Editing Different kernel flavors (UP, SMP, ENTERPRISE, ENTNOSPLIT)

OpenVZ project releases several different precompiled kernels for each version. Which kernel to choose depends on what hardware you have. The table below describes the cases when it is better to use each of these kernels.

== RHEL6-based kernels ==

RHEL6 kernels come in single flavor only which is SMP and PAE (for 32bit) enabled. This is because nowadays it's hard to find single core CPUs and less then 4GB RAM machines.
{{Note|RHEL6 kernels no longer support enterprise versions of 32bit kernels with 4/4GB split, which limits 32bit version.}}

== RHEL5-based kernels ==

{| class="wikitable"
|+'''i686 kernel flavors list'''
! Kernel type !! Description !! Hardware !! Use case
|-
! i686 UP
| uniprocessor
| up to 4GB of RAM
|
|-
! i686 SMP
| symmetric multiprocessor
| up to 4 GB of RAM
| 10-20 [[Container]]s
|-
! i686 entnosplit/PAE
| SMP + PAE support
| up to 64 GB of RAM
| 10-30 [[Container]]s
|-
! i686 enterprise/ent
| SMP + PAE support + 4/4GB split
| up to 64 GB of RAM
| >20 [[Container]]s
|}


These kernels are optimized for these types of hardware configurations and usage scenarios,
so choosing the right kernel can help to boost performance by about 5 to 15 per cent.

{{Note|Use <tt>rpm -ihv</tt> command for ovzkernel RPM installation. Please do not use the <tt>rpm -Uhv</tt> command to install the kernel, otherwise all the previously installed kernels may be removed from your system.}}

{{Note|When using a <b>64-bit</b> processor <b>and</b> operating system, you need only select the SMP or non-SMP version. With the Redhat repos this will be ''ovzkernel.x86_64''. 64-bit linux can access the entire RAM in ZONE_NORMAL (low memory).  PAE and 4GB/4GB splitting is only needed for 32-bit OS, and so are not necessary and are disabled by default in 64-bit kernels.}}

New RHEL5 based kernel uses different flavors naming: 
* '''UP''' kernel is no longer provided 
* '''SMP''' kernel comes without any flavor (like old UP)
* '''entnosplit''' kernel comes as '''PAE '''
* '''enterprise''' kernel comes as '''ent'''
* '''ovzkernel.x86_64''' for 64-bit

[[Category: Kernel]]
[[Category: Installation]]