Re: Dataguard / Archive Logs

  • From: David Sharples <davidsharples@xxxxxxxxx>
  • To: Carel-Jan Engel <cjpengel.dbalert@xxxxxxxxx>
  • Date: Wed, 1 Jun 2005 20:16:17 +0100

wow, you should write a book on this stuff :-)

the san would be synchronous writes.

So If i can try to put it simply - it would work that way, but
dataguards on the face of it seems the better, cheaper solution ?

On 6/1/05, Carel-Jan Engel <cjpengel.dbalert@xxxxxxxxx> wrote:
> David,
> Is the SAN replicating synchronously or asynchronously?
> Data Guard needs less bandwidth than storage based replication. Most of t=
> times SAN's are configured to replicate asynchrously. Just think of the
> amount of data that needs to be sent over when storage is replicated: Red=
> writes (all members), archive copies (maybe also redundant?), the writes =
> data files, and the updates of the controlfile. Mind that storage based
> replication is often disk block based, or even disktrack-based! You can
> imagine what amount of data needs to go through the pipe for that. Compar=
> that with just sending the redo entries with Data Guard. The standby site
> will take care of applying them, writing to data files and performing the
> archive job locally.=20

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