SK hynix and SanDisk release the first open High Bandwidth Flash (HBF) specification through the Open Compute Project to resolve AI inference bottlenecks. The standard defines 8-high and 16-high NAND stacks up to 512GB, utilizing UCIe interfaces to deliver bandwidths from 0.4 TB/s to 3.0 TB/s. Positioned between HBM and SSDs, HBF targets read-intensive workloads like Llama 3.1 model weights. While Google and Tenstorrent back the consortium, major players like NVIDIA and AMD have yet to adopt the technology.
HBF specification release
- ▪The HBF specification defines memory packages with capacities up to 512GB using either 8-high or 16-high NAND die stacks.
- ▪The HBF specification adopts the Universal Chiplet Interconnect Express (UCIe) standard as its physical and protocol-level host interface.
- ▪SK hynix and SanDisk released the first standard technical specification for High Bandwidth Flash (HBF) through the Open Compute Project (OCP) on August 4, 2026.
Performance tiers bandwidth capacity
- ▪The highest HBF performance grade of 3.0 TB/s is designed to compete with the memory bandwidth of a single HBM4 stack, which ranges from 2.0 TB/s to over 3.3 TB/s.
- ▪The HBF specification defines three performance grades with read bandwidth ranging from approximately 0.4 TB/s to 3.0 TB/s.
AI inference workload applications
- ▪A simulation by SanDisk using the Llama 3.1 405B model showed that HBF-based system performance was within 2.2% of a system with unlimited HBM capacity.
- ▪HBF is designed as an intermediate memory tier between High Bandwidth Memory (HBM) and enterprise SSDs to store read-intensive data like pretrained AI model weights.
SanDisk Gen 1 targets
- ▪SanDisk is targeting a first-generation HBF product with 1.6 TB/s of read bandwidth and 512GB of capacity using a 16-die stack.
- ▪SanDisk previously targeted the second half of 2026 for its first HBF samples, with commercialization targeted for 2027.
Consortium member participation
- ▪The HBF consortium was launched in February 2026, six months prior to the release of the first standard specification.
- ▪Google and Tenstorrent are participating in the HBF consortium alongside founding members SK hynix and SanDisk.
Adoption indicators dependencies
- ▪Major technology companies including AMD, Broadcom, Intel, NVIDIA, Marvell, Micron, Qualcomm, Samsung, and Western Digital have expressed no official interest in HBF.
- ▪The commercial success of HBF depends on whether accelerator vendors integrate required interfaces, software frameworks support efficient data placement, and sampled devices meet latency and power targets.
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