How to Keep Hardware Clock in Local Time

If you dual boot or multiple boot different systems (Linux/Windows), you should keep your system clock in local time meaning you want to disable UTC; otherwise, the clock will be inconsistent between different systems.

Fedora/Red Hat systems:

newemachine# vi /etc/sysconfig/clock

Change 'True' to 'False' in the line where it says 'UTC=True'

Ubuntu/Debian Systems:

newemachine# vi /etc/default/rcS

Change 'yes' to 'no' in the line where it says 'UTC=yes'

Reference

Have fun experimenting with RAID

If your kernel compiled with RAID support and your system supports RAID, the /proc/mdstat exists

[shanren@newemachines ~]$ cat /proc/mdstat Personalities : unused devices:

I have reserved two equal-sized unformatted partitions

[shanren@newemachines ~]$ egrep '(sda4|sdb3|blocks)' /proc/partitions major minor #blocks name 8 4 9052627 sda4 8 19 9052627 sdb3

Let's grab mdadm--RAID administration tool

[root@newemachines shanren]# yum -y install mdadm Loading "installonlyn" plugin Setting up Install Process Parsing package install arguments fedora 100% |=========================| 2.1 kB 00:00 Resolving Dependencies --> Running transaction check ---> Package mdadm.i386 0:2.6.2-4.fc7 set to be updated Dependencies Resolved ============================================================================= Package Arch Version Repository Size ============================================================================= Updating: mdadm i386 2.6.2-4.fc7 updates 817 k Transaction Summary ============================================================================= Install 0 Package(s) Update 1 Package(s) Remove 0 Package(s) Total download size: 817 k Downloading Packages: (1/1): mdadm-2.6.2-4.fc7. 100% |=========================| 817 kB 00:11 Running Transaction Test Finished Transaction Test Transaction Test Succeeded Running Transaction Updating : mdadm ######################### [1/2] Cleanup : mdadm ######################### [2/2] Updated: mdadm.i386 0:2.6.2-4.fc7 Complete!

I want to construct RAID 1 with two partitions on separate hard drives and format it with ext3 file system

[root@newemachines shanren]# /sbin/mdadm --create --verbose /dev/md0 --level=raid1 --raid-devices=2 /dev/sda4 /dev/sdb3 mdadm: size set to 9052544K mdadm: array /dev/md0 started. [root@newemachines shanren]# /sbin/mkfs.ext3 /dev/md0 mke2fs 1.39 (29-May-2006) Filesystem label= OS type: Linux Block size=4096 (log=2) Fragment size=4096 (log=2) 1133440 inodes, 2263136 blocks 113156 blocks (5.00%) reserved for the super user First data block=0 Maximum filesystem blocks=2319450112 70 block groups 32768 blocks per group, 32768 fragments per group 16192 inodes per group Superblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632 Writing inode tables: done Creating journal (32768 blocks): done Writing superblocks and filesystem accounting information: done This filesystem will be automatically checked every 32 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override.

Checking the status of building the RAID

[root@newemachines shanren]# cat /proc/mdstat Personalities : [raid1] md0 : active raid1 sdb3[1] sda4[0] 9052544 blocks [2/2] [UU] [==========>..........] resync = 50.0% (4530496/9052544) finish=5.0min speed=15035K/sec unused devices: [root@newemachines shanren]# cat /proc/mdstat Personalities : [raid1] md0 : active raid1 sdb3[1] sda4[0] 9052544 blocks [2/2] [UU] unused devices:

Mount the RAID

[root@newemachines shanren]# mkdir /mnt/raid [root@newemachines shanren]# mount -t ext3 -v /dev/md0 /mnt/raid /dev/md0 on /mnt/raid type ext3 (rw)

Create the configuration file for mdadm so I can assemble the created array easily later on. I use mdadm with --detail option to obtain the detailed array information and add that information to /etc/mdadm.conf. My final mdadm.conf is shown.

