More than 3 OS's?

Discussion in 'Acronis Disk Director Suite' started by Perderabo, Jul 20, 2006.

Thread Status:
Not open for further replies.
  1. Perderabo

    Perderabo Registered Member

    Joined:
    Jul 20, 2006
    Posts:
    4
    I am trying to install multiple OS's on my laptop. Getting to three is easy. But then I bump into the ceiling. With only 4 entries in the MBR, I can have 3 primary partitions and then the fourth is an extended partition to point to a chain of logical partitions. I have plenty of disk space, but each OS wants to be installed in a primary partition. I have tried installing in a primary and then moving to a logical but this did not work. The copy would hang on boot.

    I have a crazy idea that might work. Start over and install XP in a primary partition. Create a bunch of logical partions. Edit the partition table to to make the 3rd entry a primary partition that overlays a logical partition. Install in this pseudo-primary.

    But there must be some other way to get this to work. If it matters, I would like XP pro, FreeBSD, DesktopBSD, Redhat 8, Fedora Core 5, and Solaris 10. I need two more partitions, one for a fat fs to pass files around from os to os, and a second for an raw Oracle database. My box says "install 99 or more operating systems on a single PC". My modest requirements should be a piece of cake, right? ;)
     
  2. Perderabo

    Perderabo Registered Member

    Joined:
    Jul 20, 2006
    Posts:
    4
  3. K0LO

    K0LO Registered Member

    Joined:
    Mar 9, 2006
    Posts:
    2,591
    Location:
    State College, Pennsylvania
    Pederabo:

    Interesting article. Thank you for the link. You really dug deep into the disk structure to understand what's going on. But isn't there an easier way?

    It seems to be a common misperception that Windows XP must be installed to a primary partition. Not so. I think that some of the older Microsoft operating systems may have had this limitation but not XP.

    Only XP's bootloader (ntldr) and boot.ini files need to be in a primary partition and only if you're using the standard Microsoft Master Boot Record (MBR). This simple MBR searches the partition table for the active partition and boots it.

    More versatile bootloaders like GRUB can boot almost any OS no matter where the OS is located. So by not using the Microsoft MBR you can get around the primary partition limitation and install XP to a logical partition. GRUB excels at doing this; just install it to the MBR and then point GRUB to the right partition. Let's assume that XP is in the first logical partition (hda5):
    Code:
    rootnoverify (hd0,4)
    chainloader +1
    should work. For Linux, all you usually need to do is to point GRUB to the kernel file and the initrd file, no matter where you put them. So all of your Linux installations can also go in logical partitions.

    So for a multiboot system with a large number of operating systems installed, couldn't you install GRUB to the MBR and then put everything else in logical partitions? By doing this you'll not bump into the 4-partition limit.
     
  4. nuljet

    nuljet Registered Member

    Joined:
    Sep 27, 2006
    Posts:
    63
  5. K0LO

    K0LO Registered Member

    Joined:
    Mar 9, 2006
    Posts:
    2,591
    Location:
    State College, Pennsylvania
    That is a very interesting article! Definitely a keeper.
     
  6. Perderabo

    Perderabo Registered Member

    Joined:
    Jul 20, 2006
    Posts:
    4
    Very interesting link indeed! Thanks for posting that. Because I am using a laptop I have some restrictions that the author did not have. I have, at most, 2 hard drives. And my 2nd hard drive is in a removable front bay. That front bay can hold a 2nd battery, a floppy drive, a zip drive, and a second DVD burner as well. And I have 5 different hard drives that fit in the front bay (one at a time). I want the 2nd drive to be optional and not needed for booting. Thus I must fit all of my OS'es on a single hard drive. I want this primary drive to be as fast as possible. And bear in mind that a laptop needs a 2.5 inch form factor drive. That fastest laptop drives are Seagate's 7200 RPM series of drives and the largest one of those is a 100 GB drive. Even if I relax my need for speed, the largest drive becomes 120 GB spinning at 5400 RPM.

    So I am limited to a single 100 GB drive and more importantly, I am limited to 3 primary partitions. I saw several options involved a non-stanard MBR. But a non-standard MBR scares me enough that I won't use one. Bear in mind that the price I paid was one older Solaris version and a few BSD versions that I kinda would liked to have had. I feel that I deserve a medal for agreeing to one Microsoft OS. A second Microsoft OS will never be installed on this box. My primary focus is Linux and there is never any problem installed as many Linux versions as I can fit on the box. Linux happily resides in logical partitions. I want some free space on my primary drive for an Oracle database so I limited myself to only a handful of Linux versions. I am not sure how many Linux install I could squeeze on the box if I pushed it, but I want some room for data too.

    As the author of that linked article pointed out Solaris and BSD want to live in Primary partitions and I bumped into that same problem. Unlike him, I had trouble with NetBSD, but maybe I gave up to soon on that. I may retry NetBSD, bit my desire for NetBSD is lukewarm at best.

    Configuring 8 OS'es is quite a handful for me. I would not want a box with 100 OS'es on it. I did (sort of) want 10 or 11. But I mostly do not feel a great need for more OS'es right now.

    As for XP, I am not an XP expert and I have only used XP Pro. I have no experience with XP Home or XP Media edition. But XP's little bootloader can handle a second copy of XP quite well. If you put 2 copies of XP on one box and use the standard Microsoft bootloader you can get a little grub-like menu that lets you boot either copy of XP. From either version of XP, you can run bootcfg from the command line. Or you can click System Properties -> Advanced Tab -> Startup and Recovery Setting Button. Either way you wind up modifying the boot cfg on the bootable partition. These programs are reading the MBR to locate the Active Partition and then operate on the Active Partition's boot files. A Logical Partition cannot be an Active Partition. I don't believe that this stuff will work with XP sitting in a Logical Partition. I know how to remove the file attributes with attrib, edit the files by hand, and then restore the file attributes with attrib. But I must assert that finding even one OS program that won't work from a Logical Partition is enough to nix the idea for me. I don't know what other Microsoft programs might suddenly decide to scan the Partition Table in the MBR. This kind of stuff is another reason that I shied away a non-standard MBR. Anyway moving XP into a Logical Partition would only allow me one more BSD distro. Again, I am not paying a large price to keep XP in the Primary Partition.

    This laptop is intended as my primary system....it is not an experimental box. And I need to get back to being a user of OS'es and not an installer of OS'es. So I had to make a few compromises here and there. And digging deep into the disk structure and understanding what was going on was actually my primary reward. I am mostly an HP-UX/Solaris guy and I wanted to understand the Intel boot sequence. I feel that I got it now.
     
  7. K0LO

    K0LO Registered Member

    Joined:
    Mar 9, 2006
    Posts:
    2,591
    Location:
    State College, Pennsylvania
    Actually it will work. The only thing reading the MBR to locate the Active Partition is the standard Microsoft boot loader, but you can blow that away if you install GRUB to the MBR and use it as your bootloader. Then you can put Windows XP in a logical partition and boot it from GRUB.

    If you run into anything that won't boot from a logical partition there's a neat workaround. I used this when I loaded up the standalone recovery programs for Acronis True Image and Disk Director into their own little 50 MB logical partition on my laptop's hard drive and then tried booting them from GRUB. To make this work you can use Acronis Disk Director to change the value of "Hidden Sectors" in the partition boot record from its default value of 63 to the absolute sector number of the start of the logical partition. Here's a link to a post I had about how to do this.
     
Thread Status:
Not open for further replies.