Re: [dm-devel] [PATCH 0/4] dm verity: add support for error correction

[Mikulas Patocka]

On Fri, 6 Nov 2015, Sami Tolvanen wrote:

> On Fri, Nov 06, 2015 at 08:20:15PM +0100, Zdenek Kabelac wrote:
> > i.e. you have 1G of space - you want to give 250MB as 'redundancy' -
> > so create 4 partition....
> 
> We cannot afford to set aside 25% of read-only partition space for

You can have 20 raid5 legs (with as big chunksizes as possible - so that 
sequential accesses are really sequential when they hit the flash device), 
and that means setting aside only 5%. Or even more legs.

Mikulas

> redundancy on mobile devices, and would rather not impact performance
> any more than dm-verity already does. With error correction we have
> 0.8% space overhead in our use case and no performance degradation if
> the partition is not corrupted.
> 
> Sami
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