RAID 1 or Hammer

[Gergo Szakal]

"nntp.dragonflybsd.org" <mneumann at ntecs.de> wrote in message 
496b8121$0$881$415eb37d at crater_reader.dragonflybsd.org">news:496b8121$0$881$415eb37d at crater_reader.dragonflybsd.org...
Hi,

I'm curious if RAID 1 (mirroring) really helps to protect data loss. Of 
course if a whole disk "dies", RAID 1 has the advantage that
I have an identical copy. But what happens if only a sector of one disk
contains bad data. How can the RAID controller decide which is the
correct sector? Or would the disk detect such a case and return an error?

IMHO RAID provides redundancy and higher data availability while HAMMER 
mirroring
provides data safety by by backups. Having a non-0 RAID array is not equal 
to data
safety IMHO. Only backups can provide that.

Just my very own 0.02 though.