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How to disable NCQ in Fedora 21?

asked 2015-03-24 19:30:03 -0500

jwart44 gravatar image

updated 2015-03-24 21:06:52 -0500

mether gravatar image

My SATA chipset has NCQ issues (the dreaded "READ FPDMA QUEUED" error) and to mitigate them I want to disable NCQ as suggested by .

I tried both ideas given on but my dmesg output still contains

ata3.00: [...], multi 1: LBA48 NCQ (depth 31/32), AA

indicating that NCQ is on per . Additionally, /sys/block/sda/device/queue_depth defaults back to 31 on every restart, even after running

echo 1 > /sys/block/sda/device/queue_depth

How do I permanently disable NCQ in Fedora 21?

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answered 2015-04-02 15:50:45 -0500

spot gravatar image

Assuming that setting the drive queue_depth to 1 resolves your issue, you should be able to do this with the tmpfiles.d component in systemd.

Make a new .conf file in /etc/tmpfiles.d, lets call it /etc/tmpfiles.d/noncq.conf. Inside it, put this line:

w /sys/block/sda/device/queue_depth - - - - 1

man tmpfiles.d will explain that syntax in depth, but essentially, we're teling tmpfiles.d to write a 1 to that file.

When you reboot, it should take effect.

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Asked: 2015-03-24 19:30:03 -0500

Seen: 419 times

Last updated: Apr 02 '15