Re: Linux 3.1-rc7

From: Linus Torvalds
Date: Wed Sep 28 2011 - 13:00:12 EST


On Wed, Sep 28, 2011 at 9:38 AM, Arnaud Lacombe <lacombar@xxxxxxxxx> wrote:
>
> At some point I did not trust the internal disk, but SMART tests
> (`short', `'long', `conveyance') passed successfully. I'd assume that
> a bad cable issue between the USB adapter and the disk would be caught
> by the UDMA_CRC_Error_Count counter (it already did), and would be
> somehow truly random. I'm not sure if USB do any kind of data checksum
> between the host and the device. I'd assume so.

I forget what the exact physical level rules are, I wouldn't really
expect all devices to necessarily even check the checksums. There's
some real crap out there.

Iirc, the common USB packet size is 512 bytes, so your corruption
pattern could match that "end of a packet" kind of rule (especially
with the header to specify where the write goes). I dunno. Hardware
problems can be a nasty nasty issue to debug.

Linus
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