CentOS - Jul 2011 - HOWTO install CentOS 6 on low memory computer or virtual machine (even 192MB RAM)

I've managed to install CentOS 6 on a 192MB virtual machine using LiveCD
install-to-disk graphical method.

This is not normally possible because of:
- hard-coded minimum supported memory in Anaconda installer - it will
show a message "You do not have enough RAM to install CentOS Linux on
this machine" if you try or force you to use seriously crippled text
installer;
- a bug in Anaconda installer, which prevents it from using swap during
installation.

I think it would be useful to be able to install CentOS 6 (or Scientific
Linux 6 or RedHat Enterprise Linux - RHEL 6) on low memory old computer
or laptop, as it can be very capable firewall, home www server, proxy etc.

So the procedure is as follows:

1. Boot to 32-bit CentOS LiveCD (CentOS-6.0-i386-LiveCD.iso) in
graphical mode (if you have at least 256MB RAM) or text mode (if you
have less than 256MB RAM).

2. Login as root.

3. Edit a file /usr/sbin/anaconda - using vim in text mode or gedit in
graphical mode - search for "within" and modify function
"within_available_memory" adding a line "return True" like
this:
    def within_available_memory(needed_ram):
        return True
        # kernel binary code estimate that is
        # not reported in MemTotal by /proc/meminfo
        epsilon = 15360 # 15 MB
        return needed_ram < (iutil.memInstalled() + epsilon)
This would get rid of artificial hard-coded memory requirement.

4. Edit a file /usr/lib/anaconda/storage/__init__.py - search for 4th
occurrence of "swapoff" and modify a fragment of function
"umountFilesystems" from:
    for device in devices:
        if not device.format.mountable and \
           (device.format.type != "swap" or swapoff):
           continue
to:
    for device in devices:
        if not (device.format.mountable and \
           (device.format.type != "swap" or swapoff)):
           continue
(add parentheses - left one after "if not" and right one after
"or
swapoff"). This would fix a bug in installer.

5. Run "liveinst" which should start graphical installer.

6. During installation create swap partition so that you have at least
1GB of available memory (RAM+swap) (default setup should suffice, but I
personally do not recommend it as it used LVM, which AFAIK prevents
disks from using barriers).

The bug is reported upstream:
https://bugzilla.redhat.com/show_bug.cgi?id=708966 but for Fedora Linux.

Regards
Tometzky
-- 
...although Eating Honey was a very good thing to do, there was a
moment just before you began to eat it which was better than when you
were...
                                                      Winnie the Pooh

On Wed, 27 Jul 2011, Tomasz Ostrowski wrote:
> I've managed to install CentOS 6 on a 192MB virtual machine using
LiveCD
> install-to-disk graphical method.
<snip rework of Anaconda, Live CD discussions>

I think you are over-thnking this.  Anaconda is overkill if 
all you want to do is blow images onto arbitrary hardware

So long as you are going through all this, why not just 
install to taste into a chroot with yum or RPM, rsync into a 
prepared hard drive, optionally fix up the fstab grub.conf 
settings, and run grubby or do a mkinitrd and grub 
initialization

(The transfer and bootloader fixup my be done with a minimal 
image, PXE loaded, so one does not even need a working CD/DVD/ 
USB port.  PXE has been on substantially all hardware built 
for the last decade)

That approach is portable, and works across all CentOS 
variants

-- Russ herrold