From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yury Umanets Subject: Re: "Unformat" a ReiserFS partition : a testimony :-) Date: Tue, 25 Mar 2003 12:29:28 +0300 Message-ID: <3E802178.7010802@namesys.com> References: <3E7F5E33.4020709@info.ucl.ac.be> <3E7F9FD1.7060801@namesys.com> <3E7FA75F.3000808@mb.tu-ilmenau.de> <3E7FB063.2010205@namesys.com> <3E7FB90E.7010408@mb.tu-ilmenau.de> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: list-help: list-unsubscribe: list-post: Errors-To: flx@namesys.com In-Reply-To: <3E7FB90E.7010408@mb.tu-ilmenau.de> List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Manuel Krause Cc: reiserfs-list Manuel Krause wrote: > On 03/25/2003 02:26 AM, Yury Umanets wrote: > >> Manuel Krause wrote: >> >>> On 03/25/2003 01:16 AM, Yury Umanets wrote: >>> >>>> Nicolas Vanderavero wrote: >>> > [...] > >>>> >>>>> 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? >> >> >> I'm sure that usual mount+umount cannot do bad things like this. But >> why did you ask me about that? I mean that Nicolas has explicitly >> formatted > > > No, sorry, for bothering again with my unclear questions. > > I meant mounts happening just after a mkreiserfs run in failure and > wanted to make sure for myself that they don't destroy more. > (Rest of the story: Acoustically a mount after mkreiserfs does MORE on > disk than a mount of a previously mounted fs. So I just only thought of > a first mount changing Nicholas' circumstances before successful > recovery.) Probably you mean journal replaying in new filesystem on mount? If so, then it is not big deal, due to journal is created empty. > > >> his partition by means of using mkreiserfs. And I know that >> mkreiserfs creates new super block at 16 block and also leaf for root >> node, first bitmap and journal. >> >> As old bitmap is corrupted, --rebuild-tree -S will be apparently needed. > > [...] > >> So the plan is the following: >> >> (1) Backup your data. >> (2) Rebuild super block if it had some special like relocated journal. >> (3) Rebuild tree with partition scanning --rebuild-tree -S. >> >> This should reanimate your old partition but expect, that you will >> found some of your data in the /lost+found directory. > > [...] > > Thank you, You are wellcome. > > > Manuel > > > -- Yury Umanets