RE: Some Dataguard is good, lots more must be better?(specifically, when do most actual failovers really occur?)
- From: "Laimutis Nedzinskas" <Laimutis.Nedzinskas@xxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 21 Sep 2006 08:46:46 -0000
No, I do not confuse. I just was not 100% sure if Oracle can do it
because I've never tested it myself.
The point is I've never used this option is that together with Data
Protection one wants High Availability which means that time lag is
contradicting this requirement. In numbers if 15 minutes downtime is
allowed then recovery must be 15 minutes. I am not sure how to calculate
maximum lag allowed as it depends on machine speed and redo size and
probably redo contents.
Brgds,
Laimis N
________________________________
From: Carel-Jan Engel [mailto:cjpengel.dbalert@xxxxxxxxx]
Sent: 20. september 2006 21:27
To: Laimutis Nedzinskas
Subject: RE: Some Dataguard is good, lots more must be
better?(specifically, when do most actual failovers really occur?)
On Wed, 2006-09-20 at 17:07 +0000, Laimutis Nedzinskas wrote:
Now regarding DG with time lag. Well, it is not a good option
for
maximum data protection(as Oracle defines it.) At least I do not
know
how to protect redo logs in this mode. Which means that for
maximum data
protection you have to have a standby database which is in
complete
sync, i.e. running in maximum protection mode(at least most of
the
time.) BUT I am not sure if file system snapshot technique can
achieve
this either.
Laimutis,
Maybe the delay concept confuses you a little. Maximum protection and
Delay actually go together very well.!
Maximum protecion gurantees that redo is written at the standby at the
time the commit finishes.
Delay allows you to wait a certain amount of time to apply the redo.
So, all redo IS protected in maximum protection mode, even if a delay is
configured. The standby can be in read only mode and still protect your
data.
Best regards,
Carel-Jan Engel
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Other related posts:
- » RE: Some Dataguard is good, lots more must be better?(specifically, when do most actual failovers really occur?)
- » RE: Some Dataguard is good, lots more must be better?(specifically, when do most actual failovers really occur?)
- » RE: Some Dataguard is good, lots more must be better?(specifically, when do most actual failovers really occur?)
- » RE: Some Dataguard is good, lots more must be better?(specifically, when do most actual failovers really occur?)
- » Re: Some Dataguard is good, lots more must be better?(specifically, when do most actual failovers really occur?)
