RE: Cascading Physical Standbys?
Date: Tue, 18 Nov 2014 20:36:00 +0200
Message-ID: <CAKb+SBU9kKpP5rJX_5ZOLd6Vq4gfcfzgJ_m-yKM6NfWSvtEN1Q_at_mail.gmail.com>
Check all farsync feature of 12c
On 18 Nov 2014 20:18, "Mark W. Farnham" <mwf_at_rsiz.com> wrote:
> This could be useful, for example, if standby #1 is local campus active
> dataguard (or cloned) on a separate machine with a second network so the
> work of forwarding the archived redologs is up to the (possibly remote)
> standby machine for all of storage, network consumption, and cpu cycles.
>
>
>
> That could give you near real time currency locally and consume less
> production cpu and network bandwidth on the machine(s) hosting the primary.
>
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> I’d say different things can go wrong rather than more things that can
> break.
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>
> I have never measured the cpu and network cost of multiple arch_dest
> definitions, and of course that would vary according to both your exact
> load and your exact hardware. Whether or not license cost is an issue will
> vary by topology and contract, but often it is not cost effective to burn
> fully licensed cpu when other cpus could be doing the work, and especially
> if the extra network bandwidth consumed burns production cpu cycles due to
> spin waits.
>
>
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> Without a detailed knowledge of service level requirement for the primary,
> reporting for the first standby, and recoverability overall it is
> impossible to know whether this topology would be good for a given customer.
>
>
>
> It sounds as if your data center has many customers. Whether internal or
> external, there is a non-zero value to having everyone do things the same
> way. Of course that is subject to still meeting service level requirements,
> off-loaded reporting requirements, and recoverability requirements.
>
>
>
> Good luck!
>
>
>
> mwf
>
>
>
> *From:* oracle-l-bounce_at_freelists.org [mailto:
> oracle-l-bounce_at_freelists.org] *On Behalf Of *Dba DBA
> *Sent:* Tuesday, November 18, 2014 11:42 AM
> *To:* ORACLE-L
> *Subject:* Cascading Physical Standbys?
>
>
>
> I am not sure what the official term is. Its when you have
>
>
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> Primary -> Standby -> Standby
>
> DB Version 11g and up.
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> I work in a large data center. I was talking to another DBA and one of her
> customers is doing this. I asked her why we would do this intead of just
> using 'multiple arch_dest' locations then write the archive logs to separe
> LUNs that under the surface map to separate RAID Groups. Little more work
> up front for storage, but when its done its done.
>
>
>
> I see a cascading DB as more stuff that can break. The rationale I got is
> that
>
>
>
> Standby #1 is for report and that Standby #2 is for DR. However, if
> standby #2 is not current, then standby #3 is current.
>
>
>
> Anyone ever set this up before? I am just looking for rationals for doing
> this. I am likely missing something.
>
-- http://www.freelists.org/webpage/oracle-lReceived on Tue Nov 18 2014 - 19:36:00 CET