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White Paper

Unblocking the full potential of SSDs using zoned and key value namespaces

NVMe verification support for SSDs

This paper describes performance characteristics that enable the newly introduced zoned namespace (ZNS) SSDs and key-value (KV) namespace SSDs to outperform traditional block storage based SSDs. We illustrate the verification support that NVMe QVIP provides for verification of these SSDs, focusing on the generation of traffic for directed tests as well as stress testing using NVMe QVIP’s built in sequence library and APIs. Finally, we highlight the performance statistics measured by NVMe QVIP that are useful in analyzing SSD efficiency.

What are key value namespaces?

Key value namespaces are represented as a collection of variable-sized key-value pairs, instead of traditional logical blocks. These key-value pairs consist of a key which has a maximum size of 16 bytes and a value which is the actual data to be stored in the namespace.

Keys are used in order to access data in KV SSDs, instead of the logical block addresses in traditional block storage. This new mapping scheme eliminates the translation layers necessary to achieve mapping with physical block addresses.

In key-value storage, data is not fragmented into blocks but is stored as a continuous collection of bytes mapped with a unique key. When a key is deleted, data associated with it gets erased and the entire continuous physical space gets freed for future use. This relieves the negative impact of garbage collection on the performance of an SSD.