On 08 May 2012 22:19:00 +0200
Hullen@t-online.de (Helmut Hullen) wrote:

> What I still hope (may be it's impossible): when 1 disk/partition fails,  
> then the contents of the other disks is "somehow" restorable. And not  
> irreproducable.

You should look for file/directory-level tree merging, e.g. this FUSE based
virtual FS: 

  https://romanrm.ru/en/mhddfs

Or various other unionfs'es, some of which are kernel-based.

Regarding btrfs, AFAIK even "btrfs -d single" suggested above works not "per
file", but per allocation extent, so in case of one disk failure you will lose
random *parts* (extents) of random files, which in effect could mean no file
in your whole file system will remain undamaged.

-- 
With respect,
Roman

~~~~~~~~~~~~~~~~~~~~~~~~~~~
"Stallman had a printer,
with code he could not see.
So he began to tinker,
and set the software free."