Re: Regarding UBI scalability

Artem Bityutskiy
2009-02-04T07:45:59Z

On Tue, 2009-02-03 at 12:13 +0100, Corentin Chary wrote:
> On Tue, Feb 3, 2009 at 11:46 AM, Artem Bityutskiy
> <dedekind@infradead.org> wrote:
> > On Tue, 2009-02-03 at 00:44 +0100, Corentin Chary wrote:
> >> I was wondering how it is possible to get atomic operations using such tables ?
> >> The first thing that come to my mind is TFAT (two tables, one for
> >> operation in progress,
> >> the other considered as always "valid"). But I'm not sure it' the good
> >> way to do such a thing.
> >
> > Journal + commit mechanisms should allow doing this.
>
> I'm asking some other questions, because in UFFS we are working on
> something like that, but not for UBI2. But if I can help for UBI2,
> I'll.
>
> A journal node, would probably take less than 16 B. With min_io_size
> >= 512 B (sometime 2KB), a journal for map/unmap operation will take
> some time before being written.

Well, to guarantee integrity, I do not see any other solution but doing
2x2KiB writes on 2KiB-page NAND: start update (1), (write the LEB
somewhere), end update (2), (erase the old PEB). That's the price you
pay.

--
Best regards,
Artem Bityutskiy (Битюцкий Артём)