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multiboot hard drive partitions

Best Answer alacran , 04 July 2017 - 05:25 AM


This is a general grub4dos boot menu entry to find and load an ISO from any (MBR) partition on your HDD:

Applies to standard category in Wonko's post # 11. Also applies to all ISO's YUMI can run from general category as "unlisted ISO" (both are the same).
This is your first and more general option to start with, then if your ISO do not boot this way, you need another approach, but always start trying this first..

1.- For 7pe_x86_E.iso on any (MBR) HDD partition root:

title Boot 7pe_x86_E\nRun 7pe_x86_E from HDD
##ISO file must be contiguous on disk in this case, use Wincontig
find --set-root /7pe_x86_E.iso
map /7pe_x86_E.iso (0xFF)
map --hook
chainloader (0xFF)

2.- For 7pe_x86_E.iso into folder Isos located on any (MBR) HDD partition root

title Boot 7pe_x86_E\nRun 7pe_x86_E from folder Isos on HDD
##ISO file must be contiguous on disk in this case, use Wincontig
find --set-root /Isos/7pe_x86_E.iso
map /Isos/7pe_x86_E.iso (0xFF)
map --hook
chainloader (0xFF)

Just Change 7pe_x86_E & 7pe_x86_E.iso with your ISO name.
Additionally you may change folder name Isos with the one you prefer, even a diferent one in each partition as far as you use the right folder name for each ISO contained in it.

This works great for NTFS partitions on HDD's, sometimes you need some little adjusments when running from FAT32 partition on external USB sticks, but this is not your case.

You may try this directly in your grub4dos menu.lst, or if you prefer go to your Yumi (installed on your HDD) Multiboot folder and locate the menu.lst where each one of your non extracted ISO's is called and change it as required and only move your ISO's to your prefered location.


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#26 Wonko the Sane

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Posted 05 July 2017 - 06:27 PM

2) Yes, the idea is that a small (small means - provided that you don't want to store in that partition iso's or install OS's some 100 Mb or less, in the case of string a .iso on it, FAT16 no more than 1 Gb (if the needed space is more, switch to FAT32), and in the case of FAT32  let's say whatever is enough to fit the (single) .iso you want to store there + 100 Mb). A small partition means that it can be cloned/saved (and restored) in no time, even on one of those USB sticks that you surely have, forgotten in some drawer because they were too small, and FAT16  is compatible with *anything* and FAT 32 is compatible with anything but very old DOS versions. 


4) It is NOT Grub. It is grub4dos. :frusty: Yes, the generic idea is that *anything* including the grldr and menu.lst (part of the grub4dos package) should ideally be "as early as possible" on a "as early as possible" partition/volume, the code (in the MBR+following sectors) AND the script (embedded in grldr) that later loads menu.lst both "scan" available devices to find first grldr and later menu.lst, so the earlier they are, the faster will be the initial part of booting. Imagine that you have to look for menu.lst on (hd0,0) i.e. first disk firs partition, d@mn it's not there, let me try (hd0,1) first disk, second partition, d@mn it is not there .... and you find it finally on (hd0,17) :w00t:


6) If it works, leave it as is, no need to change, your setup is so that the MBR AND 17 (if I recall correctly) following sectors at the very beginning of the hard disk are filled with grub4dos booting code. Everything is cool and you will likely have NOT any problem. The issue I raised is/was that while the MBR is (to a certain extent) "sacred land", and programs/tools/OS tend to respect it (mostly) only writing to it "properly" some "proper" data or code, the so called "hidden sectors" (from 1 to 63 on XP and earlier and from 1 to 2048 on Vista and later, usually) are "no man's land", any program may decide to write to them any kind of crap, overwriting the booting code. Of course most programs, like 99% won't do that, and of the remaining 1% one half knows that some bootmanagers occupy more sectors than just the MBR and if they have to use (even temporarily) some of the hidden sectors, they use higher addresses than the first - say - 32, so it's a safe setting , covering 99.5% of cases (completely invented percentage, of course) but not an "as safe as possible one". I have seen people cry when (usually old disk related programs) overwrote sector 12 or 14, but as said nowadays it is a really rare case.


7) Your sintax is "generally OK". It is a "generic" way that works, very suited to (say) a "portable" media, but if you have a "fixed" setup, you may want to "hardcode" the devices and remove the find  --set-root command. Just like previously described for grldr and menu.lst the find command will start scanning all disks and partitions until it finds the .iso file, the delay is usually non noticeable, still if you already know that xx.iso is on second partition of first disk (hd0,1) in grub4dos syntax, you can go directly with :

map (hd0,1)/xx.iso (0xFF)


This is a pet peeve of mine, once you know where something is, you don't go looking for it everywhere, you ALREADY know where it is and just get it.


