Linux and Unix tutorials for new and seasoned sysadmin
Linux and Unix tutorials for new and seasoned sysadmin
I’m not able to boot into GUI under Dell desktop system, which uses an ATI HD3750 display card. The display only works with CLI and but when I type startx and get some sort of error or a black screen. How do I fix this issue?
Q. How do I fix the following error under CentOS Enterprise Linux:
LVM error VG meta data inconsistent
How do I fix this error?
Q. I’m using CentOS Linux 5 server with ext3 on /disk2 (/dev/sdb1). How do I improve my file server performance. I’ve many large files in directories and how do I speed up access time?
Continue reading “Linux Optimize Directories ( File Access Time ) in ext3 Filesystem”
Q. Can I run fsck or e2fsck command when Linux file system is mounted? Do you advice to run fsck on a live file system? I am using Cent OS.
A. No. Do not run fsck on a live or mounted file system. fsck is used to check and optionally repair one or more Linux file systems. Running fsck on a mounted filesystem can usually result in disk / data corruption. So please do not do it. You have two choices
(a) Take down system to single user mode and unmout system
(b) Boot from the installation CD into rescue mode
Following are steps :
=> Use init (process control initialization ) command to change runlevel 1 (singe user mode)
=> Use umount command to unmount /home file system
=> Run fsck using fsck command
Let us say you would like to run fsck on /home (/dev/sda3):
# init 1
# umount /home
# umount /dev/sda
# fsck /homeOR
# fsck /dev/sda3OR
# e2fsck -y /dev/sda3
If you are using Cent OS/Fedora Core/RHEL linux, boot from first CD and at boot prompt type linux rescue nomount:
boot: linux rescue nomount
Now make new node for disk and partition 3:
# mknod /dev/sda
# mknod /dev/sda3
# fsck /dev/sda3
OR
# e2fsck -y /dev/sda3
Don’t forget to reboot the system:
# exit;exit
# reboot
Q. I forgot my root password, how can I get into my system?
A. You can reset forgotten root password under Linux by booting system into single user mode or emergency mode (also known as rescue mode).
)Following is the procedure to reset root password if you are using GRUB as a boot loader:
You need to mount at least / and other partitions:
# mount -t proc proc /proc
# mount -o remount,rw /
Change the root password, enter:
# passwd
Finally reboot system:
# sync
# reboot
At LILO boot loader type linux single and press [ENTER] key:
Boot: linux single
When you get the # prompt you will need to type passwd root to reset password:
# passwd
Reboot system:
# sync
# reboot
Q. How do I boot a Linux system into single user mode?
