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SAN hosts and cloud clients

Use SUSE Linux Enterprise Server 12 SP3 with ONTAP

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You can use the ONTAP SAN host configuration settings to configure SUSE Linux Enterprise Server 12 SP3 with ONTAP as the target.

Install the Linux Unified Host Utilities

The NetApp Linux Unified Host Utilities software package is available on the NetApp Support Site in a 32-bit and 64-bit .rpm file. If you don't know which file is right for your configuration, use the NetApp Interoperability Matrix Tool to verify which one you need.

NetApp strongly recommends installing the Linux Unified Host Utilities, but it's not mandatory. The utilities don't change any settings on your Linux host. The utilities improve management and assist NetApp customer support in gathering information about your configuration.

If you have Linux Unified Host Utilities currently installed, you should either upgrade it to the latest version, or remove it and follow these steps to install the latest version.

Steps

  1. Download the 32-bit or 64-bit Linux Unified Host Utilities software package from the NetApp Support Site to your host.

  2. Install the software package:

    rpm -ivh netapp_linux_unified_host_utilities-7-1.x86_64

Note You can use the configuration settings provided in this document to configure cloud clients connected to Cloud Volumes ONTAP and Amazon FSx for ONTAP.

SAN Toolkit

The toolkit is installed automatically when you install the NetApp Host Utilities package. This kit provides the sanlun utility, which helps you manage LUNs and HBAs. The sanlun command returns information about the LUNs mapped to your host, multipathing, and information necessary to create initiator groups.

Example

In the following example, the sanlun lun show command returns LUN information.

# sanlun lun show all

Example output:

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

SAN Booting

What you'll need

If you decide to use SAN booting, it must be supported by your configuration. You can use the NetApp Interoperability Matrix Tool to verify that your OS, HBA, HBA firmware and the HBA boot BIOS, and ONTAP version are supported.

Steps

  1. Map the SAN boot LUN to the host.

  2. Verify that multiple paths are available.

    Note Multiple paths become available after the host operating system is up and running on the paths.

  3. Enable SAN booting in the server BIOS for the ports to which the SAN boot LUN is mapped.

    For information on how to enable the HBA BIOS, see your vendor-specific documentation.

  4. Reboot the host to verify that the boot was successful.

Multipathing

For SUSE Linux Enterprise Server 12 SP3 the /etc/multipath.conf file must exist, but you do not need to make specific changes to the file. SUSE Linux Enterprise Server 12 SP3 is compiled with all settings required to recognize and correctly manage ONTAP LUNs.

You can use the multipath -ll command to verify the settings for your ONTAP LUNs.

The following sections provide example multipath outputs for a LUN mapped to ASA and non-ASA personas.

All SAN Array configurations

All SAN Array (ASA) configurations optimize all paths to a given LUN, keeping them active. This improves performance by serving I/O operations through all paths at the same time.

Example

The following example displays the correct output for an ONTAP LUN.

# multipath -ll
3600a0980383034466b2b4a3775474859 dm-3 NETAPP,LUN C-Mode
size=20G features='4 queue_if_no_path pg_init_retries 50 retain_attached_hw_handle' hwhandler='1 alua' wp=rw
|-+- policy='round-robin 0' prio=50 status=active
| |- 1:0:8:1  sdb 8:16 active ready running
| `- 2:0:8:1  sdd 8:48 active ready running
`-+- policy='round-robin 0' prio=10 status=enabled
  |- 1:0:9:1  sdc 8:32 active ready running
  `- 2:0:9:1  sde 8:64 active ready running
Note A single LUN shouldn't require more than four paths. Having more than four paths might cause path issues during storage failures.

Non-ASA configurations

For non-ASA configurations, there should be two groups of paths with different priorities. The paths with higher priorities are Active/Optimized, meaning they are serviced by the controller where the aggregate is located. The paths with lower priorities are active but are non-optimized because they are served from a different controller. The non-optimized paths are only used when optimized paths are not available.

Example

The following example displays the correct output for an ONTAP LUN with two Active/Optimized paths and two Active/Non-Optimized paths.

# multipath -ll
3600a09803831347657244e527766394e dm-5 NETAPP,LUN C-Mode
size=80G features='4 queue_if_no_path pg_init_retries 50 retain_attached_hw_handler' 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
Note A single LUN shouldn't require more than four paths. Having more than four paths might cause path issues during storage failures.

SUSE Linux Enterprise Server 12 SP3 OS is compiled to recognize ONTAP LUNs and automatically set all configuration parameters correctly.
The multipath.conf file must exist for the multipath daemon to start. If this file doesn't exist, you can create an empty, zero-byte file by using the touch /etc/multipath.conf command.

The first time you create the multipath.conf file, you might need to enable and start the multipath services by using the following commands:

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

You don't need to add anything directly to the multipath.conf file unless you have devices that you don't want multipath to manage or you have existing settings that override defaults. To exclude unwanted devices, add the following syntax to the multipath.conf file, replacing <DevId> with the worldwide identifier (WWID) string of the device you want to exclude:

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

The following example determines the WWID of a device and adds it to the multipath.conf file.

