[EMAIL PROTECTED] (Doug Miller) wrote on 03/24/2004 11:45:32 AM:
> With the MC Service guard they can TOC a system (Transfer of control) at
a
> drop of a hat and be back up and running on the 2nd machine very
> quickly. The 2nd machine grabs the ip address of the primary and people
> just have to log in again and pick back up where they were.
I agree with Doug - this can be a very slick implementation if done
correctly. I've worked with RFS installations on HP-UX with
MC/ServiceGuard, and on AIX with HACMP. The clustering software nicely
handles the fail-over, with the assumption that UniData is running with RFS
to handle the cleanup. However, it's critical to ensure that UniData is
set up correctly in the shared environment. There are components that need
to be available on the shared disk, and other components that need to be
unique to each system. If all of the pieces aren't in the right places,
the TOC could result in a failure when starting UniData, or an invalid RFS
recovery. Tread softly and test thoroughly when implementing this sort of
solution. Also make sure the clustered environment is set up by somebody
that understands it inside and out. This can be very complex to implement.
Back to the original question, there's no fundamental problem with running
RFS over a SAN. If at all humanly possible, you'll want to isolate the
before-image, after-image, file-level, and archive logs from the database
files. This is important for performance, since you don't want heads and
controllers busy updating the database and log files at the same time.
Also, if there is an unrecoverable media failure (not too likely these
days, but it does happen!), you don't want it to take out the database
files the archive logs at the same time. Otherwise you'll have to resort
to your backups with no way to recover to the point of the failure.
Tim Snyder
IBM Data Management Solutions
Consulting I/T Specialist , U2 Professional Services
[EMAIL PROTECTED]
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