactively adjusts the rate of outgoing traffic to reduce traffic bursts, so that outgoing traffic can be transmitted at a stable rate, preventing traffic congestion on downstream devices. In most cases, traffic policing is applied to the inbound direction of a device, while traffic shaping is applied to the outbound direction of a device.

Differences between OceanStor 9000 V100R001C01 and V100R001C30
OceanStor 9000 V100R001C30 has much improved performance and functions compared to OceanStor 9000 V100R001C01. Node types and performance have also been enhanced. OceanStor 9000 V100R001C30 supports up to 60 PB for a cluster. In OceanStor 9000 V100R001C30, some new value-added features are introduced, such as InfoStamper, InfoReplicator, InfoLocker, NDMP backup, remote file synchronization, and video surveillance.

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