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Configuring the I/O scheduler

Veritas recommends using the Linux 'deadline' I/O scheduler for database workloads. Please configure your system to boot with the 'elevator=deadline' argument to select the 'deadline' scheduler. See:

• http://www.redhat.com/f/pdf/rhel4/RHEL4WhatsNewPdf.pdf
• http://www.novell.com/products/linuxenterpriseserver/sles9_whatsnew.pdf

 To determine whether a system is using the deadline scheduler

Look for "elevator=deadline" in /proc/cmdline.

 To configure a system to use the deadline scheduler

1. Include the elevator=deadline parameter in the boot arguments of the GRUB or ELILO configuration file. The location of the appropriate configuration file depends on the system's architecture and Linux distribution. For x86_64, the configuration file is /boot/grub/menu.lst
   • For GRUB configuration files, add the elevator=deadline parameter to the kernel command. For example, change:
   • For GRUB configuration files, add the elevator=deadline parameter to the kernel command. For example, change:

     title RHEL AS 4 smp

     root (hd1,1)

     kernel /boot/vmlinuz-2.6.9-11.ELsmp ro root=/dev/sdb2

     initrd /boot/initrd-2.6.9-11.ELsmp.img

     To:

     title RHEL AS 4 smp

     root (hd1,1)

     kernel /boot/vmlinuz-2.6.9-11.ELsmp ro
     root=/dev/sdb2 \ elevator=deadline

     initrd /boot/initrd-2.6.9-11.ELsmp.img

   • A setting for the elevator parameter is always included by SUSE in its ELILO and GRUB configuration files. In this case, change the parameter from elevator=cfq to elevator=deadline.
2. Reboot the system once the appropriate file has been modified. See the operating system documentation for more information on I/O schedulers.