first block in ext3 filesystem

[Yang Chengwei]

On Mon, Aug 06, 2012 at 11:19:57AM -0700, Manish Katiyar wrote:
> 
> On Mon, Aug 6, 2012 at 11:04 AM, Prashant Shah <pshah.mumbai at gmail.com> wrote:
> 
>     Hi,
> 
>     I came across this
> 
>     $sudo dumpe2fs /dev/sda1
> 
>     4KB Block Size
>     Group 0: (Blocks 0-32767)
>       Primary superblock at 0, Group descriptors at 1-1
> 
>     1KB Block Size
>     Group 0: (Blocks 1-8192)
>       Primary superblock at 1, Group descriptors at 2-2
> 
>     Why does first block start from 0 in the 4KB block size partition and
>     1 in 1KB block size partition ?
> 
> 
> Let's say superblock is always written at a fixed offset of 1024 (they have to
As Shah said, the superblock is always written at a offset 1024. When
the block size is 4096, offset 1024 is in the first block (block 0),
while the block size is 1024, offset 1024 is in the second block (block
1).

Since group descriptor locates after superblock, so Group 0 starts from
1 when the block size is 1024 byte.

Please correct me if I'm wrong.

--
Thanks,
Chengwei

> because e2fsck has to find it) in the filesystem. What would be the block
> numbers with block sizes 1k and 4k ?
> 
>  
> 
> 
>     Regards.
> 
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> 
> 
> --
> Thanks -
> Manish
> 

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