> > So, if the OS can mirror corruption, why wouldn't Oracle mirror it
> > too? I have SEEN BOTH (how about you?) the OS AND Oracle mirror
> > "software" corruption.
>
> Because with OS mirroring, you have LGWR only writing once, and then that
> being copied by the OS to the mirror. One write. One stuff up. One
> corruption. Mirrored. With multiplexing, LGWR writes twice (or three times,
> if you do 3-way multiplexing). With two (or more) writes, it is highly
> unlikely that LGWR would introduce the same corruption at the same point in
> the redo stream. Therefore, multiplexing protects you against software
> corruption.
An interesting problem here. Suppose LGWR introduced some corruption into
one of the group members (actually it will likely be OS, not LGWR because
the latter writes the same information, but it does not matter). The redo log
member
is archived by the ARCH. What is really to stop it from taking the faulty one?
Received on Wed Dec 25 2002 - 03:01:40 CST
