Ethernet SSDs Come to the Fore as Kioxia Starts Sampling

Kioxia America this week said (via BusinessWire) that it had started sampling of its first SSDs featuring an Ethernet interface compatible with the existing RoCEv2 networks. The drives feature a rather high 25 Gb/s throughput and promise to greatly simplify creation of all-flash arrays.  

With explosive data growth, datacenters face several major challenges they have to address: increase storage density per square meter, lower total cost of ownership of storage devices, and keep power consumption of their machines in check. Disaggregation of storage and compute can potentially help with the first two challenges: as compute components cost money and use space inside storage servers. There are numerous ways to disaggregate storage and compute and one of them is to use drives with an Ethernet interface that support the NVMe protocol. 

Kioxia has teamed up with such industry players as Marvell, Foxconn-Ingrasys, and Accton to build Ethernet SSDs along with Ethernet Bunch of Flash (EBOF) machines that accommodate them. All devices are currently available to interested parties. 

Kioxia’s Ethernet SSDs come in a 2.5-inch/15mm form-factor and carry 1920 GB, 3840 GB, or 7680 GB of usable NAND memory. The drives are based on Marvell 88SN2400 NVMe-oF SSD converter controllers and support single or dual 25GbE RoCEv2 RDMA connections. The SSDs are compliant with the NVMe 1.4 specification and use the NVMe-oF 1.1 protocol.  

The manufacturer says that each Ethernet SSD is capable of 670K IOPS random read performance at (4KB), which is comparable with today’s client SSDs. Kioxia says nothing about sequential read and write speeds of its Ethernet SSD, but a single 25GbE interface can provide bandwidth of up to 3.125 GB/s, in line with what typical enterprise-grade M.2-2280/M.2-22110 drives with a PCIe 3.0 x4 provide. Performance wise, the Ethernet SSDs can hardly impress, but since these are proof-of-concept devices that will be used for testing, they may just be good enough. As for capacity, 15.36 TB and 30.72 TB 2.5-inch SSDs have existed for years, so the new drives cannot provide a leading storage density. 

Kioxia’s Ethernet SSDs are meant for experimental 2U Ethernet Bunch of Flash (EBOF) storage appliances that incorporate 24 drives to offer an up to 600 Gb/s storage throughput. The appliances do not carry a CPU, DRAM, or HBA, but only contain a built-in Ethernet switch (designed by Marvell) featuring a 2.4 Tb/s connectivity throughput that can be split between network connectivity and daisy chaining additional EBOFs.  

EBOFs run Marvell EBOF SDK that leverage the SONiC network operating system and that features advanced discovery and management functions. 

“The native Ethernet SSD combined with our switches and controllers offer data centers an EBOF solution that lowers their total cost of ownership, increases performance and reduces power as compared to alternative JBOF solutions,”said Thad Omura, Vice President of Marketing of the Flash Business Unit at Marvell. 

Kioxia’s Ethernet SSDs are now available to select industry partners of the company. There is no word when the SSD maker as well as its partners are planning to release Ethernet SSDs as well as EBOFs commercially, but given mediocre capacities and performance the current drives offer, perhaps the company plans something more impressive for commercial deployments.