2024-04-19

mbr

I can read and write from my SCSI hard disk, but I can’t boot from it

DATARECOVERYUNION.COM02 mins

SCSI Hard Drive Sometimes, the master boot record(MBR) on a hard disk may become corrupted as a result of installing other operating systems or through infection by a boot-block virus. When this happens, you can boot from a floppy (you must have the necessary files) and attempt to re-write the Master Boot Record (Microsoft Windows 95/98/Me/2000/XP only) by typing “FDISK /MBR” (leave out the quotes). If that doesn’t work, there are other ways to purge the MBR through the use of debug routines, SCSI low-level format routines, or the zero-fill utility in your SCSI controller BIOS. Consult your operating system vendor for assistance with this to determine if this is an operating system issue.

Or try these troubleshooting steps:

  • Check all cable connections.
  • Verify twisted-pair cable on any LVD SCSI drives.
  • Test the data cable by trying a different cable.
  • Try the cable on a known working drive.
  • Check the jumper settings.
  • Check the SCSI bus termination.
  • Check the host adapter card default settings.
  • Test the card by either trying a known good card or a known working drive.
  • Check host adapter settings.
  • Set the SCSI transfer mode to asynchronous negotiation and the transfer rate to 10MB/s (or the slowest setting).
  • Make the offending drive the only device in the system and re-test.
  • Run the “low-level” format (SCSI Format) routine if it’s provided by the host adapter manufacturer (data destructive).
  • Try drive in a different system to see if the same results follow.
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Hard drives greater than 2 TB do not work on existing operating systems

DATARECOVERYUNION.COM04 mins

2TB hard drive External USB, eSATA, Firewire, and internal hard drives over 2 TB’s cannot be formatted on Windows 32-bit operating systems using the Master Boot Record (MBR) partitioning scheme. As a result, when you connect drives over 2 TB’s, depending on which interface you are using to connect them to the computer, they may not be recognized at all, they may be only partially recognized, or they may be recognized but you can’t access them. Other issues such as the system locking up or the computer not being able to boot may also occur.

Cause:
This not an external or internal hard drive issue. It is a 2 TB volume limitation caused by the Master Boot Record (MBR) partitioning scheme that has long been used by Windows 32-bit operating systems such us Windows 2000 and XP.

Solution:
In order to use a drive larger than 2 TB’s, you will need an operating system that can partition and format that drive. Windows Vista, Windows XP (64-bit), Mac 10.4, and Mac 10.5 all have this capability through the GUID Partitioning Table (GPT). The GUID partitioning scheme has the ability to partition both internal and external drives far beyond 2 TB’s in size.

Below are some things to keep in mind when considering the use of drives larger than 2 TB’s:

  1. Windows 2000/XP (32-bit) has no issues with Network storage drives larger than 2 TB’s since they are accessed indirectly through the network.
  2. Windows XP (64-bit) only recognizes external hard drives larger than 2 TB’s that are connected by USB.
  3. You need to know in which partition scheme, MBR or GPT, your Windows Vista operating system is installed. If it’s MBR, you will still have the same issues as in Windows 2000 and XP.
  4. Windows 2000/XP will have no problems formatting a 2 TB Raid 1 (Mirrored) drive in the MBR format. However, it will not be able to convert that 2 TB RAID 1 drive to a 4 TB RAID 0 drive.
  5. Likewise, Windows 2000/XP will not be able to convert a 4 TB RAID 0 external drive to a 2 TB RAID 1 drive. You will need the use of a computer running Windows Vista (using a GPT partition), XP (64-bit), or Mac 10.4/10.5 to convert the drive from 4 TB RAID 0 to 2 TB RAID 1.
  6. Windows 2000/XP will not be able to convert any 2 TB, or smaller, GUID partitioned drive to an MBR partition through Window’s Disk Management. This will require a utility, such as DLG Diagnostics, that can write zeros to the drive so it can be partitioned and formatted through Windows 2000/XP.
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Fix MBR in Windows XP and Vista By Yourself

