how to boot or access problem file system

[PJ]

Roland Smith wrote:
> On Thu, Jul 30, 2009 at 01:40:58PM -0400, PJ wrote:
>   
>> What can be done to access a file system that seems to have the boot
>> sector screwed up?
>>     
>
> Do you mean the filesystem's superblock? Or the slice table (partitions
> in PC parlance) or the freebsd partitions (disk labels)? Because the
> boot sector is not part of any filesystem. 
>
> The best way to try repairs is to make a complete copy of the partition
> with dd(1), and experiment on the copy. That way you cannot further screw
> up the original!
>
> To check a UFS filesystem, use fsck_ffs(8). First, try if the preen
> option '-p' is sufficient to fix the filesystem. If the superblock is
> corrupt, try using the -b option to specify an alternate superblock. See
> the manual page.
>
>   
>> The /usr files should be ok but how to access?
>>     
>
> Use fsck_ffs to try and repair the filesystem.
>   
how can I use it if I can't boot or access the file system?
>> I get errors that the file system is full and I have no idea of how to
>> deal with the boot up - the help message is no help!
>> Boot says it cannot find a kernel... surely there must be some kind of
>> recovery process even if nothing has been backed up. Surely FreeBSD must
>> be have something that functions like certain software does on MS ?
>>     
>
> Maybe the sleuth kit (sysutils/sleuthkit) can help you recover files. 
>   
How would that be? I can't access the disk or the file system and I
can't boot....
>   
>> I don't have a problem with irrecoverable files, I would just finally
>> understand how things work and what can be done on FBSD.
>>     
>
> Make regular backups. Especially before big upgrades.
>   
Maybe the real problem is that the manual is too screwed up (why are
there so many problems being brought up on the mailing lists? we can't
all be that stupid.)
> Roland
>   


-- 
Hervé Kempf: "Pour sauver la planète, sortez du capitalisme."
-------------------------------------------------------------
Phil Jourdan --- pj at ptahhotep.com
   http://www.ptahhotep.com
   http://www.chiccantine.com/andypantry.php