# sanlun lun show all

controller(7mode/E-Series)/            device     host               lun
vserver(cDOT/FlashRay)   lun-pathname  filename   adapter  protocol  size    Product
------------------------------------------------------------------------------------
data_vserver          /vol/vol1/lun1   /dev/sdb   host16   FCP       120.0g  cDOT
data_vserver          /vol/vol1/lun1   /dev/sdc   host15   FCP       120.0g  cDOT
data_vserver          /vol/vol2/lun2   /dev/sdd   host16   FCP       120.0g  cDOT
data_vserver          /vol/vol2/lun2   /dev/sde   host15   FCP       120.0g  cDOT

# multipath -ll
3600a09803831347657244e527766394e dm-5 NETAPP,LUN C-Mode
size=80G features='4 queue_if_no_path pg_init_retries 50 retain_attached_hw_handle' hwhandler='1 alua' wp=rw
|-+- policy='service-time 0' prio=50 status=active
| |- 11:0:1:0 sdj 8:144 active ready running
| |- 11:0:2:0 sdr 65:16 active ready running
|-+- policy='service-time 0' prio=10 status=enabled
|- 11:0:0:0 sdb 8:i6 active ready running
|- 12:0:0:0 sdz 65:144 active ready running

chkconfig multipathd on
/etc/init.d/multipathd start

blacklist {
        wwid <DevId>
        devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st)[0-9]*"
        devnode "^hd[a-z]"
        devnode "^cciss.*"
}

+
`sda` is the local SCSI disk that you want to add to the blacklist.

. Add the `WWID` to the blacklist stanza in `/etc/multipath.conf`:
[source,cli]
+

Always check your `/etc/multipath.conf` file, especially in the defaults section, for legacy settings that might be overriding default settings.

The following table demonstrates the critical `multipathd` parameters for ONTAP LUNs and the required values. If a host is connected to LUNs from other vendors and any of these parameters are overridden, they must be corrected by later stanzas in the `multipath.conf` file that apply specifically to ONTAP LUNs. Without this correction, the ONTAP LUNs might not work as expected. You should only override these defaults in consultation with NetApp, the OS vendor, or both, and only when the impact is fully understood.

//ONTAPDOC-2578 9-Dec-2024
//ONTAPDOC-2561 25-Nov-202


[cols=2*,options="header"]
|===
| Parameter
| Setting
| detect_prio | yes
| dev_loss_tmo | "infinity"
| failback | immediate
| fast_io_fail_tmo | 5
| features | "3 queue_if_no_path pg_init_retries 50"
| flush_on_last_del | "yes"
| hardware_handler | "0"
| path_checker | "tur"
| path_grouping_policy | "group_by_prio"
| path_selector | "service-time 0"
| polling_interval | 5
| prio | "ontap"
| product | LUN.*
| retain_attached_hw_handler | yes
| rr_weight | "uniform"
| user_friendly_names | no
| vendor | NETAPP
|===

.Example

The following example shows how to correct an overridden default. In this case, the `multipath.conf` file defines values for `path_checker` and `detect_prio` that are not compatible with ONTAP LUNs. If they cannot be removed because of other SAN arrays still attached to the host, these parameters can be corrected specifically for ONTAP LUNs with a device stanza.

NOTE: To configure Oracle Linux 7.6 Red Hat Enterprise Kernel (RHCK), use the link:hu_rhel_76.html#recommended-settings[recommended settings] for Red Hat Enterprise Linux (RHEL) 7.6.

== Known issues

The Oracle Linux 7.6 with ONTAP release has the following known issues:

