What is the 100mb partition Windows 7 SOMETMES creates on install?

[Cyber Akuma]

Windows 7 sometimes automatically asks to create a 100mb partition for system files on startup.

Can anybody tell me just what exactly this partition is? Whats on it? And why sometimes it creates it, and sometimes it doesn't? I've installed Windows 7 on a few systems now, and it seems to be random, what causes it to install and to NOT install this partition? And whats on it? Would it be better to have this partition or not?

Would upgrading from a previous version of Windows but doing a clean install create this partition?

How about installing on a drive that already has existing partitions?

[ninja502]

Windows 7 sometimes automatically asks to create a 100mb partition for system files on startup.

Can anybody tell me just what exactly this partition is? Whats on it? And why sometimes it creates it, and sometimes it doesn't? I've installed Windows 7 on a few systems now, and it seems to be random, what causes it to install and to NOT install this partition? And whats on it? Would it be better to have this partition or not?

Would upgrading from a previous version of Windows but doing a clean install create this partition?

How about installing on a drive that already has existing partitions?

It contains boot files and recovery info & If you delete it you will no longer be able to boot you computer

[Berserk87]

I've never seen it not show up.

Its contains all the boot information and some other stuff.

[Saburac]

I think it's only created by Ultimate and Business, and only when you install on a bare unpartitioned drive.

[John.D]

Its for bitlocker

[Snowl]

its for recovery

[tsupersonic]

I think it's only created by Ultimate and Business, and only when you install on a bare unpartitioned drive.

Nope, not at all. It's created for the reasons the others mentioned.

[hdood]

He's part right. It is the default system partition created only on empty drives. It holds the boot loader and BitLocker files (if enabled. because you couldn't boot from an encrypted partition) and clearly separates the system partition (which holds the boot loader) from the boot partition (which holds the OS).

If you already have partitions, it will normally make the first NTFS partition on the disk the system partition instead.

It does not contain any recovery stuff, that is located on the boot volumes of the OSes installed (it is OS-dependent and too large to fit on a 100MB partition).

[+Anarkii Subscriber²]

Its for Hazars loader files....

[pnypt]

nice one!

[ReDFoX2200]

it is for bitlocker, you can remove it by using windows vista to partion your drive.

I have removed it and I have no issues at all :)

[Pikey]

I've always used a pre-partitioned drive , so I never see it.

[lt8480]

It places it on completely empty computers. If you have another hard drive with a boot sector and another version of windows installed it does not create it.

[Cyber Akuma]

It places it on completely empty computers. If you have another hard drive with a boot sector and another version of windows installed it does not create it.

My friend's laptop had Vista installed, I was helping him install an upgrade version of Win 7, I told it to delete the Vista partition and use the entire drive, it added the 100mb partition.

[John.D]

I usually delete all the partitions then recreate then (about 80 GB each, during the install). Or if the hdd hasnt been formatted yet, I just create the separate partitions. It probably couldnt create the 100mb, even if it wanted to. Well, I cant see any 100mb partitions on this

[hdood]

My friend's laptop had Vista installed, I was helping him install an upgrade version of Win 7, I told it to delete the Vista partition and use the entire drive, it added the 100mb partition.

Exactly, because when you tell it to use the entire drive, it is dealing with an empty drive that it can do whatever it wants to. If there is something else on it, it can't. If people don't want the partition, the best way to avoid it is to manually create your own partition through the installer and then install to that rather then just clicking next/telling it to use the entire drive.

[lt8480]

My friend's laptop had Vista installed, I was helping him install an upgrade version of Win 7, I told it to delete the Vista partition and use the entire drive, it added the 100mb partition.

In this instance you told it to clear the computer and then install Windows 7.

If your Vista install was on another hard drive with a boot sector of its own, and then you told it to install on another drive leaving Vista in its place it would not have created the 100mb partition.

[Cyber Akuma]

In this instance you told it to clear the computer and then install Windows 7.

If your Vista install was on another hard drive with a boot sector of its own, and then you told it to install on another drive leaving Vista in its place it would not have created the 100mb partition.

I see.

Because both the systems I want to install it on have existing partitions.

My Mac Mini will of course have a MACOS partition, and my laptop already has a Ubuntu and OpenSUSE partition.

So I won't be able to get this 100mb system partition on either of them? I know I can delete the Vista partition on my laptop when I install Windows 7 but im not sure if its ok to delete the Windows partition that Boot Camp makes on my Mac Mini when installing windows.

[1WayJonny]

The correct answer for this is because of:

You have one of a few things enabled or maybee all (not that you, yourself enabled it)

1 ) Computer motherboard chipset is set to AHCI in the bios

2) You have a EFI motherboard which the 100MB will store drivers and other data theoretically, not in use very much yet. Not even on a apple machine. Only x86 hackers have made use of this in mainstream

3) Some manufacturers make a system reserved parition with data which is usally a few gigs, since you said it was 100MB only so this is not correct, just a possible use

4) You bios does not have ACHI enabled but the system manufacturer may have used an image with ACHI enabled while cloning drives and you machine gets it by default which would not effect your system from booting... i think

5) This does not have to do with your MBR, as a GUID disk or a MBR formatted disk both will get the 100MB if AHCI is enabled

it will be answer ONE most likley, you can reformat the drive and delete the partition but if ACHI is enabled in the bios it will put the 100MB back everytime.

