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:
- SCSI INQUIRY TIMEOUT
- SCSI COMMAND TIMEOUT
- Multipath settings in multipath.conf
-
Add scsi_mod.inq_timeout=70 to the kernel boot command line through GRUB configuration. By adding the scsi_mod.inq_timeout=70 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 and SLES15 servers, follow these steps:- To make the permanent change, edit
/etc/default/grub
and add to theGRUB_CMDLINE_LINUX_DEFAULT
line:scsi_mod.inq_timeout=70
- Run the following command to rewrite the boot
record:
grub2-mkconfig -o /boot/grub2/grub.cfg
- To make the permanent change, edit
-
For RHEL6, RHEL7 and RHEL8 servers, follow these steps:
- To make the change permanent, edit
/etc/sysconfig/grub
and add to the GRUB_CMDLINE_LINUX line:scsi_mod.inq_timeout=70
- Run the following command to rewrite the boot
record:
grub2-mkconfig -o /etc/grub2.cfg
The previous steps will be effective after rebooting. In RHEL6, RHEL7, RHEL8, SLES12, and SLES15, 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. .
Use the following command to change the inq_timeout parameter temporarily without rebooting:echo 70 > /sys/module/scsi_mod/parameters/inq_timeout
In RHEL6, RHEL7, RHEL8, SLES12, and SLES15 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 70:Module = "scsi_mod"
inq_timeout = "70"
- To make the change permanent, edit
- Set the udev rules for SCSI command timeout to 120s. This is the recommended setting for all versions of Linux.
- To increase the SCSI command timeout for the system, create the following udev rule:
# Set SCSI command timeout to 120s (default == 30 or 60) for IBM 2145 devices SUBSYSTEM=="block", ACTION=="change", ENV{ID_VENDOR}=="IBM",ENV{ID_MODEL}=="2145", RUN+="/bin/sh -c 'echo 120 >/sys/block/%k/device/timeout'"
- After you set up your volumes, confirm that they are set for 120 seconds. Locate the block device paths by running multipath -ll | grep sd from the command prompt. Then, run cat /sys/block/sdX/device/timeout (where X is each 2145 block device path).
- To reload the udev rules without rebooting (or dynamically) you can run the following commands:
udevadm control -R /sbin/udevadm trigger --type=devices --action=add