run RedHat AS4 on VMWare ESX 3

[Aleksandar Milivojevic]

zhicheng wang wrote:

> please does any one have experience on running redhat
> AS4 on VMWare virtual machines? We are in the process
> of upgrading servers and one option is vitalisation.

RHEL4 runs on VMware virtual machines, with some gotchas.

VMware can emulate either lsilogic or buslogic SCSI controller.  RHEL4
supports only lsilogic, so you'll have to configure virtual machines
with lsilogic (VMware provides device driver for buslogic controller,
but there's no point installing it, since lsilogic works just fine).

There are some clock issues with virtual machines that run 2.6 version
of Linux kernel.  These are mainly due to change of kernel's internal HZ
constant from 100 (pre-2.6 kernels) to 1000 (2.6 kernel).  You can
either recompile 2.6 kernel with HZ set to 100, or you can use one of
the available workarounds (using clock=pit kernel option when booting
and VMware-tools for clock synchronization between host and guest OS --
note that you'll need both).  Note that if you have too many virtual
machines running 2.6 kernel with HZ set to 1000 on single host, you
might experience high CPU usage of the host even when all those machines
are idle.  There was a discussion about this issues on Nahant (RHEL4)
mailing list, you might want to check the thread Kernel timer for 2.6
kernel in the mailing list archives.