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NVMe-oF host configuration for RHEL 8.7 with ONTAP

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NVMe over Fabrics or NVMe-oF (including NVMe/FC and other transports) is supported with Red Hat Enterprise Linux (RHEL) 8.7 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 8.7 and ONTAP as the target.

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

Features

RHEL 8.7 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 8.7, in-kernel NVMe multipath remains disabled by default. Therefore, you need to enable it manually.

  • NVMe/TCP on RHEL 8.7 remains a Technology Preview feature due to open issues. Refer to the RHEL 8.7 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

  1. Install RHEL 8.7 on the server.

  2. After the installation is complete, verify that you are running the specified RHEL 8.7 kernel. See the NetApp Interoperability Matrix for the most current list of supported versions.

    Example:

    # uname -r
4.18.0-425.3.1.el8.x86_64

  3. Install the nvme-cli package:

    Example:

    # rpm -qa|grep nvme-cli
nvme-cli-1.16-5.el8.x86_64

  4. Enable in-kernel NVMe multipath:

    Example

    # grubby --args=nvme_core.multipath=Y --update-kernel
/boot/vmlinuz-4.18.0-425.3.1.el8.x86_64

  5. 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:a7f7a1d4-311a-11e8-b634-            7ed30aef10b7

::> vserver nvme subsystem host show -vserver vs_nvme167
Vserver     Subsystem       Host NQN
----------- --------------- ----------------
vs_nvme167 rhel_167_LPe35002  nqn.2014-08.org.nvmexpress:uuid: a7f7a1d4-311a-11e8-b634-7ed30aef10b7
    Note 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.

  6. Reboot the host.

    Note

    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. You can do this 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

  1. 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
LPe35002-M2
LPe35002-M2
# cat /sys/class/scsi_host/host*/modeldesc
Emulex LightPulse LPe35002-M2 2-Port 32Gb Fibre Channel Adapter
Emulex LightPulse LPe35002-M2 2-Port 32Gb Fibre Channel Adapter

  2. 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
14.0.505.12, sli-4:6:d
14.0.505.12, sli-4:6:d
# cat /sys/module/lpfc/version
0:14.0.0.15

  3. Verify that lpfc_enable_fc4_type is set to 3

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

  4. 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
0x100000109b95467c
0x100000109b95467b
# cat /sys/class/fc_host/host*/port_state
Online
Online
# cat /sys/class/scsi_host/host*/nvme_info
NVME Initiator Enabled
XRI Dist lpfc1 Total 6144 IO 5894 ELS 250
NVME LPORT lpfc1 WWPN x100000109b95467c WWNN x200000109b95467c DID x0a1500 ONLINE
NVME RPORT       WWPN x2071d039ea36a105 WWNN x206ed039ea36a105 DID x0a0907 TARGET DISCSRVC ONLINE
NVME RPORT       WWPN x2072d039ea36a105 WWNN x206ed039ea36a105 DID x0a0805 TARGET DISCSRVC ONLINE

NVME Statistics
LS: Xmt 00000001c7 Cmpl 00000001c7 Abort 00000000
LS XMIT: Err 00000000  CMPL: xb 00000000 Err 00000000
Total FCP Cmpl 0000000004909837 Issue 0000000004908cfc OutIO fffffffffffff4c5
abort 0000004a noxri 00000000 nondlp 00000458 qdepth 00000000 wqerr 00000000 err 00000000
FCP CMPL: xb 00000061 Err 00017f43

NVME Initiator Enabled
XRI Dist lpfc0 Total 6144 IO 5894 ELS 250
NVME LPORT lpfc0 WWPN x100000109b95467b WWNN x200000109b95467b DID x0a1100 ONLINE
NVME RPORT       WWPN x2070d039ea36a105 WWNN x206ed039ea36a105 DID x0a1007 TARGET DISCSRVC ONLINE
NVME RPORT       WWPN x206fd039ea36a105 WWNN x206ed039ea36a105 DID x0a0c05 TARGET DISCSRVC ONLINE

NVME Statistics
LS: Xmt 00000001c7 Cmpl 00000001c7 Abort 00000000
LS XMIT: Err 00000000  CMPL: xb 00000000 Err 00000000
Total FCP Cmpl 0000000004909464 Issue 0000000004908531 OutIO fffffffffffff0cd
abort 0000004f noxri 00000000 nondlp 00000361 qdepth 00000000 wqerr 00000000 err 00000000
FCP CMPL: xb 0000006b Err 00017f99
Marvell/QLogic FC adapter for NVMe/FC

The native inbox qla2xxx driver included in the RHEL 8.7 kernel has the latest fixes. These fixes are essential for ONTAP support.

Steps

  1. Verify that you are running the supported adapter driver and firmware versions using the following command:

    # cat /sys/class/fc_host/host*/symbolic_name
QLE2772 FW:v9.08.02 DVR:v10.02.07.400-k-debug
QLE2772 FW:v9.08.02 DVR:v10.02.07.400-k-debug

  2. 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.

