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  • How do you wipe a UBI filesystem?

    From Grant Edwards@21:1/5 to All on Wed Feb 5 19:30:04 2025
    Pretend I've got an MTD partition attached as a UBI device.

    That UBI device contains a couple differen UBI volumes.

    In one of those volumes is a UBIFS filesystem that has a bunch of
    files in it.

    I've done some googling, but all of the answers are "use
    ubiformat". That will wipe the whole device. I just want to
    re-initialize one ubifs filesytem in one volume -- not the whole
    ubi device.

    How do I wipe that filesystem (set it back to empty). Do I need to
    create an empty ubifs "image" file using mkfs.ubifs and then use
    ubiupdatevol to write that image to the volume?

    Isn't there a simpler way?

    --
    Grant

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Grant Edwards@21:1/5 to Grant Edwards on Wed Feb 5 21:15:32 2025
    On 2025-02-05, Grant Edwards <[email protected]d> wrote:
    Pretend I've got an MTD partition attached as a UBI device.

    That UBI device contains a couple differen UBI volumes.

    In one of those volumes is a UBIFS filesystem that has a bunch of
    files in it.

    I've done some googling, but all of the answers are "use
    ubiformat". That will wipe the whole device. I just want to
    re-initialize one ubifs filesytem in one volume -- not the whole
    ubi device.

    How do I wipe that filesystem (set it back to empty). Do I need to
    create an empty ubifs "image" file using mkfs.ubifs and then use
    ubiupdatevol to write that image to the volume?

    Isn't there a simpler way?

    I've figured out two other ways to do it:

    ubiupdatevol -t /dev/ubiX_Y
    mount -t ubifs /dev/ubiX:volname /mnt/point

    That works, but apparently that erases every block in the
    volume. That's a lot of unecessary wear. Surely you can "empty" the
    filesystem without erasing every block in the volume (when probably
    90% of the blocks have never been written).

    Another option:

    ubirmvol /dev/ubiX -N volname
    umimkvol /dev/ubiX -N volname -m
    mount -t ubifs /dev/ubiX:volname /mnt/point

    That too seems to work, but modifying the devices volume table/list
    seems a bit risky compared to simply re-initializing the filesystem
    inside an existing volume.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From chrisq@21:1/5 to Grant Edwards on Wed Feb 12 15:03:06 2025
    On 2/5/25 19:30, Grant Edwards wrote:
    Pretend I've got an MTD partition attached as a UBI device.

    That UBI device contains a couple differen UBI volumes.

    In one of those volumes is a UBIFS filesystem that has a bunch of
    files in it.

    I've done some googling, but all of the answers are "use
    ubiformat". That will wipe the whole device. I just want to
    re-initialize one ubifs filesytem in one volume -- not the whole
    ubi device.

    How do I wipe that filesystem (set it back to empty). Do I need to
    create an empty ubifs "image" file using mkfs.ubifs and then use
    ubiupdatevol to write that image to the volume?

    Isn't there a simpler way?


    Try a search:

    "ubi file system utilities Linux"

    Which may help, third entry down ?.

    Chris

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Grant Edwards@21:1/5 to chrisq on Wed Feb 12 18:03:07 2025
    On 2025-02-12, chrisq <[email protected]> wrote:
    On 2/5/25 19:30, Grant Edwards wrote:
    Pretend I've got an MTD partition attached as a UBI device.

    That UBI device contains a couple differen UBI volumes.

    In one of those volumes is a UBIFS filesystem that has a bunch of
    files in it.

    I've done some googling, but all of the answers are "use
    ubiformat". That will wipe the whole device. I just want to
    re-initialize one ubifs filesytem in one volume -- not the whole
    ubi device.

    How do I wipe that filesystem (set it back to empty). Do I need to
    create an empty ubifs "image" file using mkfs.ubifs and then use
    ubiupdatevol to write that image to the volume?

    Isn't there a simpler way?

    Try a search:

    "ubi file system utilities Linux"

    Which may help, third entry down ?.

    The answer is 'ubiupdatevol -t' (bracketed by umount/mount commands).

    I had figured out that command worked, but one tutorial/blog I found
    stated that it erased every block in the volume. The way it was
    described it sounded like doing a 'ubiupdatevol -t' on a 20MB volume
    would erase 20MB of flash -- even if that volume contained a
    filesystem with only a few small files in it.

    So I was reluctant to use it because of the uneccessary wear on the
    flash when used on volumes that were mostly empty. It turns out that
    blog was wrong/misleading.

    The truncate operation doesn't erase any blocks. It _unmaps_ any
    _programmed_ blocks that are currently in use in the volume. Those
    blocks will later be erased and put back in the "free" pool during
    garbage collection. No blocks are erased either unnecessarily or by
    the command itself.

    --
    Grant

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)