Performance Tuning for Linux Software Raid

After finishing my Homeserver project I wanted to get the maximum of performance. At the end of my research in the web i have created following script:

# Get Arrays and physical Disks for active Raid5 Volumes

ARRAYS=""
DISKS=""

for field in `cat /proc/mdstat | grep "active raid5"`
do
  if [[ "x${field:0:2}x" == "xmdx" ]]
  then
    ARRAYS="$ARRAYS $field"
  elif [[ "x${field:0:2}x" == "xsdx" ]]
  then
    DISKS="$DISKS ${field:0:3}"
  fi
done

# Changes on physical Devices
for disk in $DISKS
do
  #Set read-ahead to 16MB
  blockdev --setra 16384 /dev/$disk
  #Device Queue Tuning
  echo 1024 > /sys/block/$disk/queue/read_ahead_kb
  echo 256 > /sys/block/$disk/queue/nr_requests
  #Disable NCQ
  echo 1 > /sys/block/$disk/device/queue_depth
done

# Changes on Raid Arrays
for array in $ARRAYS
do
  #Set read-ahead to 64MB
  blockdev --setra 64536 /dev/$array
  #Increase stripe-cache size
  echo 16384 > /sys/block/$array/md/stripe_cache_size
done

This are the optimal and tested settings for my system. The numbers can differ from system to system. You have to test.

Alexander Worlitschek

IT Enthusiast with focus on linux, vmware, container technologies