Raid Stands for Redundant Array of Independent Disks.It is 
a set of Technology standards for Teamingup DiskDrives to 
improve Performence and FaultTolerance. Totally there are 6 
levels in Raid
0 - stripping
1 - Mirroring
2 - Stripping and Mirroring
3 - Onfficially Not Defined
4 - Striping with Differential Parity
5 - Striping with Distributional Parity

Raid stands for redundant array of inexpensive disk. there
are two types of raid : software raid and hardware raid.
most of mnc used hdd raid. this is the techonolgy used for
faulttorance and increase perfomance!
there software available raid are raid 0, 1 ,2,3,4,5,6
in which 5 is most used.

redundant array of inexpensive disk, this is used for data
distribution and data redundancy.
levels
0 data distributed (no redundancy)
1 data distributed across disk and having a mirror of each
disk, its expensive
5 data distributed with parity

Raid is Redundant Array of Independent Disks/Device.It is 
Technology to improve Disk read & write Performence and 
FaultTolerance., By adding new disk u can recover data if 
one of disk goes down / fails. parity is a calculated 
technique to rebuild data from disk fails.
levels in Raid
0 - stripping
1 - Mirroring
3 - Striping with Parity
5 - Striping with Parity with more fault tolerant widley 
used.

Kernel panic error occurs when a Linux OS files may missing

kernel panic acured when linux kernel can not communicat 
with any hardware or any OS related file.

(1)Suppose any problem in initrd file then kernel panic
error showing
(2)Any file system problem or any change or remove file system 
then showing the kernel panic error

this error is just due to prblem in grub.conf and or system
is unable to root filesystem. if the prob is due ti
grub.conf go in resue mode and open grub.conf which reside
in /boot/grub/grub.conf  and make the entry given below!

default=0
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title Red Hat Enterprise Linux Server (2.6.18-53.el5)
        root (hd0,0)
        kernel /vmlinuz-<version> ro root=<root mount drive
ie. /dev/hda2> rhgb quiet
        initrd /initrd-<version.img>
you can check your root mount drive by e2label utility!
#e2label /dev/sdan  , where n is the no of ur partition.

kernel panic error occurs when the system cannot boot the
machine due to some fatal errors, it might be with the
hardware or software.

A kernel panic is an action taken by an operating system 
upon detecting an internal fatal error from which it cannot 
safely recover. Attempts by the operating system to read an 
invalid or non-permitted memory address are a common source 
of kernel panics. A panic may also occur as a result of a 
hardware failure or a bug in the operating system.

majority ther problem is with the grub.conf file and the
fstab file.
when grub.conf is corrupt it will not be able to find the 
1) kernel loader (vmlinuz.2.6....
2) inital ram disk (initrd.2.6......img
OR .. it will not able to read the /boot directory
incase grub is correct and fstab entry is wrong in / section
or /boot section it will give the error

Edit /etc/samba/smb.conf

add the folder details to be shared ,permissions,users ...

any user is ftp user.

Adding the user to the ftp group will allow to use FTP, for 
security reasons anonymous users must be disable

firstly create the user.
useradd surendra
passwd surendra

then opne the FTP file:-
vi /etc/vsftpd/vsftpd.conf
add this line at the end of the file
userlist_deny=NO

then open this file,
vi /etc/vsftpd/user_list

and add the above created user in this file to access FTP
services.

and restart the FTP services
/etc/init.d/vsftpd start
chkconfig vsftpd on  ( for permanent on )

When create the user by default it is ftp user and he can
login in ftp.

Cups is nothing but service for printer.It can be 
configured by editing vi /etc/cups.conf file
after editing the file we need to start the cups service

it is service for printer
The command is system-config-printer

cups stand for comman unix printer service. It is a daemon 
used to install printer in linux . we can configure printer 
either by setup command or by sytem-config-printer in 
terminal windows.

