linux-kernel - Re: [RFC/PATCH 0/1] ubi: Add ubiblock driver

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Date:	Fri, 30 Nov 2012 13:25:49 +0200
From:	Artem Bityutskiy <dedekind1@...il.com>
To:	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
Cc:	Ezequiel Garcia <elezegarcia@...il.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-mtd@...ts.infradead.org,
	David Woodhouse <dwmw2@...radead.org>,
	Tim Bird <tim.bird@...sony.com>,
	Michael Opdenacker <michael.opdenacker@...e-electrons.com>
Subject: Re: [RFC/PATCH 0/1] ubi: Add ubiblock driver

On Wed, 2012-11-21 at 11:00 +0100, Thomas Petazzoni wrote:
> While I think the original ubiblk that was read-only made sense to
> allow the usage of read-only filesystems like squashfs, I am not sure
> a
> read/write ubiblock is useful.
> 
> Using a standard block read/write filesystem on top of ubiblock is
> going
> to cause damage to your flash. Even though UBI does wear-leveling,
> your
> standard block read/write filesystem will think it has 512 bytes block
> below him, and will do a crazy number of writes to small blocks. Even
> though you have a one LEB cache, it is going to be defeated quite
> strongly by the small random I/O of the read/write filesystem.

Well, in practice normal file-system do 4K-aligned I/O, without crazy
things, and try to do I/O sequentially.
> 
> I am not sure letting people use read/write block filesystems on top
> of
> flashes, even through UBI, is a good idea. 

Why not?

-- 
Best Regards,
Artem Bityutskiy

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