"EISA Configuration" partition won’t go away

The symptom is typical: you check out the partitions on your hard drive in Windows Disk Manager only to find out that there’s a weird, inaccessible partition that’s of the type “EISA Configuration.” What is it? Can I get rid of it?

What is it?

It has become standard practice for manufacturers to include recovery data or utilities on the hard drive to save them the costs of creating separate recovery disks for your computer. The benefit is that you can always restore your computer without worrying about losing your restory disks, but the downside is that it’s taking space on your hard drive, and if your hard drive died, you don’t have any restore disks at all.

The “EISA Configuration” partition is not really an EISA Configuration partition. EISA is an obsolote IBM bus architecture. What’s really going on is that this partition is a regular FAT32 or NTFS partition, except that its identifier in the partition has been changed to 0xDE, which codes for “EISA Configuration.” This way, Windows doesn’t try to mount it so you won’t accidentally mess with the files there.

How do I get rid of it?

Just delete it. You may be able to delete this partition and then expand your regular Windows partition to fill the gap using Windows Disk Management MMC snap-in. Just right-click on “My Computer” and select “Manage…” and find “Disk Management.”

Personally, I recommend using an Ubuntu live CD. With it, you can boot into Ubuntu, run GParted (a partition editor), delete the EISA Configuration partition and expand the Windows partition to fill in the remaining space. Just be careful with your data. Make a backup.

It won’t go away!

You may experience an issue where, after deleting your “EISA Configuration” partition, you boot your computer only to find out that another partition has magically turned into an “EISA Configuration” partition. What happened here was that the manufacturer (Acer has been known to do this) put a small program in the Master Boot Record (MBR), the first 512 bytes of your hard drive. Every time you boot that hard drive, their program runs and blindly changes the first (usually it’s the first one) partition on the hard drive to 0xDE, which codes for “EISA Configuration.” Bad.

What you need to do is write in a new MBR to get rid of this program. Be careful, because the MBR stores the partition table, without which your computer won’t know what partitions exist on your hard drive. There are several tools that can do this; I won’t go into detail on each one.

Now my computer won’t boot!

If Windows displays an error message saying that “hal.dll” could not be found (Windows XP) or that “rundll32.exe” could not be found, then what likely has happened is that your partition numbers have changed and Windows can’t find itself anymore. On XP, if you know what you’re doing, you can edit the “boot.ini” file to point to the new partition number. On Vista, you’re best off just running the automated recovery on the Vista Recovery Console disc until it’s fixed. It might take several tries.

My drive C: and D: got switched!

It’s a regrettable problem when Windows, which originally was on the C: drive, suddenly gets switched to the D: drive. You’ll find that a lot of things don’t work like this, but unfortunately, you can’t go into Disk Management and change the drive letters because you’re currently running Windows off that drive letter. Microsoft has a KB article detailing the procedure to switch them back, but the process is simple.

Fire up regedit.exe and navigate to HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices, and rename the \DosDevices\C: and \DosDevices\D: keys around. Or, you can delete all the keys in MountedDevices and Windows will automatically enumerate the partitions and reassign drive letters.

3 Responses to “"EISA Configuration" partition won’t go away”

  1. Keith Pitts writes:

    Thanks for the article, covers most eventualities, just one more to add to the list if I may. I was suffering from a failed dual boot (Windows Vista / Windows 7). After installing Windows 7 RC the dual boot disappeared, when viewing the other boot drive it was set as ‘EISA Configuration’. Not really a problem as I keep data on seperate drives – but you never know ! All I wanted to do was view the files on the ‘missing’ drive for my own piece of mind. After much googling and finding solutions that require the purchase of expensive pieces of recovery software, I took my life (and my hardrive) in my hands, ran diskpart in an elevated command prompt, navigated to the disk\partition in question, viewed the details – it was set as a type 12, used the command ‘SET ID=07 OVERRIDE’ and magically the ‘EISA Configuration’ drive was available as a normal, viewable drive, allowing me to view the files (didn’t find anything!).

    Anyway hope this is of use to somebody in a similar position, I would guess that in a situation ALA Acer you would get access to the drive during the current windows session as it will be reset to ‘EISA Configuration’ on re-boot.

  2. aaron terry writes:

    Got my drive letter back. EasyRE created partion type 12(Configuration/diagnostics)
    Partion types: https://www.win.tue.nl/~aeb/partitions/partition_types-1.html

  3. john henderson writes:

    I have just completed a factory reset on my acer aspire vista 32bit home premium,i have the original HDD installed,i also had a 2TB HDD instaled,to which i backed up all my important stuff,drivers,program info files,design folders for pcbs,front and rear panel designs for audio equipment,i design audio amps for musicians,dvd folders around 100 films,etc,once the reset had taken place,i accessed the 2TB HDD to retrieve google chrome installers and anti virus installers,that was fine,after it restarted,i was awareof this by the sound beeps on restart as i changed to my xp machine via the flat panel tv i use,HDMI 1,HDMI 2,inputs,when i opened “my computer” the 2TB HDD was gone,im not too computer savvy,but this has happened before,then i disconnected the HDD,and as then and now the HDD is EISA,i have read other posts and they seem to be for OS partitions,im not at all sure how to proceed,and if i can possibly get the data from both HDDs back again,that would save around 3-4 years of work,not least the cost of a 2TB HDD and a 1.5TB HDD.could a proceedure to fix be given please,like i said ,im not too savvy with computers,as in registry fixes etc.thanks.

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