[arch-general] Quick question about post-MBR gap?

mike cloaked mike.cloaked at gmail.com
Thu Jul 19 05:17:16 EDT 2012

On Thu, Jul 19, 2012 at 5:33 AM, Martti Kühne <mysatyre at gmail.com> wrote:
> last time I installed arch on a virtual machine, I was unable to install grub2.
> one google search later I put the mbr gap of 2MiB back in place and everything
> went smoothly. 2MiB isn't much by today's standards, and if the software says
> it needs it, why not just give it? if you find a way to avoid it, that would be
> great, although I can think of numerous reasons why that shouldn't work.
> just my two cents.
> cheers!
> mar77i

Indeed it is easy to put a gap between the MBR and the first partition
when partitioning from scratch - the main issue is for anyone with a
pre-existing (non-linux) partition at the start of the hard drive
containing an OEM installed Windows system or HPA recovery area or
similar - what I have done many times in the past is to shrink the
windows partition in a newly acquired desktop or laptop, and then add
in suitable partitions for the linux needs in the newly available
space in the rest of the disc. However what I have usually not done is
to "move" the Windows/HPA partitions at the start of the drive - on
occasions when I have attempted to move them along a bit (say to make
space for a /boot ext4 partition) then booting Windows can give
messages that it is not entirely happy (sic!) - sometimes Windows
"fixes" itself but occasionally not! I have usually ended up dumping
Windows altogether if that happens and repartitioning the drive from
scratch and putting only linux on it and resorting to using Windows on
other machines. However for some people without access to other
machines to run applications that have no linux equivalent it is vital
to keep a functional Windows system - for example updating many GPS
boxes eg from Garmin can only be done via Windows - similarly to
update (officially) the Android system on a Samsung cellphone is only
realistic using Samsung Kies on a Windows machine. There are many
similar examples of the need to keep Windows. Of course for many
seasoned arch users there is nothing to beat it once it is installed -
but unfortunately there still remain some tasks for which linux cannot
be used. I have also tried using Windows in a VM for such tasks and
have frequently come up against problems that are tough to crack.
Hence a dual boot (or dedicated) Windows machine is for me at least a
necessity even though the majority of my work can be done perfectly
well and efficiently with arch.

Over the past ten years I have done somewhere around 150 linux
installs, and many disc partitioning sessions - but maybe others have
a lot more experience than I have! Having been through a certain
amount of pain at times concerning an attempt to keep Windows working
as well as the linux in a dual boot machine, and now seeing a pretty
major change to the bootlloader coming up it is probably sensible to
read ahead as much as possible, and be as prepared as possible for how
to deal with different install scenarios, but also be prepared for
quite a lot of work to recover if it all goes pear shaped during the

I will certainly be doing what I can in this regard and I will also be
doing test installs on a non-critical machine - but I do have a couple
of machines where keeping Windows is essential - and on those machines
I already also have arch dual booting.  I hope that the move to grub2
gives a minimum of problems during the transition period.

mike c

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