Moreover (and this might become an issue) if you have two .isos or more generally two files looked for by the find command with exactly the same name in the same path (let's assume for simplicity root) of two different partitions you cannot be sure WHICH one has been found (it is possible to find that out as the scan is made in a given order, of course, but you cannot be sure until you have checked).



... you motivated me to go ahead, to try new different ideas that I have...

So Wonko, receive my sincere gratitude for all your great help and explanations.

Good :), that was the idea, you  are welcome.




#27 alacran


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Posted 06 July 2017 - 05:50 AM

@ Decopi

Of course there is a matter of preferences how and where to install grub4dos on internal HDD or on USB device but I'm going to suggest this way that has worked for me very fine:

On a USB device for recovery install grub4dos on MBR and also on PBR of first partition (more compativility with some Bios and an inssurance in case MBR is corrupted), you may apply this to your Recovery HDD too.

Use grb4dos v0.4.6a:

It is capable of booting non contiguous ISO's, I can confirm booting an ISO having 4 fragments

steve6375 Recommends version 2017-05-15, He Posted this on 2017.05.20


But now I am on the way to change to grub4dos-0.4.6a-2017-06-25 (the very last at the moment)

If you want to update your Yumi Multiboot use grld.exe from grub4dos-0.4.6a-2015-08-25, this is the newest 0.46a I have tested it supports, this was sometime ago, assume it depends on Syslinux version, you may run your own tests, perhaps the author has updated Syslinux version.


If you put last version of grldr.mbr and grldr.pbr on same folder as your BootIce is, this new versions will be used.


Put your ISO's on NTFS partition(s).

Using this file system improves reading/writing from USB devices.

About Wonko 7) on his last post, yes I am totally agree this is the best and faster way when using an USB stick (wich is slower than HDD), and in fact I use this way.

But I do not recommend this for a HDD, as I always put an Isos folder with my favorite WinPE's on any partition of HDD (not always the same, have several PC's) and also frecuently reduce a logical partition to alocate space and create a new one to test an OS (10, Linux distros, RemixOS, etc), I have beeing in the situation PC did not boot fine and partition number where my ISO's were had changed and needed to change back MBR to WindowsNT 6.x using BootIce, but I forgot to make the changes in menu.lst (not a big deal having an USB stick with my tools) but I prefer to avoid this issues.
Just to make sure from where I am booting and loading my menu.lst It is green background for USB and blue for HDD, also ISO's folder name is Iso on USB and Isos on HDD, so can perfectly know what device is booting grub4dos and from what location are the ISO's loaded, sometimes may have an updated version of your WinPE's or tools on HDD and not yet on USB, so it is always better prevent potential troubles.

Glad to know you made things your way. Even if I can not find a logical reason for ISO's on three different partitions, you may use 3 diferent folders and even hide them or just hide the full partition by just removing volume letter, and you never see it from windows. For me 3 partitions for an ISO in each one is a waste, you may need them some time in future, and it is better to prevent. Remember MBR partitioned disk only aloud a maximum of 4 Primary partitions or 3 primary and one extended partition with several logical partitions on it.


#28 Decopi



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Posted 06 July 2017 - 11:23 AM

@ Decopi

I can not find a logical reason for ISO's on three different partitions



@Alacran, once again, thanks for your answer.


My personal reasons or "the logical reason for 3 partitions"... is my learning curve. My HDD and 3 partitions are an experiment for me, a laboratory.

I have a couple of ideas I want to implement. It includes the future possibility of booting a removable device (HDD or USB), that will allow me/other people (users in different physical locations) to boot from this device (with copies/clones of this device), accessing different OS's, folders, apps, ISO's etc, from different disks, partitions, networks etc. In brief: I'll try to build a kind of "key", able to boot different stuff, from different physical locations, for different users.

But, considering that today I'm a basic IT user profile, without know-how... I'm doing this step by step, learning, asking, testing simple and illogical things. Let's say that this is the way I chose to learn how to implement future ideas I have today.


Your menu syntax solved my first problem... and as I already commented yesterday: You saved me!... thanks again!

In the other hand, @Wonko was a kind of teacher for me. I was aware of my "booting ignorance", but @Wonko showed me a couple of doors I need to open and dive in. This is my first time dealing with boot or multibooting, and thanks to @Wonko today at least I have a "mental-map of my ignorance". Today at least I know where to start.


I confess that I still would like to learn and to find an easy way to work with multibooting directly with extracted ISO's (installed software).

But, this week I'll remain focus just on your and @Wonko last answers, in order to finish polishing and improving my present multibooting configuration.


Thanks a lot to you, @Wonko and @Nguyentu.

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