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Need help Understanding A message from PM 8

Discussion in 'Other PC Software' started by BillyBob, 2004/07/15.

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  1. 2004/07/15
    BillyBob Lifetime Subscription

    BillyBob Inactive Thread Starter

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    If this should be in a different forum feel free to move it.

    I used Partition Magic 8 the other day to resize partitions on my HD.

    I was able to downsize the D: drive etc. with no problems.

    But when I attempted to resize the C: drive I got a warning that moving the OS partition above 1024 cylinders and may cause problems.

    I started with 6.4gig and wanted to go to 10gig or better. I wound up stopping at 8.4gig. And had to resize the D: drive etc. to use up the space.

    This is all new to me and I do not understand it.

    Would this have happend if I had done it in DOS ?

    BillyBob
     
  2. 2004/07/15
    Steve R Jones

    Steve R Jones SuperGeek Staff

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    The following looks interesting if you can understand it...Did you look look in PM's help file?


    4.1 BIOS Disk Access and the 1024 cylinder limit
    Linux does not use the BIOS, but some other systems do. The BIOS, which predates LBA times, offers with INT13 disk I/O routines that have (c,h,s) as input. (More precisely: AH selects the function to perform, CH is the low 8 bits of the cylinder number, CL has in bits 7-6 the high two bits of the cylinder number and in bits 5-0 the sector number, DH is the head number, and DL is the drive number (80h or 81h). This explains part of the layout of the partition table.)

    Thus, we have CHS encoded in three bytes, with 10 bits for the cylinder number, 8 bits for the head number, and 6 bits for the track sector number (numbered 1-63). It follows that cylinder numbers can range from 0 to 1023 and that no more than 1024 cylinders are BIOS addressable.

    DOS and Windows software did not change when IDE disks with LBA support were introduced, so DOS and Windows continued needing a disk geometry, even when this was no longer needed for the actual disk I/O, but only for talking to the BIOS. This again means that Linux needs the geometry in those places where communication with the BIOS or with other operating systems is required, even on a modern disk.

    This state of affairs lasted for four years or so, and then disks appeared on the market that could not be addressed with the INT13 functions (because the 10+8+6=24 bits for (c,h,s) can address not more than 8.5 GB) and a new BIOS interface was designed: the so-called Extended INT13 functions, where DS:SI points at a 16-byte Disk Address Packet that contains an 8-byte starting absolute block number.

    Very slowly the Microsoft world is moving towards using these Extended INT13 functions. Probably a few years from now no modern system on modern hardware will need the concept of `disk geometry' anymore.
     

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  4. 2004/07/15
    best5

    best5 Inactive

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    hello BillyBob,

    I know you're a very experienced user but I wish to say a few things which may help some day other people reading this forum. At first I guess it should be said again that Partition Magic is a DOS program, even it can be started in Windows; it will always do its job in pure DOS. Besides, when started in Windows, it can make a lot of troubles - I know it for certain :( So, there are at least 2 strong reasons to use it only in its DOS version.
    It's good to label the drive(s) where OS is(are) installed, otherwise they will
    apear as *: or as noname and this may create confusions.
    I shall describe below in some details the way I do this job :
    -I labeled the drive where my Win98SE is installed 98SE. When is active it apears as C:98SE
    1-format first C: and D: then resize D: from L > R *. It will result an unallocated area
    2-at unallocated area of HDD >create partition > FAT32 > primary
    3-label N (or otherwise) the new primary FAT32 partition
    4-merge > choose N FAT32 becomes a folder of C:98SE (FAT32)
    5-Folder Name :98SE

    that's all


    Note:

    1- Only if you already have an image of C: (Ghost / Drive Image) and also can move temporarily the stuff from D to other partition. It's true that PMagic is able to do all its jobs without spoiling data, but it's slow at moving data. We need less time to move data from D to E and back and also to restore the system from a GHO / PQI image to C:

    *when resize from L > R it takes less time to create the new partition (in this case)

    good luck

    Stefan
     
  5. 2004/07/15
    BillyBob Lifetime Subscription

    BillyBob Inactive Thread Starter

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    Which I do not LOL

    But I figure the limit and the warning are there for a very good reason. So I feel to be in my best interests NOT TO ignore it.

    First & Foremost. FORMAT is 100% out of the question. FORMAT is a NASTY word that I have only used on a brand spanking new, never before used HDs for YEARS.

    Not only does D: need downsizing L to R but so does the extended partition that holds D: E: F: G: H: That part all went fine.

    I will work with things the way they are before I will even THINK about formating. I have too many years of HARD/time consuming work involved and also a 4 machine LAN that is working and I ain't gonna GAMBLE on having to do it all over AGAIN.

    BillyBob
     
  6. 2004/07/16
    r.leale Lifetime Subscription

    r.leale Well-Known Member

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    Hi Billy-Bob,

    This is a standard PM warning which appears whenever you try to resize 'C'.
    I re-sized my 'C' partition from 1.5 GB to 2 GB last week, got this warning as well. Nothing evil happened, and I now have a larger 'C' partition.
    Back-up just in case, and go ahead. The PM handbook does mention changes to 'C' drive, (on page 12) but just to point that it must be carried out in boot mode.

    Roger
     
  7. 2004/07/16
    r.leale Lifetime Subscription

    r.leale Well-Known Member

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    Me again Billy-Bob,
    Your question started me thinking, so I did a little research at Power Quest, and found the following:

    QUOTE
    The 1024 cylinder limit only applies if:-
    # You have a hard disc of more than 504 MB.
    # The hard disc was manufactured before (approx) 1994.
    # The BIOS in your system does not have the INT 13 BIOS extensions built in.

    If you have such a system and you use only DOS, neither the DOS FDISK utility, nor any Power Quest product, allows you to see cylinders beyond the 1,024th cylinder, or include them in any partition. Space beyond the 1,024th cylinder always remains invisible.

    END QUOTE

    So, if you can see, and use your disc beyond the 1,024th cylinder limit, (which is marked in the PM graphic), you can ignore the warning.
    I hope that reassures you a bit,

    Rogerhttp://www.windowsbbs.com/newreply.php?do=newreply&noquote=1&p=172128#
    Cool
     
  8. 2004/07/16
    BillyBob Lifetime Subscription

    BillyBob Inactive Thread Starter

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    r.leale

    Thank you.

    So.

    If PM 8 shows C: drive. The full extended partition containing D: E: F G: H: and all their info I should be able to ignore that warning and downsize D: and the extended partition and then upsize C:

    Oh BTW. All drives are named ( labeled )

    And yes there were two v v ( min and max I guess ) shown.

    It sure as heck helps.

    But as I said in my previous reply I will remain Status Quo before I even think about Format. YUK !! I hate that word. ( after a system is built anyway.

    BillyBob
     
    Last edited: 2004/07/16
  9. 2004/07/16
    r.leale Lifetime Subscription

    r.leale Well-Known Member

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    Hi Billy-Bob,
    Yes, there are two sets of black markers. The first pair are the 2 GB boot boundary, the second pair is the 1024 cylinder marker. If you have enough unused space in 'D' to guard the data it contains, and have enough left to let the defrag work, you will have no problem in making 'C' bigger.

    Roger :)
     
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