Re: ubifs wear leveling across entire device

[twebb <taliaferro62@gmail.com>]

>
> Wear-levelling occurs within a single UBI device which is generally
> a single MTD partition.
>
> You need 1 MTD partition and 1 UBI device with 3 volumes.  Make the
> 3 volumes total less than the whole UBI device and you can add a 4th
> volume later.
>

If I make 1 MTD partition and 1 corresponding UBI device, should (can)
it include areas that will never be accessed via UBI-aware tools?  For
example, is it safe to have on a 4GB physical device a single 4GB MTD
partition with a single corresponding UBI device, but only 3GB of the
4GB device contain N UBI volumes only accessed via appropriate UBI
user-space (or u-boot) tools while the remaining 1GB of the 4GB is
accessed with mtd-utils?

There are two reasons for this approach:
1 - to (hopefully) get the benefits of wear leveling across the entire
physical device (though I think this may not work in the scenario I've
described)
2 - to allow access to a portion of the flash by non-UBI aware code

I assume the alternative (w/o the benefit of wear leveling across the
entire device) is to define 2 MTD partitions: 1 for "non-UBI" access
and 1 for a single UBI device with multiple UBI volumes?

Thanks,
twebb