[cols=3*,options="header"]
|===
| NetApp Bug ID
| Title
| Description
| 1440718 | If you unmap or map a LUN without performing a SCSI rescan, it might lead to data corruption on the host. | When you set the 'disable_changed_wwids' multipath configuration parameter to YES, it disables access to the path device in the event of a WWID change. Multipath will disable access to the path device until the WWID of the path is restored to the WWID of the multipath device. To learn more, see  link:https://kb.netapp.com/Advice_and_Troubleshooting/Flash_Storage/AFF_Series/The_filesystem_corruption_on_iSCSI_LUN_on_the_Oracle_Linux_7[NetApp Knowledge Base: The filesystem corruption on iSCSI LUN on the Oracle Linux 7^].
| link:https://mysupport.netapp.com/NOW/cgi-bin/bol?Type=Detail&Display=1202736[1202736^] | LUNs might not be available during host discovery due to "Not Present" state of remote ports on a OL7U6 host with QLogic QLE2742 adapter |During host discovery, the status of Fibre Channel (FC) remote ports on a OL7U6 host with a QLogic QLE2742 adapter might enter into "Not Present" state. Remote ports with a "Not Present" state might cause paths to LUNs to become unavailable. During storage failover, the path redundancy might be reduced and result in an I/O outage.
You can check the remote port status by entering the following command:
# cat /sys/class/fc_remote_ports/rport-*/port_state
The following is an example of the output that is displayed:
  Online
  Online
  Not Present
  Online
  Online
| link:https://mysupport.netapp.com/NOW/cgi-bin/bol?Type=Detail&Display=1204078[1204078^] | Kernel disruption occurs on Oracle Linux 7.6 running with Qlogic(QLE2672) 16GB FC HBA during storage failover operations | During storage failover operations on the Oracle Linux 7.6 with a Qlogic QLE2672 Fibre Channel (FC) host bus adapter (HBA), a kernel disruption occurs due to a panic in the kernel. The kernel panic causes Oracle Linux 7.6 to reboot, which leads to an application disruption.   If the kdump mechanism is enabled, the kernel panic generates a vmcore file located in the /var/crash/ directory. You can analyze the vmcore file to determine the cause of the panic.  After the kernel disruption, you can reboot the host OS and recover the operating system, and then you can restart any applications as required.
| link:https://mysupport.netapp.com/NOW/cgi-bin/bol?Type=Detail&Display=1204351[1204351^] | Kernel disruption might occur on Oracle Linux 7.6 running with Qlogic(QLE2742) 32GB FC HBA during storage failover operations | During storage failover operations on the Oracle Linux 7.6 with a Qlogic QLE2742 Fibre Channel (FC) host bus adapter (HBA), a kernel disruption might occur due to a panic in the kernel. The kernel panic causes Oracle Linux 7.6 to reboot, which leads to an application disruption. If the kdump mechanism is enabled, the kernel panic generates a vmcore file located in the /var/crash/ directory. You can analyze the vmcore file to determine the cause of the panic.
After the kernel disruption, you can reboot the host OS and recover the operating system, and then you can restart any applications as required.
| link:https://mysupport.netapp.com/NOW/cgi-bin/bol?Type=Detail&Display=1204352[1204352^] | Kernel disruption might occur on Oracle Linux 7.6 running with Emulex (LPe32002-M2)32GB FC HBA during storage failover operations | During storage failover operations on the Oracle Linux 7.6 with an Emulex LPe32002-M2 Fibre Channel (FC) host bus adapter (HBA), a kernel disruption might occur due to a panic in the kernel. The kernel panic causes Oracle Linux 7.6 to reboot, which leads to an application disruption.
 If the kdump mechanism is enabled, the kernel panic generates a vmcore file located in the /var/crash/ directory. You can analyze the vmcore file to determine the cause of the panic.
After the kernel disruption, you can reboot the host OS and recover the operating system, and then you can restart any applications as required.
| link:https://mysupport.netapp.com/NOW/cgi-bin/bol?Type=Detail&Display=1246134[11246134^] | No I/O progress on Oracle Linux 7.6 with UEK5U2 kernel, running with an Emulex LPe16002B-M6 16G FC HBA during storage failover operations | During storage failover operations on the Oracle Linux 7.6 with the UEK5U2 kernel running with an Emulex LPe16002B-M6 16G Fibre Channel (FC) host bus adapter (HBA), I/O progress might stop due to reports getting blocked. The storage failover operation reports change from an "online" state to a "blocked" state, causing a delay in read and write operations. After the operation has completed successfully, the reports fail to move back to an "online" state and continue to remain in a "blocked" state.
| link:https://mysupport.netapp.com/NOW/cgi-bin/bol?Type=Detail&Display=1246327[1246327^] | Remote port status on QLogic QLE2672 16G host blocked during storage failover operations | Fibre Channel (FC) remote ports might be blocked on Red Hat Enterprise Linux (RHEL) 7.6 with the QLogic QLE2672 16G host during storage failover operations. Because the logical interfaces go down when a storage node is down, the remote ports set the storage node status to blocked. IO progress might stop due to the blocked ports if you are running both a QLogic QLE2672 16G host and a QLE2742 32GB Fibre Channel (FC) host bus adapter (HBA).
When the storage node returns to its optimal state, the logical interfaces also come up and the remote ports should be online. However, the remote ports might still be blocked. This blocked state registers as failed faulty to LUNS at the multipath layer. You can verify the state of the remote ports with the following command:
 # cat /sys/class/fc_remote_ports/rport-*/port_stat
 You should see the following output:
 Blocked
 Blocked
 Blocked
 Blocked
 Online
 Online
|===

// 2024 SEP 2, ONTAPDOC-2345
// BURT 1440718, 2022-05-20