Attachment requirements for hosts that are running the Linux operating system

Ensure that your system meets the requirements for attaching to a host that is running the Linux operating system.

The following list provides the requirements for attaching the system to the host that is running the Linux operating system:

Check the LUN limitations for your host system.
Do not remove LUN 0, as access to other mapped LUNs might be affected.
Ensure that you have the documentation for your host and access to the hardware installation information for the correct model of your system. All system publications are available from the following website:
https://datacentersupport.lenovo.com/
Ensure that you install the correct operating systems and are running a supported kernel of Linux.
When you attach the system to a BladeCenter blade server, see the BladeCenter documentation for SAN configuration details.
All RHEL7 and SLES12 systems require that you set the scsi_mod.inq_timeout parameter to 30 seconds. Otherwise, RHEL7 and SLES12 hosts cannot regain previously failed paths such as in a system update or where a node is manually rebooted.
To resolve this issue, add scsi_mod.inq_timeout=30 to the kernel boot command line through grub configuration. By adding the scsi_mod.inq_timeout=30 parameter, the change in the parameter is persistent from a server reboot. Linux hosts can also regain system node paths when lost. This change can be done by completing the following steps.
For SLES12 servers, follow these steps:
1. To make the change permanent, edit /etc/default/grub and add to the GRUB_CMDLINE_LINUX_DEFAULT line:
```
scsi_mod.inq_timeout=30
```
2. Run the following command to rewrite the boot record:
```
#'grub2-mkconfig -o /boot/grub2/grub.cfg
```
For RHEL7 servers, follow these steps:
1. To make the change permanent, edit /etc/sysconfig/grub and add to the GRUB_CMDINE_LINUX line:
```
scsi_mod.inq_timeout=30
```
2. Run the following command to rewrite the boot record:
```
# grub2-mkconfig -o /etc/grub2.cfg
```
The previous steps will not take into effect until after a reboot. However, you can decide to make the change take effect without the reboot if you are unable to reboot the server. In both RHEL7 and SLES12, you can choose to change the inq_timeout parameter temporarily without rebooting. This method will not keep the parameter value persistent if the system ever reboots in the future and if you do not edit the grub configuration by following these steps. It is best to do both tasks in case the server is rebooted in the future.
Use the following command to change the inq_timeout parameter temporarily without rebooting:
Note: If the server is rebooted, the default value is not reset.
```
# echo 30 > /sys/module/scsi_mod/parameters/inq_timeout
```
In either RHEL7 or SLES12, enter the following command to view that the change was made:
```
# systool -m scsi_mod -A inq_timeout
```
The output of the command shows that the value is changed to 30:
```
Module = "scsi_mod"
```
```
inq_timeout         = "30"
```