Cups is mainly use for printing. It is mainly use for recive
print job and inform print service. Cups is stand for common
unix printing system. 
To configure cups:
# system-config-printer

"dump" utility is used to take backup.

cpio,tar,dump is used to take backups

cpio with find command ,tar with gun/bunzip ,dump with only 
ext2 & ext3 Fs used to take backups 
Also you have amanda software in RHEL 4.0 version to take a 
backup

Simple configuration
--------------------
Install apache: (get the rpm for apache)

# rpm -ivh httpd.rpm

# vi /etc/httpd/conf/httpd.conf

and change 
ServerName your-domain.com

Start apache : service httpd start

Verify by pointing the browser to http://localhost/

I am using RHEL5

 TO configure apache simple install httpd rpm
   if you have yum then run
    yum install httpd

   & service httpd restart

   these two commands will start your apache server

   to check start browser & browse to your hostname

Hi,

You just need to install yum install httpd
after that in this fine you have to edit
vi /etc/httpd/conf/httpd.conf

At the last just copy the 7 line
and paste it
it will ask for virtual host it should be yr ip adddress
like 192.168.1.141

virtual host 192.168.1.141
server admin root@station1.example.com
server name  station1.example.com
document root /var/www/html
directory index index.html
<virtual host>
  
And then check the yr configuration fine
the command is httpd -t
and restart the apache server
service httpd restart
chkconfig httpd on

The sudo command stands for "superuser do". If a server
needs to be administered by a number of people it is
normally not a good idea for them all to use the root
account. This is because it becomes difficult to determine
exactly who did what, when and where if everyone logs in
with the same credentials. The sudo utility was designed to
overcome this difficulty.

The sudo utility allows users defined in the /etc/sudoers
configuration file to have temporary access to run commands
they would not normally be able to due to file permission
restrictions. The commands can be run as user "root" or as
any other user defined in the /etc/sudoers configuration file.

The privileged command you want to run must first begin with
the word sudo followed by the command's regular syntax. When
running the command with the sudo prefix, you will be
prompted for your regular password before it is executed.
You may run other privileged commands using sudo within a
five-minute period without being re-prompted for a password.
All commands run as sudo are logged in the log file
/var/log/messages. 

In order to use sudo we first need to configure the sudoers
file.

Do not edit directly the file:

To edit it, use the command

# visudo

******Output***************

# /etc/sudoers
#
# This file MUST be edited with the 'visudo' command as root.
#
# See the man page for details on how to write a sudoers file.
#

Defaults        env_reset

# Host alias specification

# User alias specification

# Cmnd alias specification

# User privilege specification
root    ALL=(ALL) ALL
**********************************************

You will see the line

root ALL=(ALL) ALL

This lines means that the user root can execute from ALL
terminals, acting as ALL (any) users, and run ALL (any) command.
The first part is the user, the second is the terminal from
where the user can use sudo, the third is as which user he
may act, and the last one, is which commands he may run.

Example:

Granting Access To Specific Users To Specific Files 
---------------------------------------------------
amsin21, %operator ALL= /sbin/, /usr/sbin,
/usr/local/apps/check.pl

This entry allows user amsin21 and all the members of the
group operator to gain access to all the program files in
the /sbin and /usr/sbin directories, plus the privilege of
running the command /usr/local/apps/check.pl. Notice how the
trailing slash (/) is required to specify a directory location: 

Granting Access to Specific Files as Another User 
-------------------------------------------------
The sudo -u entry allows allows you to execute a command as
if you were another user, but first you have to be granted
this privilege in the sudoers file.

This feature can be convenient for programmers who sometimes
need to kill processes related to projects they are working
on. For example, programmer amsin21 is on the team
developing a financial package that runs a program called
monthend as user accounts. From time to time the application
fails, requiring "amsin21" to stop it with the /bin/kill,
/usr/bin/kill or /usr/bin/pkill commands but only as user
"accounts". The sudoers entry would look like this:

amsin21 ALL=(accounts) /bin/kill, /usr/bin/kill, /usr/bin/pkill

User amsin21 is allowed to stop the monthend process with
this command:

# sudo -u accounts pkill monthend

Granting Access Without Needing Passwords
-----------------------------------------

This example allows all users in the group operator to
execute all the commands in the /sbin directory without the
need for entering a password. This has the added advantage
of being more convenient to the user:

%operator ALL= NOPASSWD: /sbin/

Using Aliases in the sudoers File 
---------------------------------

Sometimes you'll need to assign random groupings of users
from various departments very similar sets of privileges.
The sudoers file allows users to be grouped according to
function with the group and then being assigned a nickname
or alias which is used throughout the rest of the file.
Groupings of commands can also be assigned aliases too.

In the next example, users amsin21, amsin211 and amsin212
and all the users in the operator group are made part of the
user alias ADMINS. All the command shell programs are then
assigned to the command alias SHELLS. Users ADMINS are then
denied the option of running any SHELLS commands and su:

Cmnd_Alias    SHELLS = /usr/bin/sh,  /usr/bin/csh, \
                       /usr/bin/ksh, /usr/local/bin/tcsh, \
                       /usr/bin/rsh, /usr/local/bin/zsh
 
 
User_Alias    ADMINS = amsin21, amsin211, amsin212, %operator
ADMINS        ALL    = !/usr/bin/su, !SHELLS

This attempts to ensure that users don't permanently su to
become root, or enter command shells that bypass sudo's
command logging. It doesn't prevent them from copying the
files to other locations to be run. The advantage of this is
that it helps to create an audit trail, but the restrictions
can be enforced only as part of the company's overall
security policy.

sudo is command in linux.

sudoers user can access the root access and also can reset
the password of root account.

useradd surendra
passwd surendra

then type,
visudo   or    vi /etc/sudoers

add following entry,

surendra ALL=(ALL)      NOPASSWD:ALL

SUDO is super user domain. a domain in which we can simply 
give root powers to unpriviledge user act as an root.but 
not fully.
vi /etc/sudoers
eg.
#Host alias specification

# User alias specification

# Cmnd alias specification

# User privilege specification
root    ALL=(ALL) ALL

Iptables is the userspace command line program used to
configure the Linux 2.4.x and 2.6.x IPv4 packet filtering
ruleset. Iptables allows administrators to configure the
operating system so that it allows applications and clients
to connect through the network and stop unwanted
applications and clients from communicating and corrupting
the operating system.
It is not specific to Redhat. It is available in all linux
2.4.x and 2.6.x kernels.

Iptable is packet filtering strong firewall in linux os.

Iptable is filtering tool, check point, can create natting 
(Source nat & destination nat), Inbound, Outbound Security, 
Able block & allow port forwording, block or open a port, 
block & allow service for specific domain & for 
user,Maintain firewall security as well.

Samba provides file and print services to all manner of
SMB/CIFS clients, including the numerous versions of
Microsoft Windows operating systems. Samba configuration
file is smb.conf:

Sample smb.conf
---------------

[global]
        # Domain name ..
        workgroup = DOMAIN.NAME
        # Server name - as seen by Windows PCs ..
        netbios name = SERVER1
        # Be a PDC ..
        domain logons = Yes
        domain master = Yes
        # Be a WINS server ..
        wins support = true

        # allow user privileges
        #enable privileges = yes

        obey pam restrictions = Yes
        dns proxy = No
        os level = 35
        log file = /var/log/samba/log.%m
        max log size = 1000
        syslog = 0
        panic action = /usr/share/samba/panic-action %d
        pam password change = Yes

        # Allows users on WinXP PCs to change their password
when they press Ctrl-Alt-Del
        unix password sync = no
        ldap passwd sync = yes

        # Printing from PCs will go via CUPS ..
        load printers = yes
        printing = cups
        printcap name = cups

        # Use LDAP for Samba user accounts and groups ..
        passdb backend = ldapsam:ldap://localhost

        # This must match init.ldif ..
        ldap suffix = dc=domain,dc=name
        # The password for cn=admin MUST be stored in
/etc/samba/secrets.tdb
        # This is done by running 'sudo smbpasswd -w'.
        ldap admin dn = cn=admin,dc=domain,dc=name

