Stable File System for embedded product

Mark Hatle fray at
Tue Jan 20 08:00:10 EST 2004

Just from the FHS perspective (the file system standard for Linux)

everything on linux can (and should be) read-only mounted, with the
following exceptions:

   /etc/mtab -- It can be a symlink to /proc/mounts (or a link to a
writable location)

   /tmp  -- mount as a tmpfs (or link to /var/tmp)
   /var  -- mount again as a tmpfs, or a read-write storage

Of course each distribution varies and applications, distributions, etc
have bugs when it comes to FHS compliance..  but this should be the
end-goal for all systems to be standards based.

(For my own systems, usually I have /etc on a read-write capable disk..
but mount read-only..  /etc/mtab is a symlink to /proc/mounts, /tmp is a
symlink to /var/tmp.  /var/tmp is tmpfs.. the rest of var is either
tmpfs or a read-write disk depending on the application.)


Rod Boyce wrote:
> I would much more strongly suggest not mounting this partition
> read-write as this is most likely what is corrupting the partition also
> try noatime as well.  /etc is required for boot up so I would suggest
> changing the way you use /etc.  We have soft links to another location
> on another file system and keep /etc combined with the root file system.
> Upwards of 10K power cycles can't be wrong.
> Rod
>>-----Original Message-----
>>From: Alex Zeffertt [mailto:ajz at]
>>Sent: Monday, 19 January 2004 11:04 p.m.
>>To: S. Hebbar
>>Cc: linuxppc-embedded at
>>Subject: Re: Stable File System for embedded product
>>Are you using a flash device (i.e. /dev/mtdblockN) for /etc?  If so,
>>then I would recommend JFFS for this partition.  JFFS2 is (supposedly)
>>more reliable, but we have found that you can't fit it on a flash
>>partition of only 4 flash sectors since it needs more than that for
>>If it's not flash then maybe you should consider ext3 - a journalling
>>extension to ext2.
>>On Mon, 2004-01-19 at 06:23, S. Hebbar wrote:
>>>I am trying to find which file system is the best for
>>>/etc partition on an embedded linux platform.
>>>I am using the following file systems for linux & rootfs:-
>>>Linux: CramFS (linux 2.4.20 denx) (read-only)
>>>RootFS: CramFS  (read-only)
>>>At the moment, I am using ext2 partition for /etc (read-write)
>>>But, 1 out of  4 power-cycles of the board corrupts the
>>>/etc partition.
>>>Any information related to the above topic is
>>>grately appreciated.
>>>S. Hebbar.

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