File System : Block Groups

[Valdis.Kletnieks at vt.edu]

On Sat, 25 May 2013 23:56:50 +0530, Dibyayan Chakraborty said:

> The main purpose is to replicate the super_block and other important
> information so that it can be recovered in case of data corruption. Other
> purpose is to enable efficient storage in order to minimize defragmentation
> and head seek time.
>
> My questions are :
>
> Are there any other purpose of this ?

What, that isn't reason enough? ;)

> How it is possible to detect that there is some corruption in the main
> super_block information ? Is some kind of check sum is used ? What is the
> standard way of doing it ?

In fs/ext4/super.c, see the various ext4_superblock_csum-* functions
and their callers, around line 115 to 160 or so. Figuring out what other
filesystems do is left as an exercise for the reader. ;)
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