NVMe-oF host configuration for RHEL 8.6 with ONTAP

10/29/2024 Contributors

NVMe over Fabrics or NVMe-oF (including NVMe/FC and other transports) is supported with Red Hat Enterprise Linux (RHEL) 8.6 with ANA (Asymmetric Namespace Access). ANA is the asymmetric logical unit access (ALUA) equivalent in the NVMe-oF environment, and is currently implemented with in-kernel NVMe Multipath. During this procedure, you enable NVMe-oF with in-kernel NVMe Multipath using ANA on RHEL 8.6 and ONTAP as the target

See the NetApp Interoperability Matrix Tool for accurate details regarding supported configurations.

Features

RHEL 8.6 includes support for NVMe/TCP (as a Technology Preview feature) in addition to NVMe/FC. The NetApp plugin in the native nvme-cli package is capable of displaying ONTAP details for both NVMe/FC and NVMe/TCP namespaces.

Known limitations

For RHEL 8.6, in-kernel NVMe multipath remains disabled by default. Therefore, you need to enable it manually.
NVMe/TCP on RHEL 8.6 remains a Technology Preview feature due to open issues. Refer to the RHEL 8.6 Release Notes for details.
SAN booting using the NVMe-oF protocol is currently not supported.

Enable in-kernel NVMe Multipath

You can use the following procedure to enable in-kernel NVMe multipath.

Steps

Install RHEL 8.6 on the server. After the installation is complete, verify that you are running the specified RHEL 8.6 kernel. See the NetApp Interoperability Matrix for the most current list of supported versions.
After the installation is complete, verify that you are running the specified RHEL 8.6 kernel. See the NetApp Interoperability Matrix for the most current list of supported versions.

Example:
```
# uname -r
4.18.0-372.9.1.el8.x86_64
```

Install the nvme-cli package:

Example:

# rpm -qa|grep nvme-cli
nvme-cli-1.16-3.el8.x86_64

Enable in-kernel NVMe multipath:

# grubby --args=nvme_core.multipath=Y --update-kernel /boot/vmlinuz-4.18.0-372.9.1.el8.x86_64

On the host, check the host NQN string at /etc/nvme/hostnqn and verify that it matches the host NQN string for the corresponding subsystem on the ONTAP array. Example:

# cat /etc/nvme/hostnqn
nqn.2014-08.org.nvmexpress:uuid:9ed5b327-b9fc-4cf5-97b3-1b5d986345d1
::> vserver nvme subsystem host show -vserver vs_fcnvme_141
Vserver     Subsystem       Host NQN
----------- --------------- ----------------------------------------------------------
vs_fcnvme_14 nvme_141_1     nqn.2014-08.org.nvmexpress:uuid:9ed5b327-b9fc-4cf5-97b3-1b5d986345d1

If the host NQN strings do not match, you should use the vserver modify command to update the host NQN string on your corresponding ONTAP NVMe subsystem to match the host NQN string /etc/nvme/hostnqn on the host.

Reboot the host.

If you intend to run both NVMe and SCSI co-existent traffic on the same host, NetApp recommends using in-kernel NVMe multipath for ONTAP namespaces and dm-multipath for ONTAP LUNs respectively. This means that the ONTAP namespaces should be excluded from dm-multipath to prevent dm-multipath from claiming these namespace devices. This can be done by adding the enable_foreign setting to the /etc/multipath.conf file:

# cat /etc/multipath.conf
defaults {
        enable_foreign     NONE
}

Restart the multipathd daemon by running a systemctl restart multipathd command to allow the new setting to take effect.

Configure NVMe/FC

You can configure NVMe/FC for Broadcom/Emulex or Marvell/Qlogic adapters.

Broadcom/Emulex

Steps

Verify that you are using the supported adapter. See the NetApp Interoperability Matrix for the most current list of supported adapters.

