sda2 is corrupted

[Reindl Harald]

Am 06.07.2012 18:28, schrieb Jim:
> On 07/06/2012 12:11 PM, Jim wrote:
>> On 07/06/2012 12:02 PM, Michael Schwendt wrote:
>>> On Fri, 06 Jul 2012 11:22:55 -0400, Jim wrote:
>>>
>>>>>> /dev/sdb1 is now a blockwise copy of /dev/sda2
>>>>> On 05.07.2012, Jim wrote:
>>>>>
>>>>>> There are some important data files I must save off of sda2
>>>>> Before you start any rescueing, take a full snapshot of the partition,
>>>>> e.g. "dd if=/dev/sda2 of=/dev/on_an_external_disk"
>>>>>
>>>>>
>>>>>
>>>> that is exactly what I did but nothing shows up on /dev/sdb1 external
>>>> drive after dd has completed .
>>> That makes no sense. If /dev/sdb1 points at a corrupted filesystem,
>>> above "dd" command will copy the same corrupted filesystem to /dev/sda2.
>>> That's expected and okay, if you only want to keep that one read-only as
>>> a backup of the originally corrupted filesystem. Then you can play with
>>> rescueing sdb1 - but be careful and remember that sda2 is supposed to be
>>> your backup of a corrupted filesystem. Don't mess with that one.
>>>
>>> Better would have been to copy sdb1 to an image file instead of another
>>> partition device.
>>>
>> sda2 is the corrupted file system.
>> I'm trying to send a img of the sda2 to backup hard drive sdb1 .
>> I' running into a read-only filisystem on sda3 , but :
>>
>> # mount | grep sda3
>>
>> /dev/sda3 on / type ext4 (rw,relatime,seclabel,data=ordered)
>>
>> it say it is rw but when i run the dd command i get a read-only filesystem.
> 
> mount | grep sdb1
> /dev/sdb1 on /media/backup type ext4 (ro,relatime,seclabel,errors=continue,data=ordered)
> 
> 
> now I find out that sdb1 ,external/USB hard drive is read-only, what command would I use to make it a read-write
> partition.

boag this is the result of "I run  dd if=/dev/sda2 of=/dev/sdb1  to copy, supposely
a 26gb image to sdb1 but i do not see a image on  sdb1"

as i said in my first reply today

>> no, just stupid because you do not read manuals nor know anything about
>> basic-commands and that is why you destroyed /dev/sdb1 if there were
>> data by overwrite the whole partition

so you have to create a NEW fileystem on /dev/sdb1
you have overwritten it with the source-partition of you dd-command

also you did not realize why we are suggested to use dd or ddrescue
before any other attempt - because you get a BLOCKWISE image of the whole
partitionor even disk which can be backuped mutilple times to test restore
strategies

but if you are start using dd the wrong way you are pretty soon at the end
try to undersatnd what commands are supposed to do and read their manpages
CAREFULLY before use them, use google to learn about them and AFTER that
think if you are really sure to be the right person for data-restore
on a damaged disk

BUT even if you are coming to the conslusion you are the wrong one
the FIRST step to make CAREFUL a dd-image of a appearently dying
FS/disk is the right way becasue if the disk is dead whoever can continue
try to restore data from this image



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