Fibre Channel Protocol

If the Operating System being used for SAP HANA is SLES for SAP Applications 12 SP4 or later, or RHEL for SAP Applications 8 or later, it is

recommended to use the "none" io scheduler.

To enable none as an IO scheduler in SLES follow the below steps:

1. Edit the /etc/default/grub file and add "scsi_mod.use_blk_mq=1 dm_mod.use_blk_mq=y " to GRUB_CMDLINE_LINUX_DEFAULT
   1. GRUB_CMDLINE_LINUX_DEFAULT="splash=silent resume=/dev/disk/by-path/pci-0000:03:00.0-scsi-0:0:0:0-part2 quiet crashkernel=199M,high crashkernel=72M,low scsi_mod.use_blk_mq=1 dm_mod.use_blk_mq=y"
2. Run the grub2-mkconfig command to ensure the new bootloader options are applied on the next reboot.
   1. grub2-mkconfig -o /boot/grub2/grub.cfg
3. Reboot the system.

   To enable non as an IO scheduler in RHEL follow the below steps:

4. Edit the /etc/default/grub file and add "scsi_mod.use_blk_mq=1 dm_mod.use_blk_mq=y " to GRUB_CMDLINE_LINUX_DEFAULT
   1. GRUB_CMDLINE_LINUX_DEFAULT="splash=silent resume=/dev/disk/by-path/pci-0000:03:00.0-scsi-0:0:0:0-part2 quiet crashkernel=199M,high crashkernel=72M,low scsi_mod.use_blk_mq=1 dm_mod.use_blk_mq=y"
5. Run the grub2-mkconfig command to ensure the new bootloader options are applied on the next reboot.
   1. grub2-mkconfig -o /boot/efi/EFI/redhat/grub.cfg
6. Reboot the system.

To check the "none" scheduler is available for each device look at the scheduler property:

cat /sys/block/sda/queue/scheduler
[none] mq-deadline kyber bf

If using none as an IO scheduler ensure the /etc/udev/rules.d/99-pureudev configuration file is updated to apply the correct setting for each device:

ACTION=="add|change", KERNEL=="sd*[!0-9]", SUBSYSTEM=="block", ENV{ID_VENDOR}=="PURE", ATTR{queue/scheduler}="none"
ACTION=="add|change", KERNEL=="dm*[!0-9]", SUBSYSTEM=="block", ENV{ID_VENDOR}=="PURE", ATTR{queue/scheduler}="none"