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Thread: Partitioning

  1. #1
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    Partitioning

    I installed iso20200325 and iso20200326 on an older computer without UEFI support with one SSD and one HD.
    I used the Erase Disk method and expected to get partition 1 for the boot files and partition 2 for the system.
    However I got Partition 1 för the boot files, an Extended Partition 2 and Partition 5 for the system. I have never seen this before and the EFI folder is empty.
    Is Ubiquity changed to give this kind of strange partitioning?

  2. #2
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    Re: Partitioning

    It looks like you installed in UEFI boot mode to a MBR partitioned drive.
    Post these, I expect parted to say MSDOS/MBR and fstab to show mount of ESP:
    sudo parted -l
    cat /etc/fstab

    You do not see files in ESP.
    If you look at fstab you will see the mount of your ESP. It will have permissions of umask=0077 where before 14.04 it used defaults. When you run Boot-Repair it also changes to defaults, so it can edit the ESP files.
    I also change to defaults, but that may be a security issue and may change back to 0077.
    For more info on UEFI boot install & repair - Regularly Updated :
    http://ubuntuforums.org/showthread.php?t=2147295
    Please use Thread Tools above first post to change to [Solved] when/if answered completely.

  3. #3
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    Re: Partitioning

    Perhaps I haven't noticed this before, but why doesn't an installation with "Erase disk" create a "better" partitioning.
    I had W10 installed on this computer earlier. Perhaps that's the reason why /boot/efi is formatted as vfat.
    I will check two things and see what's happening
    - Install with an earlier iso
    - Format the disk before installation
    Code:
    p-i@pi-GA-990FXA-UD3:~$ sudo parted -l
    [sudo] password for p-i: 
    Model: ATA KINGSTON SV300S3 (scsi)
    Disk /dev/sda: 120GB
    Sector size (logical/physical): 512B/512B
    Partition Table: msdos
    Disk Flags: 
    Number  Start   End    Size   Type      File system  Flags
     1      1049kB  538MB  537MB  primary   fat32        boot
     2      539MB   120GB  119GB  extended
     5      539MB   120GB  119GB  logical   ext4
    Model: ATA WDC WD6400AAKS-0 (scsi)
    Disk /dev/sdb: 640GB
    Sector size (logical/physical): 512B/512B
    Partition Table: msdos
    Disk Flags: 
    Number  Start   End    Size   Type     File system  Flags
     1      1049kB  640GB  640GB  primary  ext4         boot
    
    p-i@pi-GA-990FXA-UD3:~$ cat /etc/fstab
    # /etc/fstab: static file system information.
    #
    # Use 'blkid' to print the universally unique identifier for a
    # device; this may be used with UUID= as a more robust way to name devices
    # that works even if disks are added and removed. See fstab(5).
    #
    # <file system> <mount point>   <type>  <options>       <dump>  <pass>
    # / was on /dev/sda5 during installation
    UUID=c0acf1e4-0b1e-49b0-824e-e9db9ca1c156 /               ext4    errors=remount-ro 0       1
    # /boot/efi was on /dev/sda1 during installation
    UUID=441D-FD7E  /boot/efi       vfat    umask=0077      0       1
    /swapfile                                 none            swap    sw              0       0
    p-i@pi-GA-990FXA-UD3:~$

  4. #4
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    Re: Partitioning

    You have UEFI install to MBR(msdos) partitioned drive.

    Much better to use gpt.
    Gparted still defaults to using MBR on smaller drives, you have to change to gpt if formatting in advance.

    Installer must have seen MBR, otherwise I believe it would have used gpt with UEFI as that is the recommendation.
    Windows will only install in UEFI mode to gpt drives.

    PT Advantages (older 2010 but still valid) see post#2 by srs5694:
    http://ubuntuforums.org/showthread.php?t=1457901
    https://wiki.archlinux.org/index.php...antages_of_GPT
    http://en.wikipedia.org/wiki/Unified...ware_Interface

    Gigabyte GA-990FXA-UD3 and 64bit Xubuntu 16.04 LTS install
    https://ubuntuforums.org/showthread.php?t=2370503
    For more info on UEFI boot install & repair - Regularly Updated :
    http://ubuntuforums.org/showthread.php?t=2147295
    Please use Thread Tools above first post to change to [Solved] when/if answered completely.

  5. #5
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    Re: Partitioning

    Made some test.
    Formated the ssd with Disks to "No partitioning (Empty) and started an installation. No change still made an extended partition.
    Formated with GPT and Ubiquity still made an extended partition.
    Continued the installation and in this case the installation crashed.
    Made a new USB installation device with iso20200327 which also crashed at installation. Got the message about already known bug.
    There is however an MBR on the HDD, but does this have any impact?

  6. #6
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    Re: Partitioning

    The gpt partitioning has a protective MBR. That has one entry for gpt for entire drive if less than 2TiB, or is 2TiB, so old MBR based tools do not automatically assume drive is empty and partition/format it.

