linux - Where to put default setting from "/sys" folder in Fedora 18?

I have an SSD main disk and I want to use noop IO scheduler with it, like this:

echo noop > /sys/block/sda/queue/scheduler

But this setting gets lost after reboot. What is a right place to save this setting in Fedora 18? Or, may be, on linux in general?

Answer

The best way to do this is with a udev rule. Add a file to /etc/udev/rules.d with a rule that looks something like this:

ACTION=="add", SUBSYSTEM=="block", ENV{ID_BUS}=="scsi", ENV{ID_SERIAL}=="xxx", ATTR{queue/scheduler}="noop"

Obviously you should replace xxx with the correct serial number for the disk in question. You can find that, and other attributes you could match on, with:

udevadm info --path=/sys/block/sda --query=property

The advantage of using udev to do this, and matching on attributes like the disk serial number, is that it won't matter if it doesn't always appear at sda.