On Jan 12, 2009, at 9:13 PM, Gergo Szakal wrote:
"nntp.dragonflybsd.org" <[email protected]> wrote in message news:496b8121$0$881$415eb...@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?
When the controller will try to perform an I/O operation it will fail
on the faulty disk (the disk with the bad sector). As a result the
controller will be able to decide which is the correct sector.
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.
