Re: Solutions for a parallel system

Late response... was just catching up on some oracle-l email...

On Wed, Mar 5, 2008 at 4:30 PM, Ram Raman <veeeraman_at_gmail.com> wrote:

> With dataguard, my understanding is that the standby will have to be on a
> server of the same OS level, patch level, disk layout, etc. We do not
> have such a scenario here.
>

That's incorrect. You can certainly have different hardware specs, OS levels, patch levels, disk layouts, etc. The requirements are: - Same Oracle build and same major release on all servers. (e.g. 10.1.0.x.xon SPARC, x86, x86-64, etc)
- Same OS (Solaris, AIX, Red Hat, etc).

http://download.oracle.com/docs/cd/B19306_01/server.102/b14239/standby.htm#i72053

> Also they want to be able to work from the parallel environment (they may
> be making changes on their own). This means dataguard will not work as the
> standby will have to be in managed recovery mode. Even if we put it in OPEN
> mode and work on it, there is going to be a huge backlog of logs to be
> applied later on. I would think that would cause a big delay in refreshing?
> I was checking the redo log generated in prod for the past month. The
> average per day seems to be 20GB and maximum of ~60GB/day and min of
> 5G/day. Not sure how long it would to take to apply 60GB.
>

That all depends on your hardware. But I'd bet that you could open your DB in read/write mode during working hours (like 7am to 7pm) and then reverse the changes (with flashback database) and apply 60G of redo in just a few hours max (if not much faster).

Caveat: be careful if this is also your disaster recovery solution. If you have slower hardware and it was a busy day -- and then there's a primary site failure at 5pm then it might take a few hours to get your standby database online as the primary.

> Also this kind of setup would require manual intervention from the
> DBA everyday to put in managed recovery mode, open etc.
>

It could be scripted if you were sure that you wanted to automate it.

All that said, I think the biggest factor in data guard is price. It'll cost you extra; just gotta decide if it's worth it. Just my take on it. :)

-Jeremy

-- 
Jeremy Schneider
Chicago, IL
http://www.ardentperf.com/category/technical

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