ext2 vs ext3/4 over eMMC

ext2 vs ext3/4 over eMMC

[Mauro Ziliani]

Hi all.

I working on imx6dlsabresd clone board equiped with eMMC micron (4GB).

I try some boards with my final application. All boards are the equiped 
with same hardware (I hope).


Some board with ext2 kernel tells


EXT2-fs (mmblk2p2): error: ext2_lookup: delete inode referenced: 138049

EXT2-fs (mmblk2p2): error: ext2_lookup: delete inode referenced: 138050

and the file behind the inode gives Input/Output error.


If I format the mmcblk2p2 with ext3 or better with ext4 the lookup error 
no longer occurs (as I can see from some test)


Where is the problem?

Is it an hardware problem, that is solved by the journaling of ext3/4=?

Or ext2 has some kind of "misunderstaing" with eMMC?


Best regards,

   MZ

Re: ext2 vs ext3/4 over eMMC

[Marc Ferland]

On Tue, Jun 26, 2018 at 6:27 AM, Mauro Ziliani <mauro@faresoftware.it> wrote:
> Hi all.
>
> I working on imx6dlsabresd clone board equiped with eMMC micron (4GB).
>
> I try some boards with my final application. All boards are the equiped with
> same hardware (I hope).
>
>
> Some board with ext2 kernel tells
>
>
> EXT2-fs (mmblk2p2): error: ext2_lookup: delete inode referenced: 138049
>
> EXT2-fs (mmblk2p2): error: ext2_lookup: delete inode referenced: 138050
>
> and the file behind the inode gives Input/Output error.
>
>
> If I format the mmcblk2p2 with ext3 or better with ext4 the lookup error no
> longer occurs (as I can see from some test)
>
>
> Where is the problem?
>
> Is it an hardware problem, that is solved by the journaling of ext3/4=?
>
> Or ext2 has some kind of "misunderstaing" with eMMC?

Typically ext3 or ext4 will help you recover from system crashes and
power failures because they use a journal to keep track of changes not
yet committed to the media . Ext2 does not have that capacity.

It is not a hardware issue.

Nice review of filesystems wrt embedded systems:

https://elinux.org/images/archive/0/02/20150326011053%21Filesystem_Considerations_for_Embedded_Devices.pdf

Marc

Re: ext2 vs ext3/4 over eMMC

[Mauro Ziliani]

Thanks for your answer.

But if the hardware works well and the system is powered off correctly 
(the partition is correcly umounted), why with ext2 I get corruption and 
with ext3/4 no?

There is some operation made by ext2 which is not fully compatible with 
eMMC?

MZ


Il 26/06/2018 15:08, Marc Ferland ha scritto:
> On Tue, Jun 26, 2018 at 6:27 AM, Mauro Ziliani <mauro@faresoftware.it> wrote:
>> Hi all.
>>
>> I working on imx6dlsabresd clone board equiped with eMMC micron (4GB).
>>
>> I try some boards with my final application. All boards are the equiped with
>> same hardware (I hope).
>>
>>
>> Some board with ext2 kernel tells
>>
>>
>> EXT2-fs (mmblk2p2): error: ext2_lookup: delete inode referenced: 138049
>>
>> EXT2-fs (mmblk2p2): error: ext2_lookup: delete inode referenced: 138050
>>
>> and the file behind the inode gives Input/Output error.
>>
>>
>> If I format the mmcblk2p2 with ext3 or better with ext4 the lookup error no
>> longer occurs (as I can see from some test)
>>
>>
>> Where is the problem?
>>
>> Is it an hardware problem, that is solved by the journaling of ext3/4=?
>>
>> Or ext2 has some kind of "misunderstaing" with eMMC?
> Typically ext3 or ext4 will help you recover from system crashes and
> power failures because they use a journal to keep track of changes not
> yet committed to the media . Ext2 does not have that capacity.
>
> It is not a hardware issue.
>
> Nice review of filesystems wrt embedded systems:
>
> https://elinux.org/images/archive/0/02/20150326011053%21Filesystem_Considerations_for_Embedded_Devices.pdf
>
> Marc