NVMe
NVM Express
Links
- nvmexpress.org
- arch linux nvme doc
- How to Deploy High-Performance Multi-Tenant Object Storage with NVMe
- NVMe-oF Host Configuration for SUSE Linux Enterprise Server 15 SP3 with ONTAP
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/
- Data in a Flash, Part III: NVMe over Fabrics Using TCP
- nvme-tcp storage operations
Qemu and NVMe
Hardware
Slots
M.2
The old way, on standard motherboards
U.2
Hotplug
Tools
nvme-cli
nvmetcli
NVMe target admin tool
https://github.com/JunxiongGuan/nvmetcli
Documentation
NVMe device names
Example: /dev/nvme0n2p3
Means nvme device 0, namespace 2, partition 3 The first namespace, n1, will always exist
NVMe multipathing
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 and NQN of a device:
nvme list-subsys /dev/nvme2n1
of just
nvme list-subsys
Show subnqn of device
nvme id-ctrl /dev/nvme1n2 | grep subnqn
Namespaces
Difference between size and capacity
nsze vs ncap flbas = blocksize
To check them in a namespace:
nvme id-ns /dev/nvme1n3 | egrep "nsze|ncap|flbas"
Get block size:
nvme id-ns /dev/nvme1n3 | grep "in use"
which gives like
lbaf 1 : ms:0 lbads:12 rp:0 (in use)
where lbads is the blocksize in 2^lbads, so in this case 2^12 = 4096
Create namespace
Get controller id
nvme id-ctrl /dev/nvme1 | grep cntlid
gives like
cntlid : 0x1
Create 100G namespace, -s (--nsze) and -c (--ncap) is number of blocks -b, --blocksize
nvme create-ns /dev/nvme1 -s 26214387 -c 26214387 -b 4096
TODO: what about --flbas instead of blocksize?
To actually use the namespace you need to to attach it first
nvme attach-ns /dev/nvme1
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-oF target
/bin/mount -t configfs none /sys/kernel/config/
Show active targets
?
NVMe/TCP Host
In this context Host means client/initiator
See Configuring an NVMe/TCP host
Client
Modules:
nvme_rdma nvme_core nvme_fabrics and more
Connect on boot
Check /etc/nvme/discovery.conf
systemctl enable nvmf-autoconnect.service
Show remote connections
nvme list-subsys
Monitoring nvme
Terms and acronyms
flbas
Formatted LBA Sizes
nlbaf
FAQ
Errors on client/host
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
Check dmesg
nvme nvme0: Invalid MNAN value 1024
Try
modprobe nvme_core multipath=N
(remember to rmmod first :)
nvme_fabrics: no handler found for transport drma.
Check your /etc/nvme/discover.conf, it should be rdma :)
nvmet_tcp: malformed ip/port passed: :4420
Maybe forgot to set addr_traddr ?
Duplicate cntlid 1 with nvme0
Make sure next connection is on new control id, /dev/nvme0x vs /dev/nvme1x TODO ??
??