        # 4 OUs that Samba uses when creating user accounts,
computer accounts, etc.
        # (Because we are using smbldap-tools, call them
'Users', 'Computers', etc.)
        ldap machine suffix = ou=Computers
        ldap user suffix = ou=Users
        ldap idmap suffix = ou=Idmap
        # Samba and LDAP server are on the same server in
this example.
        ldap ssl = no

        # Scripts for Samba to use if it creates users,
groups, etc.
        add user script = /usr/sbin/smbldap-useradd -m '%u'
        delete user script = /usr/sbin/smbldap-userdel %u
        add group script = /usr/sbin/smbldap-groupadd -p '%g'
        delete group script = /usr/sbin/smbldap-groupdel '%g'
        add user to group script =
/usr/sbin/smbldap-groupmod -m '%u' '%g'
        delete user from group script =
/usr/sbin/smbldap-groupmod -x '%u' '%g'
        set primary group script = /usr/sbin/smbldap-usermod
-g '%g' '%u'

        # Script that Samba users when a PC joins the domain ..
        # (when changing 'Computer Properties' on the PC)

        #add machine script = /usr/sbin/smbldap-useradd -w '%u'
        add machine script = /usr/sbin/useradd -s /bin/false
-d /home/nobody %u


        # Values used when a new user is created ..
        # (Note: '%L' does not work properly with
smbldap-tools 0.9.4-1)
        logon drive = H:
        logon home = \\server\%U
        logon path = \\server\Profiles\%U
        logon script = logon.bat

        # This is required for Windows XP client ..
        server signing = auto
        server schannel = Auto

[homes]
        comment = Home Directories
        path = /home/users/%U
        valid users = %S
        read only = No
        browseable = No
[netlogon]
        comment = Network Logon Service
        path = /var/lib/samba/netlogon
        admin users = root
        guest ok = Yes
        browseable = No

[Profiles]
        comment = Roaming Profile Share
        # would probably change this to elsewhere in a
production system ..
        path = /var/lib/samba/profiles
        read only = No
        profile acls = Yes
        browsable = No
        hide files = /desktop.ini/ntuser.ini/NTUSER.*/

[printers]
        comment = All Printers
        path = /var/spool/samba
        use client driver = Yes
        create mask = 0600
        guest ok = Yes
        printable = Yes
        browseable = No
        public = yes
        writable = yes
        admin users = root
        write list = root

[print$]
        comment = Printer Drivers Share
        path = /var/lib/samba/printers
        write list = root
        create mask = 0664
        directory mask = 0775
        admin users = root

Test it with :

# testparm /etc/samba/smb.conf

Load smb config files from /etc/samba/smb.conf
Processing section "[homes]"
Processing section "[netlogon]"
Processing section "[Profiles]"
Processing section "[printers]"
Processing section "[print$]"
Loaded services file OK.
Server role: ROLE_DOMAIN_PDC
Press enter to see a dump of your service definitions

A nice writeup :

hxxp://thegoldenear.org/toolbox/unices/samba-3-pdc-print-server-debian-etch.html

basically SAMBA is use to share the files between linux to
windows. 


firstly installed the require rpm for samba,
like this :-- yum install samba -y
              yum install samba-swat -y

then open samba file under /etc dir,
vi /etc/samba/smb.conf
and enter your share path,valid user.
Ex.  comment = windows sharing
     path = path/your/share/directory
     valid users = surendra
     writable = yes
     browseable = yes


then type testparm for code testing.

then give the password to smb users :-
smbpasswd -a surendra

and finally restart the service of samba:-

/etc/init.d/smb start
chkconfig smb on    ( for permanent on)

samba is samba.its build with 5 characters.those are:-
1>>S
2>>A
3>>M
4>>B
5>>A
can you believe the samba is build 5 character but its
true.This is technology.

configuration file of samba:-
--------------------------------
vi computer/folder/samba file
and it will work without any trabel.its good one.
thanks and hope all of you got it....

