RE: RFC: detect and manage power cut on MLC NAND (linux-mtd Digest, Vol 144, Issue 70)

["Jeff Lauruhn (jlauruhn)" <jlauruhn@micron.com>]

Disturb is a block level affect, but in operation data is often layout in continuous blocks, so if one block is seeing a lot of reads or P/E cycles, there's a high probability the blocks around it are also seeing very similar read and P/E patterns. 



Jeff Lauruhn
NAND Application Engineer
Embedded Business Unit



-----Original Message-----
From: Richard Weinberger [mailto:richard@nod.at] 
Sent: Wednesday, March 18, 2015 5:07 AM
To: Boris Brezillon; Andrea Marson
Cc: Jeff Lauruhn (jlauruhn); linux-mtd@lists.infradead.org; Andrea Scian; dedekind1@gmail.com
Subject: Re: RFC: detect and manage power cut on MLC NAND (linux-mtd Digest, Vol 144, Issue 70)

Am 18.03.2015 um 10:06 schrieb Boris Brezillon:
>> 1) IIUC read/program disturb effects exhibit at block level.
>> In a typical embedded linux systems there are software parts - 
>> bootloader, kernel image etc. - that virtually are never changed 
>> (almost
>> ...) but are read many times. Other parts - application libraries, 
>> log files etc. - are read and wrote many times instead.
>> If these two kinds of software are stored in different MTD partitions 
>> - ket's say partition A for bootloader, kernel etc. and partition B 
>> for application libraries, log files etc. - can we say that 
>> read/write operations performed on partition B have no disturb effects on partition A?
> 
> AFAIK, read/write disturb effects only occur on pages of the same 
> block, so we shouldn't see bitflips on partition A caused by 
> read/write on partition B.

I already saw corruptions on nearby blocks but I'm not sure if really plain read disturb was the root cause as this NAND chips showed in general funny symptoms.

Jeff, can you tell us more?

Thanks,
//richard