Re: "Unformat" a ReiserFS partition : a testimony :-)

[Manuel Krause <manuel.krause@mb.tu-ilmenau.de>]

On 03/25/2003 01:16 AM, Yury Umanets wrote:
> Nicolas Vanderavero wrote:
> 
>> Hello,
> 
> Hello Nicolas,
> 
>> while reinstalling a Debian on a new hard drive, I made the mistake to 
>> format in reiserfs my good old /home which was on /dev/sda7 instead of 
>> formatting the new /dev/hda7. Gasp ! Eight gigabytes lost ...
>>
>> Or ... maybe it was not totally lost :-) I immediately made a dump of 
>> the partition with 'dd' and started grepping some known text on it. It 
>> seemed that no data was really lost. I didn't know what to do. So I 
>> read the man pages and found the reiserfsck command quite interesting :-)
> 
> You have lost the super block and probably old root node. I said 
> "probably" because it might be not used in teh time you did format.

Can you be more clear on this? In which cases does SB get used? Or, how 
would this change Nicholas scenario in practical use? E.g. would a blank 
mount (just mount+umount) change the story so that the partition would 
not be recoverable?

>>
>> Ok, I am a total newbie to filesystems and to ReiserFS. So maybe it 
>> will sound trivial to you, but just in case it happens to anyone else, 
>> I just wanted to say that running a reiserfsck --rebuild-tree -S on my 
>> partition was enough to unformat it. I ended up with some file in 
>> lost+found, but a 'file *' is enough to discover what they are. 
> 
> The first thing you should do in cases like this is to make backup. I 
> hope you'll find eight gigabytes for that. Now you may feel free to do 
> anything with you old partition. Then you should to do --rebuild-sb and 
> try to fsck the partition with --check key. Then follow to fsck sugestions.
> 
> These should be enought for getting you partition back.
> 
>> So, maybe it would be usefull to add an entry in the "Example of 
>> using" section of the man page of reiserfsck, saying something like : 
>> "If you reformatted by mistake a reiserFS partition, you can try to 
>> unformat it by running reiserfsck --rebuild-tree -S on it". 
> 
> Sounds good. Probably Vitaly should consider about that for including it 
> in the next fsck -pre.
>>
>> Anyway, thank you for developing this filesystem.
>> Nicolas Vanderavero.
>>
> P.S. Please read http://www.namesys.com/support.html. Can you as for 
> support?

BTW, I think he found and published a new "feature" (that many would 
like to have in handy in those cases!) and did *not* ask for support. 
Shouldn't you pay him 25$, now?! ;-))

Thanks and best regards,

Manuel