The Network Information Service (NIS) provides a simple
network lookup service consisting of databases and processes. 

A good howto: 
hxxp://www.debian-administration.org/articles/36

NIS is a service that provides any user on that network 
with the same working environment irrespective of the 
system on that network which has been used for login 
purpose.
For example if NIS server is set up in a single system and 
configured to hold user accounts and their passwords and 
access information. Then any user on that network can login 
to his/her account that is set up in the NIS server from 
any system (with nis client running) on that configured 
network. This gives a look and feel that the user is logged 
into his/her own system. But actually its the account on 
the NIS server that is mounted on the local sytem on user 
login .

nis stands for network information service is used for 
sharing the files across the network nis is used to share 
the files in network its used in linux machines only

the configuration file of nis is vi /etc/exports

first create a folder ex: mkdir /sales
than open configuration file than write
ex: /sales 192.168.1.0/255.255.255.0(rw,sync)
that means share the file across the network than save and 
exit . if u want to see the file is shared or not command 
is showmount -e server ip address to acess the shared files 
in client machine first create a dir ex: /sales
than mount the server shared dir the command is mount 
192.168.1.0:/sales /sales
permanently mounting open configuration file vi /etc/fstab
than write /sales /sales nfs default 0 0 than save and exit

answer 3 for nfs server

NIS is a service that provides any user on that network 
with the same working environment irrespective of the 
system on that network which has been used for login 
purpose.
For example if NIS server is set up in a single system and 
configured to hold user accounts and their passwords and 
access information. Then any user on that network can login 
to his/her account that is set up in the NIS server from 
any system (with nis client running) on that configured 
network. This gives a look and feel that the user is logged 
into his/her own system. But actually its the account on 
the NIS server that is mounted on the local sytem on user 
login .

NIS is used for mapping between host name and IP address 
for a wide range of information. The clients that get 
mapped information from the server consists of user 
database and authentication information across a network.

to add to the above answer

  install sendmail-cf rpm

  after installing it

  just run service sendmail restart after any changes to 
sendmail.mc

Sendmail should be installed by default when you install Red
Hat Linux. If it is not then you need to install the
Sendmail RPM's with the Red Hat distribution.

Configuring Sendmail
--------------------

1) Edit file "/etc/mail/sendmail.mc" - Look for the line:

    DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')

Change this line to:

    dnl DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')

Save the file.

2)Make the sendmail configuration file:

# m4 /etc/mail/sendmail.mc > /etc/sendmail.cf

3)Restart Sendmail:

# /etc/rc.d/init.d/sendmail restart

above answer is true but one last step is missing 
#sendmail -d0 < /dev/null
#service sendmail restart
#chkconfig sendmail on

RHEL server comes with vsftpd which is the Very Secure File
Transfer Protocol (FTP) daemon. The server can be launched
via a xinetd or as standalone mode, in which case vsftpd
itself will listen on the network port 21.

Install vsftpd:
# yum install vsftpd

Turn on vsftpd ftp service:
# service vsftpd start

Open FTP port:
Open /etc/sysconfig/iptables file, enter:
# vi /etc/sysconfig/iptables

Append following line to open ftp port 21 before REJECT line:
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp
--dport 21 -j ACCEPT

Save and close the file. Restart the firewall:
# service iptables start

Test ftp server:

# ftp localhost

The default configuration file is /etc/vsftpd/vsftpd.conf file. 
# vi /etc/vsftpd/vsftpd.conf

firstly create the user.
useradd surendra
passwd surendra

then opne the FTP file:-
vi /etc/vsftpd/vsftpd.conf
add this line at the end of the file
userlist_deny=NO

then open this file,
vi /etc/vsftpd/user_list

and add the above created user in this file to access FTP
services.

and restart the FTP services
/etc/init.d/vsftpd start
chkconfig vsftpd on  ( for permanent on )

fisrt install yum server after then 
# yum install vsftpd*
# service vsftpd restart
# chkconfig vsftpd on
   then after for chk
# ftp <server IP>
# anonumous 

press two times enter because anonymous is using without 
password if its successfully done means ur ftp is working

Need to know the grub error code for suggesting the resolutions.