DATARECOVERYUNION.COM08 mins

What is the MBR?

fix mbr A master boot record (MBR), or partition sector, is the 512-byte boot sector that is the first sector (“LBA Sector 0”) of a partitioned data storage device such as a hard disk. (The boot sector of a non-partitioned device is a Volume Boot Record. These are usually different, although it is possible to create a record that acts as both; it is called a multi boot record.) The MBR may be used for one or more of the following:

  • Holding a disk’s primary partition table
  • Bootstrapping operating systems, after the computer’s BIOS passes execution to machine code instructions contained within the MBR
  • Uniquely identifying individual disk media, with a 32-bit disk signature; even though it may never be used by the machine the disk is running on

If, for any reason, the MBR becomes damaged or corrupt, then the operating system will be unable to load. You will normally see error messages like:

  • Error loading operating system
  • Missing operating system
  • Invalid partition table

These messages are definitely not fun, especially if you are not familiar with computers. Most people would automatically assume their computers are dead! However, that’s not true. Being in IT myself, these errors are actually preferably to other types of Windows errors. Why?

Well, it’s actually fairly easy to fix the Master Boot Record in XP and Vista. All you have to do is load up the Recovery Console and run a simple command. All of your data, applications, settings, etc are still intact on the drive and once the MBR is fixed, the computer will load normally.

So how can you repair your damaged MBR?


Here are the steps to follow:

1. First, restart your computer with the Windows XP setup disk in the CD drive. If you don’t have your original disk, borrow one or download a ISO image from a torrent site.

2. When prompted, boot from the CD drive by pressing any key. If Windows loads automatically, you will first have to enter the BIOS setup and change the order of the boot devices to start with the CD drive.

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3. Once the setup loads, you will see the option to press R to repair a Windows installation.

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4. Once the Recovery Console loads up, you will have to type in a number that corresponds to your Windows installation. This is normally just 1. Press Enter and then type in the Administrator password.

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5. Now at the prompt, type in fixmbr. Your damaged MBR will now be replaced with a new master boot record and your computer should now be able to boot properly. Note that you may also want to run the fixboot command to repair the boot sector with a new one.

Also, make sure you only use these commands on a system with one operating system installed. If you have more than one operating system installed, fixmbr and fixboot could mess up everything.

Fix MBR in Vista

In Vista, the procedure to fix the master boot record is a bit different. You have to start up Vista in the Recovery Environment and then run the bootrec command. Here’s how.

1. First, load up the Windows Vista disc in your drive and press any key to boot from the disc.

2. Choose the language, time, currency, etc and click Next. Now click on Repair Your Computer.

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3. Choose the operating system to repair and click Next. When the System Recovery Options dialog comes up, choose the Command Prompt.

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4. Now type bootrec.exe and press Enter. This will rebuild the boot configuration data and hopefully fix your problem. You can also run the command with switches to fix just the master boot record (/fixmbr), the boot sector (/fixboot), or rebuild the entire BCD (/rebuildbcd).

Fix MBR on Windows 7

1. Insert Win 7 installation DVD and boot from DVD drive. While in some older systems you may have to change boot order through system BIOS, most newer systems allow booting from DVD without changing boot order by simply clicking on any key when prompted to doing so.

2. Choose your default “Language”, “Time”, and “keyboard Input” on the first window and click next.

3. You’re now presented with 3 choices. Click on “Repair Your Computer” to gain access to the System Recovery window. Now choose “Command Prompt” in order to run the desired utility which is called “bootsect.exe”. Bootsect is located inside the boot folder so change your directory to boot. Now run “bootsect /nt60 C:\” if you had Win 7 initially installed in the C partition. Alternatively, you can run “bootsect /nt60 SYS” or “bootsect /nt60 ALL” to repair the system partition or all partitions. Eject the DVD, and restart computer. Your computer should now boot Win 7 again.

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