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

  1. Set the lpfc_sg_seg_cnt parameter to 256:

    cat /etc/modprobe.d/lpfc.conf
    options lpfc lpfc_sg_seg_cnt=256

  2. Run the dracut -f command, and reboot the host.

  3. 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

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

    # nvme discover -t tcp -w 192.168.211.5 -a 192.168.211.14

Discovery Log Number of Records 8, Generation counter 10

=====Discovery Log Entry 0======
trtype:  tcp
adrfam:  ipv4
subtype: unrecognized
treq:    not specified
portid:  0
trsvcid: 8009
subnqn:  nqn.199208.com.netapp:sn.154a5833c78c11ecb069d039ea359e4b:discovery
traddr:  192.168.211.15
sectype: none
=====Discovery Log Entry 1======
trtype:  tcp
adrfam:  ipv4
subtype: unrecognized
treq:    not specified
portid:  1
trsvcid: 8009
subnqn:  nqn.1992-08.com.netapp:sn.154a5833c78c11ecb069d039ea359e4b:discovery
traddr:  192.168.111.15
sectype: none
=====Discovery Log Entry 2======
trtype:  tcp
adrfam:  ipv4
subtype: unrecognized
treq:    not specified
portid:  2
trsvcid: 8009
subnqn:  nqn.1992-08.com.netapp:sn.154a5833c78c11ecb069d039ea359e4b:discovery
traddr:  192.168.211.14
sectype: none
=====Discovery Log Entry 3======
trtype:  tcp
adrfam:  ipv4
subtype: unrecognized
treq:    not specified
portid:  3
trsvcid: 8009
subnqn:  nqn.1992-08.com.netapp:sn.154a5833c78c11ecb069d039ea359e4b:discovery
traddr:  192.168.111.14
sectype: none
=====Discovery Log Entry 4======
trtype:  tcp
adrfam:  ipv4
subtype: nvme subsystem
treq:    not specified
portid:  0
trsvcid: 4420
subnqn:  nqn.1992-08.com.netapp:sn.154a5833c78c11ecb069d039ea359e4b:subsystem.rhel_tcp_165
traddr:  192.168.211.15
sectype: none
=====Discovery Log Entry 5======
trtype:  tcp
adrfam:  ipv4
subtype: nvme subsystem
treq:    not specified
portid:  1
trsvcid: 4420
subnqn:  nqn.1992-08.com.netapp:sn.154a5833c78c11ecb069d039ea359e4b:subsystem.rhel_tcp_165
traddr:  192.168.111.15
sectype: none
=====Discovery Log Entry 6======

trtype:  tcp
adrfam:  ipv4
subtype: nvme subsystem
treq:    not specified
portid:  2
trsvcid: 4420
subnqn:  nqn.1992-08.com.netapp:sn.154a5833c78c11ecb069d039ea359e4b:subsystem.rhel_tcp_165
traddr:  192.168.211.14
sectype: none

=====Discovery Log Entry 7======
trtype:  tcp
adrfam:  ipv4
subtype: nvme subsystem
treq:    not specified

   portid:  3

trsvcid: 4420
subnqn:  nqn.1992-08.com.netapp:sn.154a5833c78c11ecb069d039ea359e4b:subsystem.rhel_tcp_165
traddr:  192.168.111.14
sectype: none
[root@R650-13-79 ~]#

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

    # nvme discover -t tcp -w 192.168.211.5 -a 192.168.211.14
# nvme discover -t tcp -w 192.168.211.5 -a 192.168.211.15
# nvme discover -t tcp -w 192.168.111.5 -a 192.168.111.14
# nvme discover -t tcp -w 192.168.111.5 -a 192.168.111.15

  3. 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 192.168.211.5-a 192.168.211.14 -l 1800
# nvme connect-all -t tcp -w 192.168.211.5 -a 192.168.211.15 -l 1800
# nvme connect-all -t tcp -w 192.168.111.5 -a 192.168.111.14 -l 1800
# nvme connect-all -t tcp -w 192.168.111.5 -a 192.168.111.15 -l 1800

Validate NVMe-oF

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

Steps

  1. Verify that in-kernel NVMe multipath is indeed enabled by checking:

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

  2. 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

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

    # nvme list
Node           SN                    Model                   Namespace
------------   --------------------- ---------------------------------
/dev/nvme0n1   81Gx7NSiKSRNAAAAAAAB   NetApp ONTAP Controller   1

Usage                Format         FW Rev
-------------------  -----------    --------
21.47  GB /  21.47  GB  4 KiB + 0 B    FFFFFFFF

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

    # nvme list-subsys /dev/nvme1n1

nvme-subsys0 - NQN=nqn.1992-08.com.netapp:sn.154a5833c78c11ecb069d039ea359e4b:subsystem.rhel_tcp_165

\

 +- nvme0 tcp traddr=192.168.211.15 trsvcid=4420 host_traddr=192.168.211.5 live non-optimized

 +- nvme1 tcp traddr=192.168.211.14 trsvcid=4420 host_traddr=192.168.211.5 live optimized

 +- nvme2 tcp traddr=192.168.111.15 trsvcid=4420 host_traddr=192.168.111.5 live non-optimized

 +- nvme3 tcp traddr=192.168.111.14 trsvcid=4420 host_traddr=192.168.111.5 live optimized

  5. 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_tcp79     /vol/vol1/ns1 

NSID  UUID                                   Size
----  ------------------------------         ------
1     79c2c569-b7fa-42d5-b870-d9d6d7e5fa84  21.47GB


# nvme netapp ontapdevices -o json
{

  "ONTAPdevices" : [
  {

      "Device" : "/dev/nvme0n1",
      "Vserver" : "vs_tcp79",
      "Namespace_Path" : "/vol/vol1/ns1",
      "NSID" : 1,
      "UUID" : "79c2c569-b7fa-42d5-b870-d9d6d7e5fa84",
      "Size" : "21.47GB",
      "LBA_Data_Size" : 4096,
      "Namespace_Size" : 5242880
    },

]

}

Known issues

The NVMe-oF host configuration for RHEL 8.7 with ONTAP has the following known issues:

NetApp Bug ID Title Description

1479047

RHEL 8.7 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) 8.7 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.