Errors Reported by the Stage 1
------------------------------
The general way that the Stage 1 handles errors is to print
an error string and then halt. Pressing Ctrl-Alt-Del will
reboot.

The following is a comprehensive list of error messages for
the Stage 1:

* "Hard Disk Error"

This error message will occur if the Stage 2 or Stage 1.5 is
being read from a hard disk, and the attempt to determine
the size and geometry of the hard disk fails.

* "Floppy Error"

This error message will occur if the Stage 2 or Stage 1.5 is
being read from a floppy disk, and the attempt to determine
the size and geometry of the floppy disk fails. It's listed
as a different error since the probe sequence is different
than for hard disks.

* "Read Error"

This error message will occur if a disk read error happens
while trying to read the Stage 2 or Stage 1.5.

* "Geom Error"

This error message will occur if the location of the Stage 2
or Stage 1.5 is not in the area supported by reading the
disk with the BIOS directly. This could occur because the
BIOS translated geometry has been changed by the user or the
disk is moved to another machine or controller after
installation, or GRUB was not installed using itself (if it
was, the Stage 2 version of this error would have been seen
during that process and it would not have completed the
install).

Errors Reported by the Stage 1.5
--------------------------------

The general way that the Stage 1.5 handles errors is to
print an error number in the form "Error: " and then halt.
Pressing Ctrl-Alt-Del will reboot.

The error numbers correspond to the Errors Reported by the
Stage 2 in the listed sequence.

Errors Reported by the Stage 2
------------------------------

The general way that the Stage 2 handles errors is to abort
the operation in question, print an error string, then (if
possible) either continue based on the fact that an error
occurred or wait for the user to deal with the error.

The following is a comprehensive list of error messages for
the Stage 2 (error numbers for the Stage 1.5 are listed
before the colon in each description):

1) "Selected item won't fit into memory"

This error is returned if a kernel, module, or raw file load
command is either trying to load it's data such that it
won't fit into memory or it is simply too big.

2) "Selected disk doesn't exist"

This error is returned if the device part of a device- or
full filename refers to a disk or BIOS device that is not
present or not recognized by the BIOS in the system.

3) "Disk read error"

This error is returned if there is a disk read error when
trying to probe or read data from a particular disk.

4) "Disk write error"

This error is returned if there is a disk write error when
trying to write to a particular disk. This would generally
only occur during an install of set active partition command.

5) "Disk geometry error"

This error is returned when a read is attempted at a linear
block address beyond the end of the BIOS translated area.
This generally happens if your disk is larger than the BIOS
can handle (512MB for (E)IDE disks on older machines or
larger than 8GB in general).

6) "Attempt to access block outside partition"

This error is returned if a linear block address is outside
of the disk partition. This generally happens because of a
corrupt filesystem on the disk or a bug in the code handling
it in GRUB (it's a great debugging tool).

7) "Partition table invalid or corrupt"

This error is returned if the sanity checks on the integrity
of the partition table fail. This is a bad sign.

8) "No such partition"

This error is returned if a partition is requested in the
device part of a device- or full filename which isn't on the
selected disk.

9) "Bad filename (must be absolute pathname or blocklist)"

This error is returned if a filename is requested which
doesn't fit the syntax/rules listed in the Filesystem
Description.

10) "Bad file or directory type"

This error is returned if a file requested is not a regular
file, but something like a symbolic link, directory, or FIFO.

11) "File not found"

This error is returned if the specified filename cannot be
found, but everything else (like the disk/partition info) is OK.