[root@newemachines shanren]# /sbin/mdadm --detail --scan ARRAY /dev/md0 level=raid1 num-devices=2 UUID=00c674c9:04162ff3:124ba3d9:31646810 [root@newemachines ~]# cat /etc/mdadm.conf DEVICE /dev/sda4 /dev/sdb3 ARRAY /dev/md0 level=raid1 num-devices=2 UUID=00c674c9:04162ff3:124ba3d9:31646810 devices=/dev/sda4,/dev/sdb3

Should we check how well RAID 1 perform?

[root@newemachines shanren]# ls -lh debian-testing-i386-netinst.iso |cut -d" " -f5 159M [root@newemachines shanren]# time cp debian-testing-i386-netinst.iso Desktop/ real 0m0.720s user 0m0.018s sys 0m0.629s [root@newemachines shanren]# time cp debian-testing-i386-netinst.iso /mnt/raid/ real 0m0.697s user 0m0.019s sys 0m0.613s [root@newemachines shanren]# ls -lh F-7-i386-DVD.iso |cut -d" " -f5 2.8G [root@newemachines shanren]# time cp F-7-i386-DVD.iso Desktop/ real 3m18.350s user 0m0.422s sys 0m14.498s [root@newemachines shanren]# time cp F-7-i386-DVD.iso /mnt/raid/ real 7m14.209s user 0m0.453s sys 0m13.556s

As the file size increases, the overhead of RAID 1 becomes quite noticeable.

I would like to see if RAID 1 does what it is supposed to do--Mirroring

[root@newemachines shanren]# umount /dev/md0 [root@newemachines shanren]# /sbin/mdadm --stop /dev/md0 mdadm: stopped /dev/md0 [root@newemachines shanren]# mkdir /mnt/raiddevice0 /mnt/raiddevice1 [root@newemachines ~]# mount /dev/sda4 /mnt/raiddevice0 [root@newemachines ~]# mount /dev/sdb3 /mnt/raiddevice1 [root@newemachines ~]# md5 /mnt/raiddevice0/F-7-i386-DVD.iso 355bdb01b0268a4bb7c757f2737dcf7c /mnt/raiddevice0/F-7-i386-DVD.iso [root@newemachines ~]# md5 /mnt/raiddevice1/F-7-i386-DVD.iso 355bdb01b0268a4bb7c757f2737dcf7c /mnt/raiddevice1/F-7-i386-DVD.iso

Obviously, it does because the md5 of the files written to two RAID devices is the same

Let's clean it up...

[root@newemachines ~]# umount /mnt/raiddevice0 /mnt/raiddevice1 [root@newemachines ~]# rmdir /mnt/raiddevice0 /mnt/raiddevice1 [root@newemachines shanren]# /sbin/mdadm --assemble --verbose /dev/md0 mdadm: looking for devices for /dev/md0 mdadm: /dev/sda4 is identified as a member of /dev/md0, slot 0. mdadm: /dev/sdb3 is identified as a member of /dev/md0, slot 1. mdadm: added /dev/sdb3 to /dev/md0 as 1 mdadm: added /dev/sda4 to /dev/md0 as 0 mdadm: /dev/md0 has been started with 2 drives.

Reference: Link 1, Link 2, Link 3

Quick way to find out what types of file systems you can under FreeBSD on your machine

Open a terminal and run:

ls /sbin/mount_*

The following tells the kinds of file systems I can mount under my FreeBSD such as ntfs, ext2fs(linux ext2, ext3 file systems) and etc.

newemachine# ls /sbin/mount_* /sbin/mount_cd9660 /sbin/mount_mfs /sbin/mount_procfs /sbin/mount_devfs /sbin/mount_msdosfs /sbin/mount_reiserfs /sbin/mount_ext2fs /sbin/mount_nfs /sbin/mount_std /sbin/mount_fdescfs /sbin/mount_nfs4 /sbin/mount_udf /sbin/mount_linprocfs /sbin/mount_ntfs /sbin/mount_umapfs /sbin/mount_linsysfs /sbin/mount_nullfs /sbin/mount_unionfs

