Why is there a dm-raid array in MBL?

WD Legacy Products My Book Live
1 
root@mybooklive's password: 
Linux MyBookLive 2.6.32.11-svn70860 #1 Thu May 17 13:32:51 PDT 2012 ppc
READY!

MyBookLive:~# cat /proc/mdstat 
Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4] 
md0 : active raid1 sda2[1] sda1[0]
1999808 blocks [2/2] [UU]

unused devices: <none>

Anybody knows why there is a raid array in my single drive  MBL?

How does this setup help to avoid data loss?

2

That’s the system RAID.   It’s made of two different partitions.   If one partition becomes corrupt, the RAID can still function and potentially correct the issue.

3

it’s still a little strange to me … you agree that both array members are mounted all the time? So if there was a potential data corruption, it’s most likely to corrupt both partitions in the same way, agreed? I’d perfectly understand a backup partition, that is kept unmounted, so in any case of corruption it would not affect that backup.

4

Haidube wrote:

 So if there was a potential data corruption, it’s most likely to corrupt both partitions in the same way, agreed?

it’d be nearly impossible for both partitions to be corrupted.  That’s the whole point of RAID to begin with.

And don’t EVER confuse RAID with a “backup.”   They are NOT the same thing.  ;)

What if the drive developed a bad sector, preventing a READ?  … and what if that bad sector was in the kernel?  Since only the kernel has the capabilities of changing boot loaders, how would it boot?   From where would it get its instructions to drop the “bad” partition and retry with the “good” partition?