MTD copy on JFFS2

MTD copy on JFFS2

[Sriram Neelakandan Iyer]

hi list,
i have 2 jffs2 partitions(over mtd) used for storing
config files.
I need to copy all the files from one partition to
another, and the destination mtd partition is larger
than the source mtd partition.(i cannot mount the
second partition as jffs2 before the data is copied)

As of now i run mkfs.jffs2 over the source jffs2
directory and copy to ramfs and then erase the
destination partition and i do a mtd-write over the
destination partition.

But mkfs.jffs2 needs libz and both of them occupy
about 87K of space.

So i plan to do a plain mtd-copy ,i.e 
1. first unmount source jffs2,
2. read over the source mtd-char-device and 
3. dump it back to the second mtd-partition. 

Will jffs2 be able to mount the second partition
without trouble?  (or) must i do a mkfs.jffs2 always
to have a jffs2 mountable partition.

regards
sriram.


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Re: MTD copy on JFFS2

[Kenneth Johansson]

On Tue, 2002-10-01 at 15:12, Sriram Neelakandan Iyer wrote:
> hi list,
> i have 2 jffs2 partitions(over mtd) used for storing
> config files.
> I need to copy all the files from one partition to
> another, and the destination mtd partition is larger
> than the source mtd partition.(i cannot mount the
> second partition as jffs2 before the data is copied)

So what you want is to change the partition layout on a live system and
that is not possible as the same flash block would for a period end up
in two partitions.

> But mkfs.jffs2 needs libz and both of them occupy
> about 87K of space.
> 
> So i plan to do a plain mtd-copy ,i.e 
> 1. first unmount source jffs2,
> 2. read over the source mtd-char-device and 
> 3. dump it back to the second mtd-partition. 
> 
> Will jffs2 be able to mount the second partition
> without trouble?  (or) must i do a mkfs.jffs2 always
> to have a jffs2 mountable partition.
> 
> regards
> sriram.

Could work. but why not.

1. copy from old partition to ramdisk
2. change to new partition layout 
3. erase and mount new partition
4. copy files from ramdisk to new partition.


-- 
Kenneth Johansson	
Ericsson AB                       Tel: +46 8 404 71 83
Borgafjordsgatan 9                Fax: +46 8 404 72 72
164 80 Stockholm                  kenneth.johansson@etx.ericsson.se

Re: MTD copy on JFFS2

[Jörn Engel]

On Tue, 1 October 2002 06:12:21 -0700, Sriram Neelakandan Iyer wrote:
> i have 2 jffs2 partitions(over mtd) used for storing
> config files.
> I need to copy all the files from one partition to
> another, and the destination mtd partition is larger
> than the source mtd partition.(i cannot mount the
> second partition as jffs2 before the data is copied)
> 
> As of now i run mkfs.jffs2 over the source jffs2
> directory and copy to ramfs and then erase the
> destination partition and i do a mtd-write over the
> destination partition.
> 
> But mkfs.jffs2 needs libz and both of them occupy
> about 87K of space.
> 
> So i plan to do a plain mtd-copy ,i.e 
> 1. first unmount source jffs2,
> 2. read over the source mtd-char-device and 
> 3. dump it back to the second mtd-partition. 

Should work, as long as both partitions have the same erase block
size, the target partition is not smaller and was erased before 3.

> Will jffs2 be able to mount the second partition
> without trouble?

On first mount you will get some messages about missing erase markers,
jffs2 will erase all new blocks. About as dangerous as a collision in
ethernet. :)

Jörn

-- 
Good warriors cause others to come to them and do not go to others.
-- Sun Tzu