Re: Help required on Data Guard

From: Mark Bole <makbo_at_pacbell.net>
Date: Tue, 30 Nov 2004 01:37:22 GMT
Message-ID: <m9Qqd.51738$QJ3.18946@newssvr21.news.prodigy.com>

Howard J. Rogers wrote:

> Joel Garry wrote:
> [snip]
>

>>
>> RAC is, as you say, for a single database.  Data Guard uses log files
>> to replicate the transactions to another database.

>
>
> Minor quibble: it actually uses processes, either LGWR or ARCn, to
> trasport redo. No files actually get shipped between machines, as such.
>
> HJR
When quibbling, are you talking about RAC or Data Guard?

More specifically, in the case of Data Guard, are you saying that no matter how far beind, the primary database, once it notices it can talk to the standby again after an interruption, actually re-reads the previously locally archived redo logs, and then sends the data, as re-read, to the standby via log transport, where the redo log file is then re-instantiated on the fly?

Hmm, I'd never thought of that. But of course, that *would* be much more portable across OS platforms. I did notice that the timestamps of 'catch up' log files were contemporaneous with the catch-up, but I thought that was just a sloppy way of copying files (for example, not using the equivalent of "-p" = preserve option).

-Mark Bole Received on Mon Nov 29 2004 - 19:37:22 CST