pm-utils execute hdparm on all drives without being asked for

jtsn · 10-26-2013, 02:24 PM

Today I found out, why my USB hard drives behave strangely when connected to my Slackware 14.0 machines.

Seems that on every suspend/resume, pm-utils script /usr/lib/pm-utils/power.d/harddrive executes

Code:

hdparm -W 0 -S 0 -B 254 -M 0

by default on every connected drive.

While this can have unintentional consequences on USB hard drives, disabling the write cache on SATA drives causes a huge performance loss. It should never been disabled permanently, only for journal flushes, which the kernel does automatically by himself.

I solved that issue by removing the x bit on the /usr/lib/pm-utils/power.d/harddrive, but that gets overwritten by every update.

This is my opinion on this issue: If a machine has no battery and is connected to AC power all the time, such scripts should not fiddle around with any settings (including PCIe power-management and file-system read-ahead, journal commit) and should go with kernel/device defaults instead.

volkerdi · 10-26-2013, 03:32 PM

Quote:

Originally Posted by jtsn

Today I found out, why my USB hard drives behave strangely when connected to my Slackware 14.0 machines.

Seems that on every suspend/resume, pm-utils script /usr/lib/pm-utils/power.d/harddrive executes

Code:

hdparm -W 0 -S 0 -B 254 -M 0

by default on every connected drive.

While this can have unintentional consequences on USB hard drives, disabling the write cache on SATA drives causes a huge performance loss. It should never been disabled permanently, only for journal flushes, which the kernel does automatically by himself.

I solved that issue by removing the x bit on the /usr/lib/pm-utils/power.d/harddrive, but that gets overwritten by every update.

This will stop the behavior permanently:

Code:

touch /etc/pm/power.d/harddrive

Quote:

This is my opinion on this issue: If a machine has no battery and is connected to AC power all the time, such scripts should not fiddle around with any settings (including PCIe power-management and file-system read-ahead, journal commit) and should go with kernel/device defaults instead.

That's my opinion, too. I hate this sort of nonsense in the background. Thanks for pointing it out.

ill323 · 10-27-2013, 09:56 AM

I disabled the pm-utils by this:

Quote:

diff -u /etc/UPower/UPower.conf.orig /etc/UPower/UPower.conf
--- /etc/UPower/UPower.conf.orig 2012-04-09 04:57:57.000000000 +0800
+++ /etc/UPower/UPower.conf 2012-11-07 03:16:47.000000000 +0800
@@ -20,6 +20,12 @@
# default=true
AllowHibernateEncryptedSwap=true

+# This controls whether we want the powersave commands to be run when running
+# on battery or plugging AC.
+#
+# default=true
+RunPowersaveCommand=false
+
# Enable the Watts Up Pro device.
#
# The Watts Up Pro contains a generic FTDI USB device without a specific

But I'm not sure if it should be the default config.