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Thread: Partitioning Flash

  1. #1
    Join Date
    Oct 2013
    Beans
    2

    Partitioning Flash

    I'm trying to partition a 16GB microsd to have its original FAT32 partition and add a ~2GB ext3 partition. Ability to symlink with internal Android storage is the goal.

    Some parted output of the virgin microsd...
    Code:
    Disk /dev/mmcblk0: 15.9 GB, 15931539456 bytes
    255 heads, 63 sectors/track, 1936 cylinders, total 31116288 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: 0x00000000
    
            Device Boot      Start         End      Blocks   Id  System
    /dev/mmcblk0p1            8192    31116287    15554048    c  W95 FAT32 (LBA)
    
    Command (m for help): u
    Changing display/entry units to cylinders (DEPRECATED!)
    
    Command (m for help): p   
    
    Disk /dev/mmcblk0: 15.9 GB, 15931539456 bytes
    255 heads, 63 sectors/track, 1936 cylinders
    Units = cylinders of 16065 * 512 = 8225280 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Disk identifier: 0x00000000
    
            Device Boot      Start         End      Blocks   Id  System
    /dev/mmcblk0p1               1        1937    15554048    c  W95 FAT32 (LBA)
    I'd like to use GParted for simplicity, but when I try to resize the FAT32 by leaving the Free Space Preceding the same and just reduce the size, I have a problem:

    It doubles the size of the Free Space Preceding. This ticks me off. Didn't the microsd designers choose a certain Start for a reason? What's the best recommendation for achieving my goal? Thanks!

  2. #2
    Join Date
    Jun 2009
    Location
    SW Forida
    Beans
    Hidden!
    Distro
    Ubuntu 16.04 Xenial Xerus

    Re: Partitioning Flash

    You are displaying in cylinders. SSD & flash drive so not even have cylinders, but BIOS stopped using cylinders when hard drives went over 8GB many years ago. The use LBA or large block allocation.

    But SSD (and flash?) are block devices and you best read & write entire blocks. If start and size of partition is not on 8 sector boundries you will have issues.

    http://www.ibm.com/developerworks/li...sks/index.html
    Alignment 2048 sectors Advanced Format drives
    http://askubuntu.com/questions/20116...d-using-parted
    Technical details - from 2010 so now newer kernel resolve linux issues
    https://ata.wiki.kernel.org/index.ph..._sector_issues

    Boot loaders like grub also need room after the first sector or MBR for additional boot code. If too small you will get grub install errors.
    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
    Join Date
    Oct 2013
    Beans
    2

    Re: Partitioning Flash

    Thank you Fred!

    I'm also trying to learn about what the Linaro folks are doing...
    http://www.google.com/search?q=linaro+partition+flash
    ...but alas for my particular task here I decided to leave the uSD as FAT32 like from the factory. I'm gonna research this more. Anybody else have some FAT32+ext3 flash partitioning wisdom?

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