Say, now I plug in a USB drive have two slices. The first slice da0s1 is a NTFS file system and the second slice da0s2 is an ext3 file system. I can mount them as follows:

newemachine# mount -t ntfs /dev/da0s1 /media newemachine# mount -t ext2fs /dev/da0s2 /mnt

How to Add Startup Programs (Linux & FreeBSD)

This applies to different desktop managers (XDM, GDM, and KDM)

newemachine$ vi ~/.xsession

then put your commands to the following in the file

#!/bin/sh gnome-terminal & exec /usr/bin/gnome-session

This runs gnome-terminal after you log into a Gnome session. You can substitute 'gnome-terminal' with other commands that you want to run. 'exec /usr/bin/gnome-session' is required here; otherwise, as soon as starting gnome-terminal process finishes, you will be taken back to the log in window. The directory of window managers such as Gnome varies from distribution to distribution. If you run a different window manager, you want to change '/usr/bin/gnome-session' accordingly.

newemachine$ chmod u+x ~/.xsession

.xsession has to be executable to get this working.

Learning FreeBSD

How to Install a FreeBSD Application

• install pre-compiled applications

newemachine# pkg_add -r bash

The above command installs precompiled Bash application.


• install ports

newemachine# cd /usr/ports/www/bash newemachine# make install clean

The above command download necessary source pre, then compile and install it.

How to find a FreeBSD Application

• Option 1: (If you know the exact application name)

newemachine# whereis xclock xclock: /usr/local/bin/xclock /usr/share/man/man1/xclock.1.gz /usr/ports/x11/xclock



• Option 2:

newemachine# cd /usr/ports newemachine# make search name=xclock Port: xclock-1.0.2 Path: /usr/ports/X11/xclock Info: Analog and digital clock for X .......

How to Give User Superuser Privilege

• allow a user to sudo

newemachine# pkg_add -r sudo newemachine# /usr/local/sbin/visudo


then add the following line after 'root ALL=(ALL) ALL'


shawn ALL=(ALL) ALL

this gives user shawn the superuser privilege


• allow a user to su

newemachine# vi /etc/group

then add change 'wheel:*:0:root' to 'wheel:*:0:root,shawn', this adds user shawn to the wheel group which have the superuser privilege.

How to Configure X

• create a X server configuration file

newemachine# Xorg -configure



• test newly created configuration file

newemachine# X -config /root/xorg.conf.new

If you see a gray screen with x mouse cursor, then X is running ok. Now Ctrl + Alt + Backspace to exit X


• fine-tune X configuration

newemachine# mv /root/xorg.conf.new /etc/X11/xorg.conf


Move tested configuration to the system-wide configuration directory

newemachine# vi /etc/X11/xorg.conf


Under Section "Screen", add a line DefaultDepth 24 after the line where it says Monitor "Monitor0"
then under SubSection "Display", add a line Modes "1024x768" (#change to your own screen resolution) after the line where it says Depth 24

newemachine# startx

start the X server!

How to Configure Sound Card

• load a set of common sound device drivers

newemachine# kldload snd_driver



• test loaded sound card driver

newemachine# cat /dev/sndstat

You will see something similar to the following:


FreeBSD Audio Driver (newpcm)
Installed devices:
pcm0:  at io 0xffa7f800, 0xffa7f400 irq 17 bufsz 16384 kld snd_ich (1p/1r/0v channels duplex default)

This means that my actual sound card driver is snd_ich; therefore, I can load snd_ich instead of snd_driver.


newemachine# kldload snd_ich



• load modules at boot

newemachine# vi /boot/loader.conf


add snd_ich_load="YES" to the file

OSes

Too many operating systems to choose from? Or you only use Windows? Read on:
--> Plain English: FreeBSD vs Linux vs Windows
--> Kernel Talk: A Comparison of Solaries, Linux, and FreeBSD Kernels

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