Steps

  1. Determine the WWID:

    /lib/udev/scsi_id -gud /dev/sda
    3600a098038314c4a433f5774717a3046
/lib/udev/scsi_id -gud /dev/sda

    360030057024d0730239134810c0cb833

+
`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]
+

blacklist {
wwid 3600a098038314c4a433f5774717a3046
devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st)"
devnode "^hd[a-z]"
devnode "^cciss."
}

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 | "2 pg_init_retries 50"
| flush_on_last_del | "yes"
| hardware_handler | "0"
| no_path_retry | queue
| 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 `no_path_retry` 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.

defaults {
path_checker readsector0
no_path_retry fail
}
devices {
device {
vendor "NETAPP "
product "LUN.*"
no_path_retry queue
path_checker tur
}
}

== Known issues

The SUSE Linux Enterprise Server 15 SP3 with ONTAP release has the following known issues:

[cols=3*,options="header"]
|===
| NetApp Bug ID
| Title
| Description
| link:https://mysupport.netapp.com/NOW/cgi-bin/bol?Type=Detail&Display=1089555[1089555^] | Kernel disruption observed on kernel version SLES12 SP3 with Emulex LPe16002 16GB FC during storage failover operation | A kernel disruption might occur during storage failover operations on kernel version SLES12 SP3 with Emulex LPe16002 HBA. The kernel disruption prompts a reboot of the operating system, which in turn causes an application disruption. If the kdump is configured, the kernel disruption generates a vmcore file under /var/crash/directory. You can investigate the cause of the failure in the vmcore file.
Example:
In the observed case, the kernel disruption was observed in the module “lpfc_sli_ringtxcmpl_put+51” and is logged in the vmcore file
– exception RIP: lpfc_sli_ringtxcmpl_put+51.

Recover the operating system after the kernel disruption by rebooting the host operating system and restarting the application.
| link:https://mysupport.netapp.com/NOW/cgi-bin/bol?Type=Detail&Display=1089561[1089561^] | Kernel disruption observed on kernel version SLES12 SP3 with Emulex LPe32002 32GB FC during storage failover operations | A kernel disruption might occur during storage failover operations on kernel version SLES12 SP3 with Emulex LPe32002 HBA. The kernel disruption prompts a reboot of the operating system, which in turn causes an application disruption. If the kdump is configured, the kernel disruption generates a vmcore file under /var/crash/directory. You can investigate the cause of the failure in the vmcore file.
Example:
In the observed case, the kernel disruption was observed in the module
“lpfc_sli_free_hbq+76” and is logged in the vmcore file
– exception RIP: lpfc_sli_free_hbq+76.

Recover the operating system after the kernel disruption by rebooting the host operating system and restarting the application.
| link:https://mysupport.netapp.com/NOW/cgi-bin/bol?Type=Detail&Display=1117248[1117248^] | Kernel disruption observed on SLES12SP3 with QLogic QLE2562 8GB FC during storage failover operations |  During storage failover operations on the Sles12sp3 kernel (kernel-default-4.4.82-6.3.1) with QLogic QLE2562 HBA, the kernel disruption was observed due to a panic in the kernel. The kernel panic leads to a reboot of the operating system, causing an application disruption. The kernel panic generates the vmcore file under the /var/crash/ directory if kdump is configured. Upon the kernel panic, the vmcore file can be used to understand the cause of the failure.
Example:
In this case, the panic was observed in the “blk_finish_request+289” module.
It is logged in the vmcore file with the following string:
"exception RIP: blk_finish_request+289"

After the kernel disruption, you can recover the operating system  by rebooting the Host OS. You can restart the application as required.
| link:https://mysupport.netapp.com/NOW/cgi-bin/bol?Type=Detail&Display=1117261[1117261^] | Kernel disruption observed on SLES12SP3 with Qlogic QLE2662 16GB FC during storage failover operations | During storage failover operations on Sles12sp3 kernel (kernel-default-4.4.82-6.3.1) with Qlogic QLE2662 HBA, you might observe kernel disruption. This prompts a reboot of the operating system causing application disruption. The kernel disruption generates a vmcore file under /var/crash/ directory if kdump is configured. The vmcore file can be used to understand the cause of the failure.
Example:
In this case the Kernel disruption was observed in the module "unknown or invalid address" and is logged in vmcore file with the following string - exception RIP: unknown or invalid address.

After kernel disruption, the operating system can be recovered by rebooting the host operating system and restarting the application as required.
| link:https://mysupport.netapp.com/NOW/cgi-bin/bol?Type=Detail&Display=1117274[1117274^] | Kernel disruption observed on SLES12SP3 with Emulex LPe16002 16GB FC during storage failover operations | During storage failover operations on Sles12sp3 kernel (kernel-default-4.4.87-3.1) with Emulex LPe16002 HBA, you might observe kernel disruption. This prompts a reboot of the operating system causing application disruption. The kernel disruption
generates a vmcore file under the /var/crash/ directory if kdump is configured. The vmcore file can be used to understand the cause
of the failure.
Example:
In this case kernel disruption was observed in the module “raw_spin_lock_irqsave+30” and is logged in the vmcore file with the following string:
– exception RIP: _raw_spin_lock_irqsave+30.

After kernel disruption, the operating system can be recovered by rebooting the host operating system and restarting the application as required.
|===

// 2024 SEP 2, ONTAPDOC-2345