linux-ext4 - Question about data integrity on SD cards

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Date:	Wed, 09 Jul 2014 13:17:25 +0100
From:	Grzegorz Sikorski <g.sikorski@...vatek.com>
To:	linux-ext4@...r.kernel.org
Subject: Question about data integrity on SD cards

Hi,

In our project we use SQLite3 database on EXT4 filesystem partition on 
microSD card. On unexpected power failure/system crash or just hardware 
reset, we observe occasional database corruption. SQLite3 developers 
claim their part is free of risk of database corruption, as long as 
fsync call is doing it's job properly. We tried several SD cards, 
including industrial grade which should have proper firmware (at least 
their manufacturers say there is no risk of data corruption on power 
loss). We tried several different mount settings and after some reading 
we found, that the safest (and slowest) option (that should never fail, 
as far as we understand) would be like:
rw,relatime,barrier=1,journal_checksum,nodelalloc,data=journal,usrquota
In spite of all that, we still observe random database corruption on 
power-down/reset. Can you confirm there is no problem in EXT4 filesystem?

Best regards,
Greg

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