ScaleStore VS xNVMe

I don't remember exactly why I have any of them saved, but these are some experimental data stores that seems to be fitting what you're looking for somewhat:

- https://github.com/DataManagementLab/ScaleStore - "A Fast and Cost-Efficient Storage Engine using DRAM, NVMe, and RDMA"

- https://github.com/unum-cloud/udisk - "The fastest ACID-transactional persisted Key-Value store designed for NVMe block-devices with GPU-acceleration and SPDK to bypass the Linux kernel."

- https://github.com/capsuleman/ssd-nvme-database - "Columnar database on SSD NVMe"

The linked blog post at the top of this article - https://muratbuffalo.blogspot.com/2023/01/is-scalable-oltp-i... - provides graphics that give extremely useful context. And here's the repo for the paper that discusses: https://github.com/DataManagementLab/ScaleStore

The idea that one of many writer-compute-nodes can literally reach into a memory buffer that is shared across machines, atomically flip some lock bits and propagate some cache-coherence messages, and use that to build a multi-writer distributed database without needing to partition (and where any writer-compute-node can handle any message, so you can just round-robin a firehose of messages at them)... and that there's a chance (though not yet implemented) that one could implement ACID on top of this? It's absolute madness, and wildly exciting.

Basically io_uring grew a lot, the latest API offers incredible tools but there are very few examples in any language (xnvme and fio), and in particular I'm struggling to understand how to do it in Rust: where should unsafe code stop? should I simply expose the io_uring api as unsafe, or should I do more work in C and present the ring when ready to rust?

The foundation of xNVMe is libxnvme, a user space library for working with NVMe devices. It provides a C API for memory management, that is, for allocating physical / DMA transferable memory when needed. An NVMe command interface allowing you to submit and complete NVMe commands in a synchronous as well as an asynchronous manner. Similar to libnvme, however, with a focus on I/O performance and portability. Thus, xNVMe and the libxnvme library works not just on Linux, but also on FreeBSD, Windows, and MacOS.