Question Regarding "update MBR" Option

Discussion in 'Paragon Partition Manager Product Line' started by pamelab, Oct 20, 2009.

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  1. pamelab

    pamelab Registered Member

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    Both partition manager 9.5 and hard drive manager have a feature called "update MBR" included. I assume that this is to replace a corrupted MBR or one that has been compromised by a virus. Sounds like a good feature. However, I have some questions.

    1. Assuming the MBR is not functional, how can this feature be accessed, since one will not be able to boot into the windows version? I do not see it on the emergency disk that the program can create.

    2. I have successfully incorporated the program into a BartPE disk, such that it can be run if the HD is not bootable. However, when I access this option from the BartPE CD, the program simply asks is I want to update the MBR. The question is- will it update the MBR with a windows XP version of the MBR or a vista version ( it is my understanding that version 9.5 will work with bot XP and vista)?

    3. Since my BartPE is windows XP with SP2 based, will the MBR automatically be updated wtih an XP version? If this is so, how would one update the MBR with a vista version, since my HD would not be bootable and an external version of partition manager that has the update MBR may not be feasible?

    I guess my questions boil down to how does the update MBR option decide what version of windows to update to.

    Regards
    Pamelab
     
  2. Robin A.

    Robin A. Registered Member

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    The MBR is independent of Windows, it just directs the boot towards the active partition.
     
  3. Paragon_Tommy

    Paragon_Tommy Paragon Moderator

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    Hello pamelab,

    Since you have PM 9.5, boot to the any of the recovery disk, I recommend using the Linux/Dos disk created by going to Tools > Recovery Media Builder.

    The boot corrector feature in the Linux CD will search for all active operating system on your hard drive and reconstruct the MBR accordingly.

    If the boot correct feature is not available on your CD, from a recovery disk, right-click "Basic Hard Disk 0" and the option to "update MBR"
     
  4. pamelab

    pamelab Registered Member

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    I have done an number of searches and I am admittedly confused. In many cases, people suggest that the MBR's from xp,vist,7 are not interchangble. Below is a exert from the following site.
    http://www.vistax64.com/vista-general/134441-vista-mbr-vs-xp-mbr.html

    "In the Vista MBR and the boot process there is a bit more than the old
    routine of the Master Boot Code simply passing the instructions to the
    Partition Boot Code, there is a whole new element that isn't used at all
    on older NT versions! The paper will explain in part why a previous
    Microsoft MBR cannot (or might not?) boot Vista. One thing for sure,
    with the exception of certain hardware constraints the NT boot process
    has changed little from NT3.51 through to XP, the Vista boot process is
    entirely different, it brings in some never seen before concepts, at
    least never seen before on Microsoft operating systems. This is no
    longer the same "old" NT boot process!".

    regards
    pamelab
     
  5. SIW2

    SIW2 Registered Member

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    Hi pamelab,

    Standard mbr code will hand control to the Vista/7 bootsector on the Active partition perfectly well.

    The bootsector code ( inside the partition) needs to be NT6 compatible in order to hand control to bootmgr - that is not affected by the Paragon rebuild mbr function, of course.

    Hope it helps.
     
    Last edited: Oct 20, 2009
  6. pamelab

    pamelab Registered Member

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    Thank you all for your replies. From your replies, I take it the MBR that partition manager updates of the MBR should be independent of the windows version. I assume that one would try to use this feature (updating the MBR) of PM to replace a virus corrupted MBR etc. . It is my understanding that the partition table is also included in the MBR, and as such a standard/generic MBR update on PM9.5 would update it with a standard/generic version of the MBR. However, it would seem then that the HD/boot process would not know the partitioning scheme that the unbootable and previously partitioned HD has. As a consequence, would the data on the HD with the corrupted MBR/partition table be unreadable also with some sort of updated generic MBR from PM?

    Sorry fo all the dumb questions.
    pamelab
     
  7. SIW2

    SIW2 Registered Member

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    Hi pamelab,

    There are no dumb questions - only dumb people who don't ask.

    I am just a happy user - so someone from PSG will correct me if I am wrong - but as far as I know - the partition table remains as is. I assume it operates in a somewaht similar way to MS bootrec /fixmbr from the Vista /7 system recovery options.

    Also only use to replace a non - standard mbr. Clearly, then, a standard mbr is fine.

    http://support.microsoft.com/kb/927392

    In case you are interested in that kind of thing there is a little free app. called plpart32 to modify the partition table from here:

    http://www.plop.at/en/windowstools.html

    Hope it helps.
     
    Last edited: Oct 21, 2009
  8. pamelab

    pamelab Registered Member

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    Still somewhat confused. It is my understanding from a number of sources ( 0ne of which I list below with a small exert) that the MBR contains the primary partition table as part of it.

    "The MBR is not located in a partition, it is located at a Main Boot Record area in front of the first partition.

    When a data storage device has been partitioned with the MBR Partition Table scheme (i.e., the conventional IBM PC partitioning scheme), the master boot record contains the primary partition entries in its partition table. The partition table may also contain entries for other, secondary partitions which are stored in extended boot records"

    http://74.125.113.132/search?q=cach... table part of MBR?&cd=70&hl=en&ct=clnk&gl=us

    If this the the case, then it would seem that the generic MBR would not know how the HD is partitioned and the partitions would not be accessible. While the referred to Microsoft programs can TRY to fix the MBR, there are numerous references on the internet to individuals unsuccessful attempts to get back data after a damaged partition table. That the primary partition table resides in MBR would seem to be consistent with one of the MBR's functions of pointing the booting to the primary partition that contains things like boot.ini and ntldr on this partition for XP.

    Which brings me back to what the possibly corrupted MBR ( containing the primary partition table) is being replaced with with partition manager 9.5, when the option to "update MBR" is chosen, which I assume contains some sort of generic MBR.

    Sorry for my confusion and appreciate the answers you are providing
    regards
    pamelab
     
  9. SIW2

    SIW2 Registered Member

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    Hi,

    The MBR consists of 2 parts - executable code, and the partition table.

    Confusingly, when people ( i.e. MS ) talk about rewriting/updating the mbr - what they really mean is the executable code - leaving the partition table untouched.

    Software for windows tends to follow the MS descriptions.

    If you have an invalid partition table - typically you use a partition undelete tool . It searches for evidence of previous partitions. You select which you want to "recover" - the tool then writes the partition table to reflect that.

    They are separate functions.

    Hope it helps.
     
    Last edited: Oct 22, 2009
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