Results 1 to 3 of 3

Thread: Using sfdisk to change partitions numbers, changes not being applied

  1. #1
    Join Date
    Sep 2007
    Location
    England / U.S.
    Beans
    277
    Distro
    Ubuntu 12.10 Quantal Quetzal

    Using sfdisk to change partitions numbers, changes not being applied

    Hi,

    I've included a thumbnail of gparted screenshot to help visualise the following (taken from a LiveUSB of Parted Magic):

    sudo fdisk -l
    Code:
    Disk /dev/sda: 320.1 GB, 320072933376 bytes
    255 heads, 63 sectors/track, 38913 cylinders, total 625142448 sectors
    Units = sectors of 1 * 512 = 512 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Disk identifier: 0x04380438
    
       Device Boot      Start         End      Blocks   Id  System
    /dev/sda1            2048     4196351     2097152   82  Linux swap
    /dev/sda2   *     5244928    30410751    12582912   83  Linux
    /dev/sda3         4196352     5244927      524288   83  Linux
    /dev/sda4        30410752   625139711   297364480    5  Extended
    /dev/sda5        30412800    55578623    12582912   83  Linux
    /dev/sda6        55580672    80746495    12582912   83  Linux
    /dev/sda7        80748544   105914367    12582912   83  Linux
    /dev/sda8       332423168   625139711   146358272   83  Linux
    /dev/sda9       105916416   210774015    52428800   83  Linux
    /dev/sda10      210776064   235941887    12582912   83  Linux
    /dev/sda11      235943936   261109759    12582912   83  Linux
    /dev/sda12      261111808   286277631    12582912   83  Linux
    /dev/sda13      286279680   311445503    12582912   83  Linux
    /dev/sda14      311447552   321933311     5242880   83  Linux
    /dev/sda15      321935360   332421119     5242880   83  Linux
    Partition Table (sudo sfdisk -d /dev/sda > Desktop/PT.txt)
    Code:
    # partition table of /dev/sda
    unit: sectors
    
    /dev/sda1 : start=     2048, size=  4194304, Id=82
    /dev/sda2 : start=  5244928, size= 25165824, Id=83, bootable
    /dev/sda3 : start=  4196352, size=  1048576, Id=83
    /dev/sda4 : start= 30410752, size=594728960, Id= 5
    /dev/sda5 : start= 30412800, size= 25165824, Id=83
    /dev/sda6 : start= 55580672, size= 25165824, Id=83
    /dev/sda7 : start= 80748544, size= 25165824, Id=83
    /dev/sda8 : start=332423168, size=292716544, Id=83
    /dev/sda9 : start=105916416, size=104857600, Id=83
    /dev/sda10: start=210776064, size= 25165824, Id=83
    /dev/sda11: start=235943936, size= 25165824, Id=83
    /dev/sda12: start=261111808, size= 25165824, Id=83
    /dev/sda13: start=286279680, size= 25165824, Id=83
    /dev/sda14: start=311447552, size= 10485760, Id=83
    /dev/sda15: start=321935360, size= 10485760, Id=83
    I edited the table to:
    Code:
    # partition table of /dev/sda
    unit: sectors
    
    /dev/sda1 : start=     2048, size=  4194304, Id=82
    /dev/sda3 : start=  5244928, size= 25165824, Id=83, bootable
    /dev/sda2 : start=  4196352, size=  1048576, Id=83
    /dev/sda4 : start= 30410752, size=594728960, Id= 5
    /dev/sda5 : start= 30412800, size= 25165824, Id=83
    /dev/sda6 : start= 55580672, size= 25165824, Id=83
    /dev/sda7 : start= 80748544, size= 25165824, Id=83
    /dev/sda15: start=332423168, size=292716544, Id=83
    /dev/sda14: start=105916416, size=104857600, Id=83
    /dev/sda8 : start=210776064, size= 25165824, Id=83
    /dev/sda9 : start=235943936, size= 25165824, Id=83
    /dev/sda10: start=261111808, size= 25165824, Id=83
    /dev/sda11: start=286279680, size= 25165824, Id=83
    /dev/sda12: start=311447552, size= 10485760, Id=83
    /dev/sda13: start=321935360, size= 10485760, Id=83
    I then attempt to re-write the partition table by using:
    Code:
    sudo swapoff -a
    sudo sfdisk /dev/sda < Desktop/PT2.txt
    It runs, displays lots of errors about the partitions not starting or ending on a cylinder (I partition to MiB) and says it was successful. However nothing changes either before or after a reboot?

    Not that it's relavent but someone will ask...
    I wanted the two largest partitions to be 14 and 15 then everything else in number order. Looking at the GParted image you'd get:
    sda1,2,3,4 (Extended),5,6,7,14,8,9,10,11,12,13,15.
    And to answer the other not relevant question that someone will ask: Because I'm playing in effort to learn and why not?

    Am I doing something wrong or can anyone see anything else that might be causing this issue?
    The only obvious error is the
    Code:
    Warning: Partition [x] does not start at a cylinder boundary
    Warning: Partition [x] does not end at a cylinder boundary
    Warning: Partition x does not end at a cylinder boundary
    But I didn't think we still had to do that when partitioning but are instead advised to "Align to MiB"??

    There is something else; after trying to apply the edited table, at the end there is a message:
    Code:
    If you created or changed a DOS partition, /dev/foo7, say, then use dd(1) to zero the first 512 bytes: [shows code]
    I didn't want to do this without checking with you guys first that this applies to me.
    Attached Images Attached Images
    Last edited by Mr_JMM; November 17th, 2012 at 05:54 PM.
    Linux is not windows // Ubuntu (Quantal:12.10) Guide
    Use descriptive thread titles // Linux... is... not... windows // OSX... is... not... Linux

  2. #2
    Join Date
    Sep 2007
    Location
    England / U.S.
    Beans
    277
    Distro
    Ubuntu 12.10 Quantal Quetzal

    Re: Using sfdisk to change partitions numbers, changes not being applied

    Bump
    Linux is not windows // Ubuntu (Quantal:12.10) Guide
    Use descriptive thread titles // Linux... is... not... windows // OSX... is... not... Linux

  3. #3
    Join Date
    Jun 2009
    Location
    Chicago Suburbs
    Beans
    Hidden!
    Distro
    Ubuntu 12.04 Precise Pangolin

    Re: Using sfdisk to change partitions numbers, changes not being applied

    And why?

    I have not used sfdisk to fix, but have some notes (as usual ) Caljohsmith contributed to bootinfoscript, so he knows lots of details on systems.
    I think you are missing some parameters?

    Using sfdisk to fix partition table problems - not without risk
    http://ubuntuforums.org/showthread.php?t=1192598
    Equivalent sfdisk values would keep the start point and convert the end point via the formula size = end - start + 1.
    Also fdisk -lu shows start & blocks, blocks * 2 also equals size in sectors

    Caljohnsmith using sfdisk to edit partition table from text file
    http://ubuntuforums.org/showthread.php?t=1036600
    http://ubuntuforums.org/showthread.php?t=1038943
    caljohnsmith and meierfra use sfdisk links:
    Exported partition table & reimported to fix with sfdisk.
    http://ubuntuforums.org/showthread.php?t=1591704
    For info on UEFI boot install & repair:
    http://ubuntuforums.org/showthread.php?t=2147295
    Please use Thread Tools above first post to close thread when/if answered completely.




Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •