Zoned Storage

Higher Capacities, Lower TCO & Improved QoS

The Increasing demand for data center storage capacities

Data volumes created by enterprises, machines, and consumer-generated content continue to drive demand for data center storage capacities at petabyte, exabyte and even zettabyte scale. Today, large scale data infrastructure already uses tens of thousands of SSDs and HDDs. Managing the extreme scale of data in a cost-effective manner is quickly becoming a requirement.

Benefits of Zoned Storage for the Datacenter

Zoned Storage is an open source, standards-based initiative to enable data centers to scale efficiently for the zettabyte storage capacity era. There are two technologies behind Zoned Storage, Shingled Magnetic Recording (SMR) in HDDs and Zoned Namespaces (ZNS) in SSDs.

Zoned storage devices, such as ZNS SSDs are divided into zones, significantly simplifying the drive architecture and minimizing the need for complex data management. With a unified software stack, the host is able to intelligently place data in different zones which enables these key benefits:

Increased Capacities

Higher density and scale as virtually no over-provisioning is required

Reduced Cost

Significantly reduced DRAM requirements and fewer support logic functions are required

Improved QoS

With minimal garbage collection required, the device controller can respond quicker

Increased Endurance

Because the data is not constantly re-written, the endurance is improved

The act of implementing Zone Storage on the host allows the system software and hardware to work together more efficiently by eliminating the multiple (duplicated) levels of indirection required for logical to physical mapping between the host and the SSD controller and the file system to the device. ZNS also reduces the need for over-provisioning and removes the issues associated with write amplification and QoS variability. In short ZNS addresses the issues of scale, QoS and TCO which hinder conventional SSDs.

Zoned Storage enables cost effective storage scaling for the zettabyte age

Zoned Storage consists of SMR for HDDs and ZNS for SSDs. Zoned Named Spaces is an extension of the NVMe™ standard. This technology allows us to offer SSDs that are zoned similarly to SMR HDDs, thereby allowing HDD and SSD storage to be seen as though it were one technology. Zoned Storage leverages both SMR and ZNS technologies and open source standards to enhance data center scaling.

With a unified software framework, data can be intelligently placed on both SMR HDDs and ZNS SSDs to increase storage capacity, lower TCO and improve QoS. With Zoned Storage, data center and cloud providers can more cost effectively scale storage for the zettabyte age.

Conventional

Device controls data placement

Zoned

Applications control data placement in zones

Achieving Increased Capacities Through Zoned Storage

Introduction

Challenges for Conventional SSDs

With traditional storage, data is placed on a drive as it arrives. As more-and-more data is written and deleted, data management is required. These necessary actions can tax the drive and negatively impact QoS, limit device density and add cost. For example, in an SSD, data management includes:

Write Amplification

The Same host data is rewritten multiple times as the data is moved on the drive

DRAM Requirments

Large Quantities needed to manage incoming data caching and logical to physical mapping

Garbage Collection

Moving, recombining and deleting data to better organize the data

Over Provisioning

Reserving storage space for internal garbage collection

ZNS

What is ZNS?

ZNS is an acronym for Zoned Namespaces. It is a NVM Express Consortium standard for zoning SSDs. Back in 2018, the synergies between the raw NAND flash erase block constraints and that of SMR HDDs were readily apparent. In a desire to create a standard for zoning SSDs, similar to SMR HDDs, Western Digital proposed the concept of Zoned Namespaces. ZNS extends the existing SMR HDD zone model to beneﬁt from the mature zone storage stack in Linux and other software ecosystems. By leveraging a common software infrastructure, both ZNS and SMR devices can be incorporated into data center and enterprise systems. All of the data management tasks that are problematic for an SSD controller to handle internally can be addressed if these tasks are instead handled by the host system. The architecture of a ZNS SSD yields the following benefits: