Re: I've done a very bad mistake

Re: I've done a very bad mistake

[Andreas Otto]

Hi,

  cp writes to the file and !!overwrite!! everythin at the beginning
  including bootsector, logs, ....

 just more information:

basic step:
 1. /dev/hdb7 was 40G with 20G data and 1.5G overwritten at the beginning
 2. dd_rescue cp the device into the file
 3. I splitt the 40G file into 100M pieces
 4. do strings at the pieces to extract all strings
 5. start to search 'grep' for the data (ascii source code) I was missing
 6. 2 day ago I've done a backup with a tar file
 7. found tar file (was broken) but I was able to extract the ascii data
    ==>> !!! never use gzip Archive !!! <<== if someting get very very wrong
   you can always recover ascii data even if near everything was broken
  => well done :-)
 
advanced step:
1. build superblock on dev/hdb7
2. build transaction log on dev/hdb7
3. fsck.resierfs --rebuild-tree seems to work
4. after mounting dev/hdb7 the fs was empty  :-(
5. but lost+found was filled :-)
    -> got 1 important archive back :-)))
6. but something I dont like ...
   20G data, 1.5G overwritten at the beginning but got only 8.7G back in 
   lost+found. the 8.7G was mainly a couple of big archive files.
  together 122 files from ~10.000 files

=> question to the reiserfs guys 

   Why was the recover rate so bad?


mfg

  aotto

--rebuild-tree

[Cami]

Hi All,

Last night i done monthly maintence on all of my
mailhosts and after doing a reiserfsck, it looks
like i'll have to rebuild the tree on one of my
mail clusters (the other 8 clusters were fine)..

[mailhost01][/root]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/emcpowera1       152G   35G  117G  23% /var/spool/virtual

Can anyone tell me roughly how dangerous this is
and roughly how long something like this will take?
The filesystem stores all the users mailboxes in
maildir format so there are millions of files..

Any tips/comments would be appreciated..

Regards,
Cami

Re: --rebuild-tree

[Vladimir V. Saveliev]

Hello

Cami wrote:
> Hi All,
> 
> Last night i done monthly maintence on all of my
> mailhosts and after doing a reiserfsck, it looks
> like i'll have to rebuild the tree on one of my
> mail clusters (the other 8 clusters were fine)..
> 
> [mailhost01][/root]# df -h
> Filesystem            Size  Used Avail Use% Mounted on
> /dev/emcpowera1       152G   35G  117G  23% /var/spool/virtual
> 
> Can anyone tell me roughly how dangerous this is

it is not dangerous. Just, please, make sure you have recent reiserfsck.

> and roughly how long something like this will take?

hard to say. It depends on hardware. Given that 35 gb is not too much 
reiserfsck --rebuild-tree should not take too much. 2 hours? Vitaly may 
want to correct me, though

> The filesystem stores all the users mailboxes in
> maildir format so there are millions of files..
> 
> Any tips/comments would be appreciated..
> 

PS: please do not forget that backuping is important when dealing with 
user mailboxes even if you are running super reliable hardward and 
bugless software.

> Regards,
> Cami
> 
> 
> 

Re: --rebuild-tree

[Cami]

Hi Vladimir

>> Can anyone tell me roughly how dangerous this is
> 
> it is not dangerous. Just, please, make sure you have recent reiserfsck.

Yea.. I updated to the latest version last night..

>> and roughly how long something like this will take?
> 
> hard to say. It depends on hardware. Given that 35 gb is not too much 

Its a big ass Dell storage device (CX600) with fibre
drives so its quite a monster / quite fast..

> reiserfsck --rebuild-tree should not take too much. 2 hours? Vitaly may 
> want to correct me, though

mm.. thats not too bad at all..

>> The filesystem stores all the users mailboxes in
>> maildir format so there are millions of files..
>>
>> Any tips/comments would be appreciated..
> 
> PS: please do not forget that backuping is important when dealing with 
> user mailboxes even if you are running super reliable hardward and 
> bugless software.

Busy making a snapshot of the filesystem now..

Thanks!
Cami

Re: --rebuild-tree

[Vitaly Fertman]

On Tuesday 06 July 2004 12:56, Vladimir V. Saveliev wrote:
> Hello
>
> Cami wrote:
> > Hi All,
> >
> > Last night i done monthly maintence on all of my
> > mailhosts and after doing a reiserfsck, it looks
> > like i'll have to rebuild the tree on one of my
> > mail clusters (the other 8 clusters were fine)..
> >
> > [mailhost01][/root]# df -h
> > Filesystem            Size  Used Avail Use% Mounted on
> > /dev/emcpowera1       152G   35G  117G  23% /var/spool/virtual
> >
> > Can anyone tell me roughly how dangerous this is
>
> it is not dangerous. Just, please, make sure you have recent reiserfsck.
>
> > and roughly how long something like this will take?
>
> hard to say. It depends on hardware. Given that 35 gb is not too much
> reiserfsck --rebuild-tree should not take too much. 2 hours? Vitaly may
> want to correct me, though

fscking 35G should take minimum 1h, usually up to 2h. However 
semantic pass depends on the amount of files a lot, and as mailboxes 
have many small files fsck may take several hours. 

> > The filesystem stores all the users mailboxes in
> > maildir format so there are millions of files..
> >
> > Any tips/comments would be appreciated..
>
> PS: please do not forget that backuping is important when dealing with
> user mailboxes even if you are running super reliable hardward and
> bugless software.
>
> > Regards,
> > Cami

-- 
Thanks,
Vitaly Fertman