NVMe

NVM Express

Links

• nvmexpress.org
• arch linux nvme doc
• How to Deploy High-Performance Multi-Tenant Object Storage with NVMe

NVMe/TCP

• https://www.networkworld.com/article/3609921/nvme-over-tcp-how-it-supercharges-ssd-storage-using-standard-ip-networks.html
• nvme and tcp
• NVMe over TCP
• https://tekdeeps.com/what-is-nvme-over-tcp-how-to-use/
• https://www.linuxjournal.com/content/data-flash-part-iii-nvme-over-fabrics-using-tcp
• nvme-tcp storage operations

Qemu and NVMe

• Qemu and nvme

Hardware

Slots

M.2

The old way, on standard motherboards

U.2

Hotplug

• https://en.wikipedia.org/wiki/U.2

Tools

nvmet-cli

https://github.com/JunxiongGuan/nvmetcli

Documentation

NVMe device names

• NVME device names

Example: /dev/nvme0n2p3

Means nvme device 0, namespace 2, partition 3 The first namespace, n1, will always exist

Namespaces

MNAM: Maximum Number of Allowed Namespaces

• nvme namespaces
• Drew Thorstensen - NVME namespaces
• https://narasimhan-v.github.io/2020/06/12/Managing-NVMe-Namespaces.html

HOWTO

List devices

nvme list

get details

nvme id-ctrl /dev/nvme0

if you want to find for example IP of a device:

nvme list-subsys /dev/nvme2n1

Namespaces

List namespaces

nvme list-ns /dev/nvme1

Show info about namespace

nvme id-ns /dev/nvme1n1

Show number of available namespaces

nvme id-ctrl /dev/nvme1|grep nn

Show total capacity

nvme id-ctrl /dev/nvme1|grep tnvmcap

Show unallocated capacity

nvme id-ctrl /dev/nvme1|grep unvmcap

NVMe over fabrics

https://www.linuxjournal.com/content/data-flash-part-iii-nvme-over-fabrics-using-tcp

You might want to use nvmetcli on the target:

https://github.com/JunxiongGuan/nvmetcli

Dependencies: python3-configshell-fb

NVMe/TCP Host

See Configuring an NVMe/TCP host

Client

Modules:

nvme_tcp nvme_core nvme_fabrics and more

Show remote connections

nvme list-subsys

Monitoring nvme

• Monitoring nvme with zabbix

FAQ

Failed to open /dev/nvme-fabrics: No such file or directory

modprobe nvme-tcp

or maybe rdma

Failed to write to /dev/nvme-fabrics: Connection refused

dmesg will probably show

nvme0: failed to connect socket: -111

Maybe you're using something like infiniband, try

nvme discover -t rdma ...

Failed to write to /dev/nvme-fabrics: Invalid argument

nvme nvme0: Invalid MNAN value 1024

Try

modprobe nvme_core multipath=N

(remember to rmmod first :)