Once the IO scheduler elevator has been set to 'noop' it is often desired to keep the setting persistent, after reboots.
Step 1: Create the Rules File
Create a new file in the following location. The OS will use the udev rules to set the elevators after each reboot.
/etc/udev/rules.d/99-pure-storage.rules
Step 2: Add the Following Entries to the Rules File
The following entries automatically sets the elevator to 'noop' each time the system is rebooted. Create a file that has the following entries, ensuring each entry exists on one line with no carriage returns:
# Recommended settings for Pure Storage FlashArray.
# Use noop scheduler for high-performance solid-state storage
ACTION=="add|change", KERNEL=="sd*[!0-9]", SUBSYSTEM=="block", ENV{ID_VENDOR}=="PURE", ATTR{queue/scheduler}="noop"
# Reduce CPU overhead due to entropy collection
ACTION=="add|change", KERNEL=="sd*[!0-9]", SUBSYSTEM=="block", ENV{ID_VENDOR}=="PURE", ATTR{queue/add_random}="0"
# Spread CPU load by redirecting completions to originating CPU
ACTION=="add|change", KERNEL=="sd*[!0-9]", SUBSYSTEM=="block", ENV{ID_VENDOR}=="PURE", ATTR{queue/rq_affinity}="2"
# Set the HBA timeout to 60 seconds
ACTION=="add", SUBSYSTEMS=="scsi", ATTRS{model}=="FlashArray ", RUN+="/bin/sh -c 'echo 60 > /sys/$DEVPATH/device/timeout'"Note:
Please note that 6 spaces are needed after "FlashArray" under "Set the HBA timeout to 60 seconds" above for the rule to take effect.
Reference