Red Hat / Oracle Enterprise Linux I/O tuning for Oracle databases

Starting with Red Hat 4 you can choose between four I/O scheduler which have all their pros and cons versus what you run on your server:

noop
anticipatory
deadline
cfq

In Red Hat 6 the anticipatory I/O scheduler has disappeared…

There are multiple documents stating that deadline I/O scheduler is the preferred choice when running Oracle databases.
cfq scheduler is the default one on Red Hat edition while Oracle has chosen to activate deadline scheduler by default
on its Unbreakable Enterprise Kernel (uek) kernel branch. Which tend to say that it is the one to use when running Oracle databases.

You can change it, dynamically per disk device, by modifying below file:

# echo deadline > /sys/block/${ASM_DISK}/queue/scheduler

[root@server1 ~]# cat /sys/block/sda/queue/scheduler
noop anticipatory deadline [cfq]
[root@server1 ~]# echo deadline > /sys/block/sda/queue/scheduler
[root@server1 ~]# cat /sys/block/sda/queue/scheduler
noop anticipatory [deadline] cfq

http://docs.oracle.com/database/121/CWLIN/prelinux.htm#CHDCEBCD
http://blog.yannickjaquier.com/linux/red-hat-oracle-enterprise-linux-io-tuning-for-oracle-databases.html

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