# cat /sys/class/scsi_host/host*/modelname
LPe32002-M2
LPe32002-M2
# cat /sys/class/scsi_host/host*/modeldesc
Emulex LightPulse LPe32002-M2 2-Port 32Gb Fibre Channel Adapter
Emulex LightPulse LPe32002-M2 2-Port 32Gb Fibre Channel Adapter

Verify that you are using the recommended Broadcom lpfc firmware and inbox driver. See the NetApp Interoperability Matrix for the most current list of supported adapter driver and firmware versions.
```
# cat /sys/class/scsi_host/host*/fwrev
12.8.351.47, sli-4:2:c
12.8.351.47, sli-4:2:c
# cat /sys/module/lpfc/version
0:14.0.0.4
```

Verify that lpfc_enable_fc4_type is set to 3

# cat /sys/module/lpfc/parameters/lpfc_enable_fc4_type
3

Verify that the initiator ports are up and running, and that you can see the target LIFs.

# cat /sys/class/fc_host/host*/port_name
0x100000109b1c1204
0x100000109b1c1205
# cat /sys/class/fc_host/host*/port_state
Online
Online
# cat /sys/class/scsi_host/host*/nvme_info
NVME Initiator Enabled
XRI Dist lpfc0 Total 6144 IO 5894 ELS 250
NVME LPORT lpfc0 WWPN x100000109b1c1204 WWNN x200000109b1c1204 DID x011d00 ONLINE
NVME RPORT WWPN x203800a098dfdd91 WWNN x203700a098dfdd91 DID x010c07 TARGET DISCSRVC ONLINE
NVME RPORT WWPN x203900a098dfdd91 WWNN x203700a098dfdd91 DID x011507 TARGET DISCSRVC ONLINE

NVME Statistics
LS: Xmt 0000000f78 Cmpl 0000000f78 Abort 00000000
LS XMIT: Err 00000000 CMPL: xb 00000000 Err 00000000
Total FCP Cmpl 000000002fe29bba Issue 000000002fe29bc4 OutIO 000000000000000a
abort 00001bc7 noxri 00000000 nondlp 00000000 qdepth 00000000 wqerr 00000000 err 00000000
FCP CMPL: xb 00001e15 Err 0000d906

NVME Initiator Enabled
XRI Dist lpfc1 Total 6144 IO 5894 ELS 250
NVME LPORT lpfc1 WWPN x100000109b1c1205 WWNN x200000109b1c1205 DID x011900 ONLINE
NVME RPORT WWPN x203d00a098dfdd91 WWNN x203700a098dfdd91 DID x010007 TARGET DISCSRVC ONLINE
NVME RPORT WWPN x203a00a098dfdd91 WWNN x203700a098dfdd91 DID x012a07 TARGET DISCSRVC ONLINE

NVME Statistics
LS: Xmt 0000000fa8 Cmpl 0000000fa8 Abort 00000000
LS XMIT: Err 00000000 CMPL: xb 00000000 Err 00000000
Total FCP Cmpl 000000002e14f170 Issue 000000002e14f17a OutIO 000000000000000a
abort 000016bb noxri 00000000 nondlp 00000000 qdepth 00000000 wqerr 00000000 err 00000000
FCP CMPL: xb 00001f50 Err 0000d9f8

Marvell/QLogic FC adapter for NVMe/FC

The native inbox qla2xxx driver included in the RHEL 8.6 kernel has the latest upstream fixes. These fixes are essential for ONTAP support.

Steps

Verify that you are running the supported adapter driver and firmware versions:

# cat /sys/class/fc_host/host*/symbolic_name
QLE2742 FW:v9.06.02 DVR:v10.02.00.200-k
QLE2742 FW:v9.06.02 DVR:v10.02.00.200-k

Verify ql2xnvmeenable is set which enables the Marvell adapter to function as a NVMe/FC initiator using the following command:
```
# cat /sys/module/qla2xxx/parameters/ql2xnvmeenable
1
```

Enable 1MB I/O (Optional)

ONTAP reports an MDTS (Max Data Transfer Size) of 8 in the Identify Controller data. This means the maximum I/O request size can be up to 1MB. To issue I/O requests of size 1 MB for a Broadcom NVMe/FC host, you should increase the lpfc value of the lpfc_sg_seg_cnt parameter to 256 from the default value of 64.