    What does this show?
    sudo gdisk -l /dev/sda

    I have always partitioned in advance with gpt & usually several partitions and never have had an issue. But I use gparted as Disks has in past had some issues. I do use Disks only to label partitions when I forget to label using gparted.
    For more info on UEFI boot install & repair - Regularly Updated :
    http://ubuntuforums.org/showthread.php?t=2147295
    Please use Thread Tools above first post to change to [Solved] when/if answered completely.

  7. #7
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    Re: Partitioning

    Code:
    p-i@pi-GA-990FXA-UD3:~$ sudo gdisk -l /dev/sda
    [sudo] password for p-i: 
    GPT fdisk (gdisk) version 1.0.5
    
    Partition table scan:
      MBR: MBR only
      BSD: not present
      APM: not present
      GPT: not present
    
    
    ***************************************************************
    Found invalid GPT and valid MBR; converting MBR to GPT format
    in memory. 
    ***************************************************************
    
    Disk /dev/sda: 234441648 sectors, 111.8 GiB
    Model: KINGSTON SV300S3
    Sector size (logical/physical): 512/512 bytes
    Disk identifier (GUID): 91B70B2A-F1AD-498C-8AB6-0556644E4A2C
    Partition table holds up to 128 entries
    Main partition table begins at sector 2 and ends at sector 33
    First usable sector is 34, last usable sector is 234441614
    Partitions will be aligned on 2048-sector boundaries
    Total free space is 4973 sectors (2.4 MiB)
    
    Number  Start (sector)    End (sector)  Size       Code  Name
       1            2048         1050623   512.0 MiB   0700  Microsoft basic data
       5         1052672       234440703   111.3 GiB   8300  Linux filesystem
    p-i@pi-GA-990FXA-UD3:~$
    As you suspected Disks didn't partitioned sda properly.
    Anyhow I don't understand why Ubiquity don't prepare the disk correctly when "Erase disk" is used.

    Made a new iso, booted and used gparted to clean sda. Started an install, but sda was still partitioned with an extended partition.
    Checked sda and there is still a protective MBR.
    Code:
    ubuntu@ubuntu:~$ sudo gdisk -l /dev/sda
    GPT fdisk (gdisk) version 1.0.5
    
    Partition table scan:
      MBR: protective
      BSD: not present
      APM: not present
      GPT: present
    
    Found valid GPT with protective MBR; using GPT.
    Disk /dev/sda: 234441648 sectors, 111.8 GiB
    Model: KINGSTON SV300S3
    Sector size (logical/physical): 512/512 bytes
    Disk identifier (GUID): 400D9BD0-9398-43E5-9FC4-A86EF5C06992
    Partition table holds up to 128 entries
    Main partition table begins at sector 2 and ends at sector 33
    First usable sector is 34, last usable sector is 234441614
    Partitions will be aligned on 2048-sector boundaries
    Total free space is 234441581 sectors (111.8 GiB)
    
    Number  Start (sector)    End (sector)  Size       Code  Name
    ubuntu@ubuntu:~$
    Last edited by P-I H; March 29th, 2020 at 09:30 AM.

  8. #8
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    Re: Partitioning

    What would happen if you wipe the whole device (overwrite it with zeros for example with mkusb)? Then there should be no traces on the drive to tempt the installer to create an MSDOS partition table. So if that still happens, it is the default behaviour, at least in this older computer without UEFI support.

    By the way, maybe it is worth testing that in a computer where you can select both boot modes. If you do that, is there a difference between the partition table created in UEFI mode and BIOS mode (alias CSM alias legacy mode)?

  9. #9
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    Re: Partitioning

    Found valid GPT with protective MBR;
    That says sda is gpt partitioned.
    For more info on UEFI boot install & repair - Regularly Updated :
    http://ubuntuforums.org/showthread.php?t=2147295
    Please use Thread Tools above first post to change to [Solved] when/if answered completely.

  10. #10
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    Re: Partitioning

    Done that with Disks and this cleaned the disk.
    sudo gdisk -l /dev/sda gave the result
    MBR: not present
    BSD: not present
    APM: not present
    GPT: not present
    However even now an extended partition was created when "Erase Disk" was used.
    Tried with something else and selected the whole disk. This worked, got one partition which included a MBR.
    Booted with the USB again. Used gparted this time, made a GPT partition table and a fat32 partition. Installed with the "Something Else" method. This time I got /dev/sda1 fat32 and /dev/sda2 ext4.
    However Ubiquity didn't use /dev/sda1, perhaps because I didn't set any flags.
    It seems to be quite complicated to manage the boot records. In case you have a dual boot with W7 and Ubuntu and want to reinstall Ubuntu, the protective MBR is needed. In case you want to install W10 and Ubuntu in UEFI mode I suppose you need to overwrite the disk with zeros and this will take some time.
    The system I used have a HDD with Ubuntu 19.10 installed in legacy mode, that may also have some impact.

    This is information from the actual system
    Last edited by P-I H; March 29th, 2020 at 03:17 PM.

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