5 Replies Latest reply: May 28, 2013 1:02 AM by Catch 22 RSS

    Partition 1 does not end on cylinder boundary

    Catch 22
      As far as I understand, the warning "Partition 1 does not end on cylinder boundary" can be ignored since most hard drives after 1996 use Logical Block Addressing (LBA) and so the physical sector characteristics of a drive are no longer a relevant concern when aligning disk partitions.

      Below is the output of fdisk from default installations of Oracle Linux 6.3 and Oracle Linux 5.8. Both were created under Virtualbox so they have the same "virtual" disk characteristics.

      Oracle Linux 6.3
      <pre>
      # fdisk -lu /dev/sda

      Disk /dev/sda: 21.5 GB, 21474836480 bytes
      255 heads, 63 sectors/track, 2610 cylinders, total 41943040 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: 0x000a2ccf

      Device Boot Start End Blocks Id System
      /dev/sda1 * 2048 1026047 512000 83 Linux
      Partition 1 does not end on cylinder boundary.
      /dev/sda2 1026048 41943039 20458496 8e Linux LVM

      fdisk -v
      fdisk (util-linux-ng 2.17.2)
      </pre>

      Oracle Linux 5.8
      <pre>
      # fdisk -lu /dev/sda

      Disk /dev/sda: 21.4 GB, 21474836480 bytes
      255 heads, 63 sectors/track, 2610 cylinders, total 41943040 sectors
      Units = sectors of 1 * 512 = 512 bytes

      Device Boot Start End Blocks Id System
      /dev/sda1 * 63 208844 104391 83 Linux
      /dev/sda2 208845 41929649 20860402+ 8e Linux LVM

      fdisk -v
      fdisk (util-linux 2.13-pre7)
      </pre>

      As far as I can tell, 6.3 and 5.8 have both partitions with sectors that are not a multiple of 8.

      How can I avoid the message, even if it may just address a cosmetic issue?
        • 1. Re: Partition 1 does not end on cylinder boundary
          Catch 22
          I guess I can answer my question meanwhile.

          Fdisk under RHEL 6 or Oracle Linux 6 has a DOS compatibility mode. It can be turned off (and recommended by the man page) by using the -c parameter.

          <pre>
          fdisk -clu /dev/sda

          Disk /dev/sda: 21.5 GB, 21474836480 bytes
          255 heads, 63 sectors/track, 2610 cylinders, total 41943040 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: 0x000a2ccf

          Device Boot Start End Blocks Id System
          /dev/sda1 * 2048 1026047 512000 83 Linux
          /dev/sda2 1026048 41943039 20458496 8e Linux LVM
          </pre>

          The question might be why such a setting was added or why it not default, but I guess it explains what I experienced.
          • 2. Re: Partition 1 does not end on cylinder boundary
            1011224
            Dude,

            You might want to read this before you made conclusion...

            Cheers,


            Andy

            http://media.netapp.com/documents/tr-3747.pdf
            • 3. Re: Partition 1 does not end on cylinder boundary
              Catch 22
              Are you just sharing some information or why do you think it makes a difference?
              • 4. Re: Partition 1 does not end on cylinder boundary
                alvaromiranda
                I haven't figured how to avoid that warning at all.

                In some installation it does happen, in some other it doesn't

                If I create the partition layout with anaconda, some times the fdisk at os level complain, some time it doesn't.
                • 5. Re: Partition 1 does not end on cylinder boundary
                  Catch 22
                  It's been a while since I looked into the issue, but as far as I remember it is just that particular version of fdisk in RHEL 6 which does not have DOS compatibility mode disabled by default. Using the -c parameter should disable this warning.

                  DOS compatibility mode is obsolete. There is no need for CHS addressing, which was used for very old disks using a floppy disk schema. All modern hard drives use LBA, so the values fdisk uses are going to be translated by the disk anyway to match the actual disk alignment and geometry.