Viewing MBR and Partitions

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Viewing MBR and Partitions

I just replaced the HD on my iMac running Max OS X version 10.5.2. Upon running Boot Camp Assistant I was faced with a confusing situation when asked which partition I wanted to install Windows XP on. I contacted Apple Support to try to "fix" this problem and was told I could download a tool to look at the MBR and reformat unnecessary partitions. I was referred to the following link: http://www.info.apple.com/kbnum/n306496. The series of articles boggled my mind and I could not find a way to view the MBR, let alone understand it. How can I view the MBR and delete unnecessary partitions? Details of what the Windows Installed showed follow.

I have a 250 GB HD. My options were:

476,946 MB on disk [MBR]
I: Partition1 [unkown] 476,946 MB {476,950 MB Free)
238,473 MB Disk0
J: Partition1 [unknown] 200 MB 200 MB free
K: Partition2 [unknown] 205,696 MB 205, 696 MB free
Unpartitioned Space 128 MB
C: Partition3 (Bootcamp) 32,451MB 32,434 MB free (this appears to be a previous version of boot camp that was restored when I used Time Machine to restore my HD.)

These partitions do not show up when using the Mac's Disk Utility.

iMac, Mac OS X (10.5.2), 2.16 GHz Intel Core 2 Duo processor

Posted on Mar 14, 2008 6:32 PM

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Answer 1

Kappy

Level 10

362,007 points

Mar 14, 2008 6:56 PM in response to Art-LA

Your new drive is not prepped correctly. Do this:

Extended Hard Drive Preparation

1. Open Disk Utility in your Utilities folder. If you need to reformat your startup volume, then you must boot from your OS X Installer Disc. After the installer loads select your language and click on the Continue button. When the menu bar appears select Disk Utility from the Installer menu (Utilities menu for Tiger or Leopard.)

2. After DU loads select your hard drive (this is the entry with the mfgr.'s ID and size) from the left side list. Note the SMART status of the drive in DU's status area. If it does not say "Verified" then the drive is failing or has failed and will need replacing. SMART info will not be reported on external drives. Otherwise, click on the Partition tab in the DU main window.

3. Click on the Options button, set the partition scheme to GUID (only required for Intel Macs) then click on the OK button. Set the number of partitions from the dropdown menu (use 1 partition unless you wish to make more.) Set the format type to Mac OS Extended (Journaled.) Click on the Partition button and wait until the volume(s) mount on the Desktop.

4. Select the volume you just created (this is the sub-entry under the drive entry) from the left side list. Click on the Erase tab in the DU main window.

5. Set the format type to Mac OS Extended (Journaled.) Click on the Options button, check the button for Zero Data and click on OK to return to the Erase window.

6. Click on the Erase button. The format process will take 30 minutes to an hour or more depending upon the drive size.

Steps 4-6 are optional but should be used on a drive that has never been formatted before, if the format type is not Mac OS Extended, if the partition scheme has been changed, or if a different operating system (not OS X) has been installed on the drive.

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Answer 2

Art-LA Author

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Mar 14, 2008 10:51 PM in response to Kappy

Thanks Kappy. I guess I was not clear in the description of my problem, or I do not understand your reply. According to Disk Utility, everything is fine: Two partitions: Mac HD and Bootcamp. However, boot camp reports using 31.7 GB when I would think this partition should be empty. On the other hand, when I attempt to install Windows on the bootcamp partition, all the partitions referred to earlier appear. I suspect that the bootcamp partition which was previously installed ** failed to show up when the HD failed, showed up again when the new HD was installed and files restored from Time Machine.

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Answer 3

Kappy

Level 10

362,007 points

Mar 15, 2008 8:39 AM in response to Art-LA

If you created a Boot Camp partition then what's reported is correct. I don't think I understand what problem you think you're having. When you run the Windows installer the Windows formatter displays all the partition information on the drive including the invisible (in OS X) partitions. That's normal. You tab down until you select the C: partition for Windows to format.

You must have partitioned and formatted the new drive properly and used Boot Camp Assistant to create a new Boot Camp partition. Correct? TM does not back up a Boot Camp partition nor is it able to create the partition.

When you installed the new drive and partitioned it did you use the GUID partition scheme? Did you create a new Boot Camp partition on the new drive?

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Answer 4

Art-LA Author

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Mar 15, 2008 10:39 AM in response to Kappy

Sorry for the confusion. Initially, I had set up bootcamp. Originally, the Bootcamp partition showed up when I ran Disk Utility. Eventually, I started having problems and Disk Utility was reporting numerous error messages. Then, bootcamp stopped showing as insalled. I reformatted the disk but problems reoccurred. Eventually, an Apple technician determined my HD was bad and had someone come o my home to replace the HD, As far as I know, he installed the new HD properly. After restoring my machine from Time Machine, Disk Utility indicated no problems.

My problem is that when I tried to install Bootcamp on the new HD, The Windows Installer identified many partitions that were not identified by Disk Utility. The Help Desk person a spoke to over the phone sent me a link to material that was to help me view the MBR and determine exactly what partitions were actually installed and to delete partitions I don't need or want. My problem is that after reading through this material, I missed how actually view the MBR.

The more I think about this, one thing I am doing that may be creating misinformation is that I am trying to install Windows from a runstream DVD. I have Windows XP Professional and a Service Pack 2 DVD. The only version of Windows Xp with SP2 is the runsteam I created. This runstram may be creating false information about how my HD is partitioned.

BTW, using Bootcamp Assistant, I have restored my HD to a single partition and Disk Utilit reports:
Total Capacity : 232.9 GB (250,059,350,016 Bytes)
S.M.A.R.T. Status : Verified
Partition Map Scheme : GUID Partition Table

May be, I should leave well enough alone and forget about bootcamp. I really don't miss Windows and there are only one or two applications I can not run on my Mac.

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Answer 5

Kappy

Level 10

362,007 points

Mar 15, 2008 12:06 PM in response to Art-LA

I'm not sure what your situation is. I still don't know if this drive has one partition, two partitions, an OS X partition and a Boot Camp partition. It's unclear to me if you know for sure what's there. So, I can only offer this.

Open Disk Utility. In the list on the left you should see a drive entry (mfgr.'s ID and drive size) under which will be one or more sub-entries which are the partitioned volumes. If there is only one entry then it should be equal in size to the drive's capacity - 250 GBs. It should have a GUID partition table. This appears to be what you've indicated in your previous post.

In order to install Windows you must now use Boot Camp Assistant to create the Boot Camp partition. From what you've thus far described this is not yet done.

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Answer 6

Art-LA Author

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Mar 15, 2008 5:21 PM in response to Kappy

My current situation is as stated: One partition - 250 GB. I have run bootcamp assistant to partition the HD to install Windows XP Pro. In the process of installing Windows, the Windows Installer, reports numerous partitions as indicated in my original post. These partitions are not seen my Disk Utility. The Mac Help Desk suggested I check the MBR to see if it references several partitions and to delete the partitions I do not need. I was sent a link (see original post) on how do do this. I have been unable to determine from the series of articles in that link, what program I need to download to view the MBR.

So, my question is: How do I view the MBR and if the MBR reports additional partitions, how do I delete them? Again, Disk Utility does not indicate I have more than one partition but the Windows installer reports several partitions.

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Answer 7

Kappy

Level 10

362,007 points

Mar 15, 2008 9:01 PM in response to Art-LA

In the process of installing Windows, the Windows Installer, reports numerous partitions as indicated in my original post. These partitions are not seen my Disk Utility.

As I said at first this is normal. The Windows formatter does not understand a Mac OS format. What you see is normal. You don't need to do anything more than tab down to the C: drive referenced in the list and then select the button to format that partition. The others are irrelevant. You do not delete anything nor do you need to view the MBR.

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Answer 8

Art-LA Author

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Mar 15, 2008 9:29 PM in response to Kappy

Thank you very much for your persistence. I finally understand.

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