Racadm: Enable Read ahead on disks on a Dell RAID controller (Misc)

Category: Misc

Just occasionally, you'll be looking into performance issues and find that, for some reason, someone has disabled read-ahead when creating virtual disks in the raid controller.

Dell's documentation tells you how to modify this in such an obscure and obfuscated way that it's almost a match for HP's server documentation.

This snippet details how to change read-ahead for disks on a Dell RAID controller using racadm

Details

  • Language: Misc

Snippet

# Check whether Read-ahead is enabled
#
# Make a note of a disk's "reference", e.g. Disk.Virtual.2:RAID.Integrated.1-1
# as you'll need the second half later
racadm raid get vdisks -o -p ReadPolicy

# Enable it on the 2nd disk
racadm set Storage.VirtualDisk.ReadPolicy.2 "Read Ahead"

# Disable it on the third disk
racadm set Storage.VirtualDisk.ReadPolicy.3 "No Read Ahead"

# Make the changes active
#
# The RAID reference is the second half of the disk reference you noted earlier
racadm jobqueue create RAID.Integrated.1-1 -s TIME_NOW --realtime

Usage Example

# Assuming we have 25 vdisks, enable for all
for i in {1..25}; do racadm set Storage.VirtualDisk.ReadPolicy.$i "Read Ahead"; done
racadm jobqueue create RAID.Integrated.1-1 -s TIME_NOW --realtime

# Wait a while and then verify
racadm raid get vdisks -o -p ReadPolicy