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grub.conf

HowTo: Turn off SELinux

How do I turn off SELinux (Security-Enhanced Linux) under Linux operating systems?
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Linux Disable USB Devices (Disable loading of USB Storage Driver)

In our research lab, would like to disable all USB devices connected to our HP Red Hat Linux based workstations. I would like to disable USB flash or hard drives, which users can use with physical access to a system to quickly copy sensitive data from it. How do I disable USB device support under CentOS Linux, RHEL version 5.x/6.x/7.x and Fedora latest version?
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Linux: Skip or Bypass a Fsck

Q. I know how to force fsck on the next reboot using /forcefsck file. But how do I skip or bypass a fsck on reboot? How to stop a FSCK from prompting or running automatically when rebooting server.
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Q. My CDROM drive attached to Stratus ftServer 6210 is not working and it is dumping me with following error:

hdb: lost interrupt
hdb: lost interrupt

hdb: lost interrupt
hdb: status error: status=0x59 { DriverReady SeekComplete DataRequest
Error }
hdb: status error: status=0x40 { LastFailedSense=0x04 }
ide: failed opcode was: unknown
hdb: drive not ready for command
hdb: lost interrupt
hdb: status error: status=0x59 { DriverReady SeekComplete DataRequest
Error }
hdb: status error: status=0x40 { LastFailedSense=0x04 }

How do I fix this error under Linux?
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Linux kernel: Uhhuh. NMI received for unknown reason 30

Q. I’ve upgrade my CentOS / RHEL (Red Hat Enterprise Linux) 4.7 on HP ProLiant DL580 G5 and it is showing unknown NMI errors in the logs:

Uhhuh. NMI received for unknown reason 30.
Dazed and confused, but trying to continue
Do you have a strange power saving mode enabled?

Uhhuh. NMI received for unknown reason 20.
Dazed and confused, but trying to continue
Do you have a strange power saving mode enabled?

How do I fix this error?
A. This is caused when the system is hanging under load. Add any one of the following to you /boot/grub.conf file:

  1. Disable the NMI watchdog by adding “nmi_watchdog=0
  2. Disable the high precision event timer (HPET) by adding “nohpet

Open grub.conf, type:
vi grub.conf
Make modification to kernel line as follows:

title Red Hat Enterprise Linux AS (2.6.9-78.0.8.EL)
        root (hd0,0)
        kernel /vmlinuz-2.6.9-78.0.8.EL ro nohpet root=/dev/VolGroup00/LogVol00 nohpet
        initrd /initrd-2.6.9-78.0.8.EL.img

Save and close the file. Reboot the server:
# reboot