Arch Linux

goplexian

Member

From: Vancouver, Canada

Registered: 2010-01-27

Posts: 17

Website

Unable to set Raid5 device read_ahead_kb value with rc.local

In my rc.local I have two commands

---

echo 16384 > /sys/block/md0/md/stripe_cache_size
echo 1024 > /sys/block/md0/queue/read_ahead_kb

---

The first command works properly, but the second command does not.

cat /sys/block/md0/md/stripe_cache_size
16384
cat /sys/block/md0/queue/read_ahead_kb
128

However, I can run the command manually after my system has booted up and it works as expected

echo 1024 > /sys/block/md0/queue/read_ahead_kb

cat /sys/block/md0/queue/read_ahead_kb
1024

I think there is only one possible explanation and that is that something on my system is setting read_ahead_kb to 128 sometime after rc.local has been run during bootup.

However I never set anything to do that, so I have no idea what is doing it or how I can stop it from happening.

Does anyone have any troubleshooting suggestions for me?
I'm completely stumped.

---

Intel Core2Quad Q9550 @ 3.4 GHz, 4GB DDR2 800MHz
GeForce GTS 250 1024MB + Raid5 Storage
blog