Infrastructure Software

Hello,

I read the following in the Oracle Linux 5.7 release notes:
http://oss.oracle.com/el5/docs/RELEASE-NOTES-U7-en.html

For the Unbreakable Enterprise Kernel, the default IO scheduler is the 'deadline' scheduler.
For the Red Hat Compatible Kernel, the default IO scheduler is the 'cfq' scheduler.

I read about the various Linux I/O schedulers at http://www.linuxjournal.com/article/6931?page=0,2. Then I found the following the information at http://www.redhat.com/magazine/008jun05/features/schedulers/ which also compares the different schedulers, showing that the "CFQ" scheduler is faster than the "Deadline" scheduler. The "Noop" scheduler seems to be the best option with intelligent I/O controllers. According to the summary, there is no single answer to which I/O scheduler is best.

Q: Are there guidelines to choose which I/O scheduler is the best to use. For instance, I remember that the "noop" scheduler is the best I/O scheduler option for SSD drives. Is there a short explanation why the scheduler was changed from "cfg" to "deadline" in 5.7?

Thanks.

I upgraded form 5.6 to 5.7 using public yum.

/etc/grub.conf shows elevator=noop for vmlinuz-2.6.32-200.13.1.el5uek

Isn't this supposed to be "deadline" according to the release notes? Btw, I'm using Virtualbox. Maybe the installation of the guest additions put in the "noop" and the update took it over?

Edited by: Dude on Aug 5, 2011 5:03 AM