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How to change Linux Scheduler

By default Linux scheduler is set to cfq ("completely fair queuing"), how do you change it?

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  • Vertica recommends using deadline or noop. This setting can make a difference with IO-intensive operations such as data load and recovery. In the following, "sda" is the device holding the Vertica data files. Check for all data locations on each node. To see how your system is set; # cat /sys/block/sda/queue/scheduler noop deadline [cfq] The setting is the one enclosed in brackets [] . To change the setting: Stop the database as this change can cause the kernel to freeze. As the root user: # echo deadline > /sys/block/sda/queue/scheduler Then review it to confiirm that the setting was changed appropriately. # cat /sys/block/sda/queue/scheduler noop [deadline] cfq This setting only lasts until the system is rebooted, so you need to add the command to a startup script, such as those stored in /etc/init.d. More details in the Documentation: Configure the I/O Scheduler for Catalog and Data Drives: http://my.vertica.com/docs/5.1.1/HTML/index.htm#16840.htm

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