These steps don't apply to Qlogic NVMe/FC hosts.

Steps

Set the lpfc_sg_seg_cnt parameter to 256:

cat /etc/modprobe.d/lpfc.conf

options lpfc lpfc_sg_seg_cnt=256

Run the dracut -f command, and reboot the host.
Verify that the expected value of lpfc_sg_seg_cnt is 256:
```
cat /sys/module/lpfc/parameters/lpfc_sg_seg_cnt
```

Configure NVMe/TCP

NVMe/TCP does not have auto-connect functionality. Therefore, if a path goes down and is not reinstated within the default time out period of 10 minutes, NVMe/TCP cannot automatically reconnect. To prevent a time out, you should set the retry period for failover events to at least 30 minutes.

Steps

Verify whether the initiator port can fetch the discovery log page data across the supported NVMe/TCP LIFs:

# nvme discover -t tcp -w 192.168.1.8 -a 192.168.1.51
Discovery Log Number of Records 10, Generation counter 119
=====Discovery Log Entry 0======
trtype: tcp
adrfam: ipv4
subtype: nvme subsystem
treq: not specified
portid: 0
trsvcid: 4420
subnqn: nqn.1992-08.com.netapp:sn.56e362e9bb4f11ebbaded039ea165abc:subsystem.nvme_118_tcp_1
traddr: 192.168.2.56
sectype: none
=====Discovery Log Entry 1======
trtype: tcp
adrfam: ipv4
subtype: nvme subsystem
treq: not specified
portid: 1
trsvcid: 4420
subnqn: nqn.1992-08.com.netapp:sn.56e362e9bb4f11ebbaded039ea165abc:subsystem.nvme_118_tcp_1
traddr: 192.168.1.51
sectype: none
=====Discovery Log Entry 2======
trtype: tcp
adrfam: ipv4
subtype: nvme subsystem
treq: not specified
portid: 0
trsvcid: 4420
subnqn: nqn.1992-08.com.netapp:sn.56e362e9bb4f11ebbaded039ea165abc:subsystem.nvme_118_tcp_2
traddr: 192.168.2.56
sectype: none
...

Verify that other NVMe/TCP initiator-target LIF combos can successfully fetch discovery log page data. For example:

# nvme discover -t tcp -w 192.168.1.8 -a 192.168.1.51
# nvme discover -t tcp -w 192.168.1.8 -a 192.168.1.52
# nvme discover -t tcp -w 192.168.2.9 -a 192.168.2.56
# nvme discover -t tcp -w 192.168.2.9 -a 192.168.2.57

Run nvme connect-all command across all the supported NVMe/TCP initiator-target LIFs across the nodes. Ensure you set a longer ctrl_loss_tmo timer retry period (for example, 30 minutes, which can be set through -l 1800) during the connect-all so that it would retry for a longer period of time in the event of a path loss. For example:
```
# nvme connect-all -t tcp -w 192.168.1.8 -a 192.168.1.51 -l 1800
# nvme connect-all -t tcp -w 192.168.1.8 -a 192.168.1.52 -l 1800
# nvme connect-all -t tcp -w 192.168.2.9 -a 192.168.2.56 -l 1800
# nvme connect-all -t tcp -w 192.168.2.9 -a 192.168.2.57 -l 1800
```

Validate NVMe-oF

You can use the following procedure to validate NVMe-oF.

Steps

Verify that in-kernel NVMe multipath is enabled:

# cat /sys/module/nvme_core/parameters/multipath
Y

Verify that the appropriate NVMe-oF settings (such as, model set to NetApp ONTAP Controller and load balancing iopolicy set to round-robin) for the respective ONTAP namespaces properly reflect on the host:
```
# cat /sys/class/nvme-subsystem/nvme-subsys*/model
NetApp ONTAP Controller
NetApp ONTAP Controller

# cat /sys/class/nvme-subsystem/nvme-subsys*/iopolicy
round-robin
round-robin
```

Verify that the ONTAP namespaces properly reflect on the host. For example:

