Doubts about File Systems on FIASCO on ARM (Cortex-A15)

Maria Soler m.soler at virtualopensystems.com
Thu Jul 3 09:25:30 CEST 2014


Hi again,

Thanks to all for your answers. After further investigation I don't
seem to actually need disk access/a file system by now, so I'll leave
this thread of work for the moment.

Thanks again,
María.

On Fri, Jun 20, 2014 at 12:02 PM, Martin Schröder
<martin.schroeder at openlimit.com> wrote:
> Am 19.06.2014 18:06, schrieb Jorge Ventura:
>
>> This is a good direction. I forgot that, in reality we need two drivers,
>> one for a block device and another one for the filesystem itself.
>>
>
> The two drivers are not sufficient if the underlying hardware is some sort
> of bare flash devices (NOR, NAND) and you use a traditional file system. The
> number of erase cycles of an individual block is limited. So writes of
> frequently written blocks (directory, file allocation table) need to be
> evenly spread over the device to avoid a premature death of vital blocks.
> This is the so called wear levelling which is an additional driver in
> between the block device driver and the file system driver. Or you use a
> file systems which incorporates wear levelling (JFFS2, UBIFS).
>
> The two drivers are sufficient only if the underlying hardware is an
> intelligent device like a hard disk, SSD, SD card or USB Stick. Such devices
> have their own controller performing wear levelling itself.
>
>
> Martin
>
>
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