Re: DG for nologging

From: Stefan Knecht <>
Date: Wed, 7 Mar 2018 17:18:49 +0700
Message-ID: <>

On Wed, Mar 7, 2018 at 5:10 PM, Upendra nerilla <> wrote:

> A small detour on the SAN replication..
> I'm trying to understand the advantages and disadvantages of SAN
> replication over Data guard..
> I felt Data guard is very specific (to the DB replication task), it can
> validate the recoverability of the database continuously. SAN replication on
> the other hand, is useful in replicating complex application configuration
> to the DR site.. Also with SAN replication, we loose the ability to go
> point-in-time in the DR site (if the need arises?).

That's correct - you can't do point-in-time recovery.

> Also if multiple databases are being replicated with the same SAN
> replication group, we are unable to recover each of the database to its own
> point-in-time..

No, that's not correct. You'd set up your replication by LUN - not by server. This means individual file systems or ASM disks / disk groups. That gives you the ability to treat databases individually.

There are many more aspects to it. One thing that you certainly can't ignore as well is the Oracle licensing. If you have a "cold standby" and it's not running permanently, depending on your agreement with Oracle, you may not need to license it. A Data Guard standby runs permanently and must be fully licensed.

Of course, you also don't have any additional niceties such as the option of doing a reporting standby with Active Data Guard.

I have seen it used in environments where the archivelog volume exceeded what they could reasonably backup and replicate across the network (remember that in many environments the SAN infrastructure is separate from the regular network).

Received on Wed Mar 07 2018 - 11:18:49 CET

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