# nvme list
Node           SN                    Model                   Namespace
------------   --------------------- ---------------------------------
/dev/nvme0n1   814vWBNRwf9HAAAAAAAB   NetApp ONTAP Controller   1

Usage                Format         FW Rev
-------------------  -----------    --------
85.90 GB / 85.90 GB  4 KiB + 0 B    FFFFFFFF

Verify that the controller state of each path is live and has proper ANA status. For example:

# nvme list-subsys /dev/nvme1n1
nvme-subsys1 - nvme-subsys0 - NQN=nqn.1992-08.com.netapp:sn.5f5f2c4aa73b11e9967e00a098df41bd:subsystem.nvme_141_1
\
+- nvme0 fc traddr=nn-0x203700a098dfdd91:pn-0x203800a098dfdd91 host_traddr=nn-0x200000109b1c1204:pn-0x100000109b1c1204 live inaccessible
+- nvme1 fc traddr=nn-0x203700a098dfdd91:pn-0x203900a098dfdd91 host_traddr=nn-0x200000109b1c1204:pn-0x100000109b1c1204 live inaccessible
+- nvme2 fc traddr=nn-0x203700a098dfdd91:pn-0x203a00a098dfdd91 host_traddr=nn-0x200000109b1c1205:pn-0x100000109b1c1205 live optimized
+- nvme3 fc traddr=nn-0x203700a098dfdd91:pn-0x203d00a098dfdd91 host_traddr=nn-0x200000109b1c1205:pn-0x100000109b1c1205 live optimized

Verify that the NetApp plug-in displays proper values for each ONTAP namespace device. For example:

# nvme netapp ontapdevices -o column
Device       Vserver          Namespace Path
---------    -------          --------------------------------------------------
/dev/nvme0n1 vs_fcnvme_141    /vol/fcnvme_141_vol_1_1_0/fcnvme_141_ns

NSID  UUID                                   Size
----  ------------------------------         ------
1     72b887b1-5fb6-47b8-be0b-33326e2542e2  85.90GB


# nvme netapp ontapdevices -o json
{
"ONTAPdevices" : [
    {
        "Device" : "/dev/nvme0n1",
        "Vserver" : "vs_fcnvme_141",
        "Namespace_Path" : "/vol/fcnvme_141_vol_1_1_0/fcnvme_141_ns",
        "NSID" : 1,
        "UUID" : "72b887b1-5fb6-47b8-be0b-33326e2542e2",
        "Size" : "85.90GB",
        "LBA_Data_Size" : 4096,
        "Namespace_Size" : 20971520
    }
  ]
}

Known issues

The NVMe-oF host configuration for RHEL 8.6 with ONTAP has the following known issues:

NetApp Bug ID	Title	Description
1479047	RHEL 8.6 NVMe-oF hosts create duplicate Persistent Discovery Controllers	On NVMe over Fabrics (NVMe-oF) hosts, you can use the "nvme discover -p" command to create Persistent Discovery Controllers (PDCs). When this command is used, only one PDC should be created per initiator-target combination. However, if you are running ONTAP 9.10.1 and Red Hat Enterprise Linux (RHEL) 8.6 with an NVMe-oF host, a duplicate PDC is created each time "nvme discover -p" is executed. This leads to unnecessary usage of resources on both the host and the target.

NetApp Bug ID

Title

Description

1479047

RHEL 8.6 NVMe-oF hosts create duplicate Persistent Discovery Controllers

On NVMe over Fabrics (NVMe-oF) hosts, you can use the "nvme discover -p" command to create Persistent Discovery Controllers (PDCs). When this command is used, only one PDC should be created per initiator-target combination. However, if you are running ONTAP 9.10.1 and Red Hat Enterprise Linux (RHEL) 8.6 with an NVMe-oF host, a duplicate PDC is created each time "nvme discover -p" is executed. This leads to unnecessary usage of resources on both the host and the target.

NVMe-oF host configuration for RHEL 8.6 with ONTAP

Creating your file...

Features

Known limitations

Enable in-kernel NVMe Multipath

Configure NVMe/FC

Enable 1MB I/O (Optional)

Configure NVMe/TCP

Validate NVMe-oF

Known issues