Skip to main content
E-Series Systems

Access NVMe volumes for physical NVMe device targets

Contributors netapp-driley netapp-jolieg

You can configure the I/O directed to the device target based on which OS (and by extension multipathing method) you are using.

For RHEL 8, RHEL 9, and SLES 15, I/O is directed to the physical NVMe device targets by the Linux host. A native NVMe multipathing solution manages the physical paths underlying the single apparent physical device displayed by the host.

Physical NVMe devices are I/O targets

It is best practice to run I/O to the links in /dev/disk/by-id/nvme-eui.[uuid#] rather than directly to the physical nvme device path /dev/nvme[subsys#]n[id#]. The link between these two locations can be found using the following command:

# ls /dev/disk/by-id/ -l
lrwxrwxrwx 1 root root 13 Oct 18 15:14 nvme-eui.0000320f5cad32cf00a0980000af4112 -> ../../nvme0n1

I/O run to /dev/disk/by-id/nvme-eui.[uuid#] will be passed directly through /dev/nvme[subsys#]n[id#] which has all paths virtualized underneath it using the Native NVMe multipathing solution.

You can view your paths by running:

# nvme list-subsys

Example output:

nvme-subsys0 -
+- nvme0 rdma traddr= trsvcid=4420 live
+- nvme1 rdma traddr= trsvcid=4420 live

If you specify a physical nvme device when using the 'nvme list-subsys' command, it provides additional information about the paths to that namespace:

# nvme list-subsys /dev/nvme0n1
nvme-subsys0 -
 +- nvme0 rdma traddr= trsvcid=4420 live non-optimized
 +- nvme1 rdma traddr= trsvcid=4420 live non-optimized
 +- nvme2 rdma traddr= trsvcid=4420 live optimized
 +- nvme3 rdma traddr= trsvcid=4420 live optimized

There are also hooks into the multipath commands to allow you to view your path information for native failover through them as well:

#multipath -ll
Note To view the path information, the following must be set in /etc/multipath.conf:
defaults {
        enable_foreign nvme

Example output:

eui.0000a0335c05d57a00a0980000a5229d [nvme]:nvme0n9 NVMe,Netapp E-Series,08520001
size=4194304 features='n/a' hwhandler='ANA' wp=rw
|-+- policy='n/a' prio=50 status=optimized
| `- 0:0:1 nvme0c0n1 0:0 n/a optimized    live
`-+- policy='n/a' prio-10 status=non-optimized
`- 0:1:1 nvme0c1n1 0:0 n/a non-optimized    live