I can not tell your exact reason for having it with out the PC in front of me but its ONLY the options above. The reason it exist in GENERAL is because its a 100MB parition to be used as a boot loader. As of now not many companies use.

Apple or Microsoft can make use of them but they dont as of now really.

Recent or future used of the 100MB EFI/SYSTEM partition are

1) OSX86 Drivers that site in the EFI until after OSX loads, then OSX will load all drivers in the EFI parition while leaving the OSX install 100% unmodified. This how the OSX86 people get the software update to work as the OSX install is untouched.

Bootloader use

2) Digital Cable Tuner Hack

Loads the bios and OCUR hack and smooshes together to make a hacked OCUR BIOS that the ATI DCT digital cable card reader can use so you watch Digtal Cable on your PC with out the OEM requirement.

Bootloader use, also Microsoft just released an update to Windows 7 in which you no longer need this "Media Center has a new Digital Cable Advisor" which will eliminate the need for this hack and now sizpack joe can have a Cable Card in his PC as like 2-3 weeks ago.

3) Microsoft I heard will be using this parition for Bitlocker Encryption data

Again yet bootloader use.

You gain nothing be deleting it expect 100MB back, with all the possible REAL uses of it I would advise to leave it esp with how much hard drive space people have now a days. I am all for not wasting hard disk space but this has many reasons to keep it.

Cheers

Edited November 22, 2009 by 1Way Jonny

[1WayJonny]

I see.

Because both the systems I want to install it on have existing partitions.

My Mac Mini will of course have a MACOS partition, and my laptop already has a Ubuntu and OpenSUSE partition.

So I won't be able to get this 100mb system partition on either of them? I know I can delete the Vista partition on my laptop when I install Windows 7 but im not sure if its ok to delete the Windows partition that Boot Camp makes on my Mac Mini when installing windows.

Your mac is EFI enabled with ACHI by default, you do have a 100MB parition called EFI (if you havent seen it), your Windows parition does not see it as its already there for your OSX install and also that your mac uses a custom boot loader while working with the EFI BIOS to boot your windows setup.

[hdood]

You gain nothing be deleting it expect 100MB back, with all the possible REAL uses of it I would advise to leave it esp with how much hard drive space people have now a days. I am all for not wasting hard disk space but this has many reasons to keep it.

On your average system it serves no real purpose. All it has on it is a few megabytes of boot loader files. If you did delete it, you'd have to install the boot loader on the boot partition instead and set that active. Possible, but not really worth the hassle. If you don't want it, manually partition the drive during installation. It's that simple.

[Brandon Live Veteran]

On your average system it serves no real purpose. All it has on it is a few megabytes of boot loader files. If you did delete it, you'd have to install the boot loader on the boot partition instead and set that active. Possible, but not really worth the hassle. If you don't want it, manually partition the drive during installation. It's that simple.

Don't do that. Windows creates a separate boot partition for a reason. Lots of other OSes do the same thing. Don't mess with it.

The correct answer for this is because of:

Err, no. The Windows boot partition has nothing to do with the GPT Protective Partition found on most EFI / GPT systems (like Macs), nor is it related to the EISA or other recovery partitions provided by various OEMs.

It is more comparable to the common "/boot" partition created by some Linux installers.

[Phantom Helix]

My Mac always uses a 200mb EFI partition, and the 64bit Windows Vista and 7 are EFI enabled OS's if the hardware supports it anyway

and the windows 7 installer is now notifying us that it is going to do this so "WE" the consumers don't keep asking on forums "Where is the last 100mb of my clean install on this HDD" where as before it did it anyway without you ever knowing it happened

[hdood]

Don't do that. Windows creates a separate boot partition for a reason.

Like I said, I wouldn't bother doing it because it's an irrelevant amount of space. I'm just pointing out that if you really want to save the 100MB, you're better off doing it during the installation. I think you're exaggerating slightly when you say "don't do that" though. Other than make it harder to accidentally delete the boot loader, I don't see what it offers your average PC user.

Lots of other OSes do the same thing. Don't mess with it.

Do they? I can't think of any that do. No Linux distribution that I've tried do, FreeBSD doesn't, and, well, what other OSes are left that have any relevance today. I don't think it's common at all to have the boot loader on a separate partition.

[Fred 69]

It'd be great if people could cite sources from Microsoft.

I don't have any but from researching last time I thought I found out that it held the recovery data. Not the GBs worths that you find on an OEM computer with the ability to "reformat" and reinstall as was when bought but what you boot in to when your computer doesn't boot that holds the necessary tools to repair a computer such as diskpart, etc.

It could make sense that this only appears in Ultimate as my copy at home has it but my laptop (Professional) doesn't for BitLocker.

I really can't be arsed looking for sources as this is just from memory but it'd be great if people debating would to arrive at a proper conclusion.