12) "Cannot mount selected partition"

This error is returned if the partition requested exists,
but the filesystem type cannot be recognized by GRUB.

13) "Inconsistent filesystem structure"

This error is returned by the filesystem code to denote an
internal error caused by the sanity checks of the filesystem
structure on disk not matching what it expects. This is
usually caused by a corrupt filesystem or bugs in the code
handling it in GRUB.

14) "Filesystem compatibility error, can\'t read whole file"

Some of the filesystem reading code in GRUB has limits on
the length of the files it can read. This error is returned
when the user runs into such a limit.

15) "Error while parsing number"

This error is returned if GRUB was expecting to read a
number and encountered bad data.

16) "Device string unrecognizable"

This error is returned if a device string was expected, and
the string encountered didn't fit the syntax/rules listed in
the Filesystem Description.

17) "Invalid device requested"

This error is returned if a device string is recognizable
but does not fall under the other device errors.

18) "Invalid or unsupported executable format"

This error is returned if the kernel image boing loaded is
not recognized as Multiboot or one of the supported native
formats (Linux zImage or bzImage, FreeBSD, or NetBSD).

19) "Loading below 1MB is not supported"

This error is returned if the lowest address in a kernel is
below the 1MB boundary. The Linux zImage format is a special
case and can be handled since it has a fixed loading address
and maximum size.

20) "Unsupported Multiboot features requested"

This error is returned when the Multiboot features word in
the Multiboot header requires a feature that is not
recognized. The point of this is that the kernel requires
special handling which GRUB is likely unable to provide.

21) "Unknown boot failure"

This error is returned if the boot attempt did not succeed
for reasons which are unknown.

22) "Must load Multiboot kernel before modules"

This error is returned if the module load command is used
before loading a Multiboot kernel. It only makes sense in
this case anyway, as GRUB has no idea how to communicate the
presence of location of such modules to a
non-Multiboot-aware kernel.

23) "Must load Linux kernel before initrd"

This error is returned if the initrd command is used before
loading a Linux kernel. Similar to the above error, it only
makes sense in that case anyway.

24) "Cannot boot without kernel loaded"

This error is returned if GRUB is told to execute the boot
sequence without having a kernel to start.

25) "Unrecognized command"

This error is returned if an unrecognized command is entered
into the command-line or in a boot sequence section of a
config file and that entry is selected.

26) "Bad or incompatible header on compressed file"

This error is returned if the file header for a supposedly
compressed file is bad.

27) "Bad or corrupt data while decompressing file"

This error is returned the run-length decompression code
gets an internal error. This is usually from a corrupt file.

28) "Bad or corrupt version of stage1/stage2"

This error is returned if the install command is pointed to
incompatible or corrupt versions of the stage1 or stage2. It
can't detect corruption in general, but this is a sanity
check on the version numbers, which should be correct.

may be grub is missconfigured / corrupted, u need to 
install grub by grub-install command
Any parameter is missing or unwanted parameter is specify 
in grub.conf file
need to install kernel , initrd image..

The only difference I can think of is the administrative 
tools.
Redhat uses Redhat-config-xxxx
and Suse uses Yast. Personally I prefer Yast because it has 
more modules. However, both tools configure the same things 
and modify the same files. If you use a tool like webmin or 
Linuxconf, you won't see a bit of difference between the 
two distros.

I use the Redhat Linux 8.0 Bible as my main reference, and 
its instructions apply to the several different Linuxes I'm 
using (more or less).

As Rick said, your main interface will be Gnome or KDE and 
the only differences you'll see there is that SuSE provides 
prettier eye candy (out of the box) than Redhat.

For software update, Redhat is using up2date or Yum like
utilities
For same purpose Suse is using Yast / Yast2

Red Hat Linux  is a product of  Red Hat 
 SuSE Linux is a product of Novell 


Upto  to Version 10 suse is  using ReiserFS  as default
Filesystem.Now they changed to ext3 as default one.

Redhat is coming with ext3 or ext2(before rhel 3 )as default
file system