CentOS

CentOS 5.8

1) Release date 7 march 2012.
2) end of life 31 march 2017 .
3) new pakages .
binutils220
iotop
mysql-connector-odbc64
pixman
postgresql-odbc64
python-ctypes
spice-client
spice-protocol
virt-who
unixODBC64
4)possible to upgrade 5.11  throught yum update .

--->but before that need to take backup of important data .
a) backup /etc directory .
b) backup important logs /var/log .
c) back webserver configution file .
d) dump database .

CentOS 5.11

1)30 September 2014 .

2)end of life 31 march 2017 .

3)new pakages .

gcc-libraries

mysql51

mysql51-mysql

mysql55

mysql55-mysql

        python-dateutil

        python-kerberos

        python-lxml

php53-odbc64

libitm

scl-utils

ant17

java-1.7.0-openjdk

rsyslog5

hypervkvpd  

CentOS 6.6

1) Release Date  November 15, 2014  .

2)end od life 30-Nov-20.

3) Major changes .

a)Enhanced SCSI unit attention handling to enable responding to certain unit commands.

b)The OpenvSwitch module is now available as a kernel module.

c)New HyperV daemons have been added to enable/improve running  CentOS in Microsoft HyperV hosts.

d)As a technology preview 6.6 can be run as a 2nd generation VM on  Microsoft's 2012R2 HyperV.

e)keepalived and haproxy are now fully supported.

f)Support added for the Intel Wildcat platform.

g)OpenJDK 8 has been added as technology preview. 

3)possible to upgrade 6.7 throught yum update .

--->but before that need to take backup of important data .

a) backup /etc directory .

b) backup important logs /var/log .

c) back webserver configution file .

d) dump database . 

CentOS 6.7

1) Release Date  November 15, 2014  .

2)end od life 30-Nov-20.

3) Major changes .

a)Enhanced SCSI unit attention handling to enable responding to certain unit commands.

b)The OpenvSwitch module is now available as a kernel module.

c)New HyperV daemons have been added to enable/improve running  CentOS in Microsoft HyperV hosts.

d)As a technology preview 6.6 can be run as a 2nd generation VM on  Microsoft's 2012R2 HyperV.

e)keepalived and haproxy are now fully supported.

f)Support added for the Intel Wildcat platform.

g)OpenJDK 8 has been added as technology preview. 

3)possible to upgrade 6.7 throught yum update .

--->but before that need to take backup of important data .

a) backup /etc directory .

b) backup important logs /var/log .

c) back webserver configution file .

d) dump database . 

not possible to upgrade ( CentOS 5.8 , CentOS 5.11)  to ( CentOS 6.6 , CentOS 6.7) .

some reason I am Mentioning below .

1) (CentOS 5.8 , CentOS 5.11) have  ext3 file system and (CentOS 6.6 , CentOS 6.7) have ext4 file system through yum update file system cannot upgrade . 

2)  Insufficient Hardware. new operating system requires fresh hardware but upgrading OS new virsion that run very slowly .

3)  Setup Error and Freezes . probabaly the worst case scenario is when the setup process fails in the middle of an upgrade this can leave you stuck in computer purgatory with neither the old operating system nor new usable .

  

4)  this can be also caused by hardware issue .

5)  driver problem .

6)  Application incompatabilities .

7)  performance problem .

8) permission acess problem .

9) interface proble . 

Fresh installation is always good as compaire to upgrede .

    

But there is way to upgrade .

1) take and test full backup off old system .

2) install CentOS 6.7 in new Machine .

3) look Old macine backup file /etc/*rpm* .

4)Find out the application from old data .

Mejor Difference of CentOS 5.11 and CenOS 6.7 .

1) Virtualization: In CentOS 6.7 KVM (Kernel based Virtual Machine) was used as a hypervisor but in the earlier releases of CentOS XEN was used as a hypervisor. The main advantage of KVM is that it supports the installation of many virtual machines/operating systems like Windows, Linux, Solaris and also it is very easy to manage those virtual machines.

2)Security: CentOS 6.7 has an enhanced version of SELinux(Security Enhanced Linux) now, Basically now the features are more improved and there are various new set of rules which are added to SELinux one of such rule/feature is of SVirt which provides security to virtual machines from hackers.

    EXT4: It stands for Extended 4, It has various new advantages then EXT2/3 which were used in earlier version(s) of RHEL. EXT4 is comparatively more faster and easy to manage then previous file systems.

    IPv6: CentOS 6.7 supports IPv6.

    NFS4: It uses NFSv4 (Network File Transfer) the latest version of NFS for the sharing of files in the network rather than NFSv3.

    GUI: It has a far better GUI(Graphical User Interface) then CentOS 5.11 or any of its prior version.