Re[4]: 2 Node RAC Standby -- A mix of Managed Recovery and Read only?
- From: Kamus <kamusis@xxxxxxxxx>
- To: Carel-Jan Engel <cjpengel.dbalert@xxxxxxxxx>
- Date: Fri, 07 Jan 2005 20:22:39 +0800
the extra downtime is not the only risk.
Image that if ur standby site has a disk failure (one archived log file
is damaged), but at office time, u even don't try to recover these
archivedlog, so u can't get any information from standby's alertlog said
something is going wrong. then later at afternoon, you get a primary
site failure ...
On Thu, 06 Jan 2005 20:20:40 +0100
Carel-Jan Engel <cjpengel.dbalert@xxxxxxxxx> wrote:
> A read-only standby can continue receiving redo. So, the only risk is
> extra downtime, because there is more redo to apply when the primary
> fails whilst the standby is in R/O mode. Your description is a perfect
> way of eating the cake and have it: run reports on the standby during
> office hours, of course with data actualized up till the morning, and
> let the standby apply the receive logs during the night. There is always
> a standby, the recovery time of it may vary.
>
> I didn't know of the 'mixed standby setup' you mentioned. Thank you for
> bringing this up. Another challenge on my todo list for future tests.
>
> Best regards,
>
> Carel-Jan Engel
>
> ===
> If you think education is expensive, try ignorance. (Derek Bok)
> ===
>
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>
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>
> On Thu, 2005-01-06 at 18:46, Steven Patenaude wrote:
>
> > On Thu, 06 Jan 2005 20:02:17 +0800, Kamus <kamusis@xxxxxxxxx> wrote:
> > > Sorry, I don't think so.
> > > First, the storage is cheaper and cheaper this days, buy onemore cheap
> > > dell-emc Storage System maybe enough.
> > > Second, by setting up 2 independent standby databases we could get a
> > > much more flexible anti-disaster environment. such as 1 be a physical
> > > and the other be a logical, or 1 be a instant apply and the other be a
> > > delayed apply, etc...
> >
> > While _we_ know the one true way, management often doesn't agree that
> > disk hardware, maintenance costs, datacenter floor space, etc. is
> > cheap (or cheap enough).
> >
> > I don't remember (and need to get on with my day job), does a standby
> > database continue to catch the redo stream (but not apply it) while it
> > is in readonly mode? If so, you could alternate the standby between
> > readonly and "catch up" modes as needed.
> >
> > > Though oracle said standby database support RAC, at least so far I won't
> > > use this function.
> >
> > Obviously the standby can be configured for RAC but I agree about only
> > having one instance up. The documentation says you can have one
> > instance catch the redo stream and another apply it. Has anyone tried
> > this? It seems to me this would be added complexity (and chances for
> > problems) with very minimal performance gains.
> >
> > Steven
> > --
> > //www.freelists.org/webpage/oracle-l
>
>
--
Kamus <kamusis@xxxxxxxxx>
éäå1Gçéçïæèçæåää:-)
A Oracle8i & 9i Certified DBA from China
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