RE: Oracle Data Guard

Hi Kitty,

Never heard of that, but I'm interested in your experiences, and the architecture of iReflect. The only advantage of Data Guard I can tell you is that it comes for free with your Oracle licences.....

Regards, Carel-Jan

• There will allways be another 10 last bugs --

At 12:14 9-12-03 -0800, you wrote:
>Hi All,
>
>I am working on a similar project here. I am wondering if anyone in the
>list ever compared Oracle Data Guard with iReflect from Data Mirror.
>Please share your experience with us.
>
>Thanks,
>Kitty
>
>
>
>
>-----Original Message-----
>Sent: Monday, December 08, 2003 6:54 PM
>To: Multiple recipients of list ORACLE-L
>
>
>
>
>Hi Carel,
>
>What if 50% of tables doesn't have Primary/Unique
>keys, how it is going be with LSB then? Can you please
>explain more.
>
>with thanks,
>Vi
>
>
>--- Carel-Jan Engel <cjpengel.dbalert_at_xs4all.nl>
>wrote: > Comments inline
> >
> > At 14:54 8-12-03 -0800, you wrote:
> > >Hi Carel,
> > >
> > >That is good help, can you please send me the pdf
> > that
> > > you implemented there then.
> >
> > Was on its way already
> >
> >
> > > Tell me one thing I agree that we some
> > >times
> > >(rather most of the time ) generate less redo so
> > we
> > >should be smooth. Can you tell me is there any
> > >releation between LSB and Primary keys, I read
> > like
> > >LCR(logical Change Request) is based on Primary
> > keys
> > >as It does not depends on Transaction at that time.
> >
> > Because LSB 'reverse engineers' SQL from the redolog
> > info, it needs to get
> > hold of the right rows. The rows get
> > inserted/updated/deleted, and _a_
> > unique identification, not being the rowid, is
> > required. So, every row
> > needs to be uniquely identified.
> >
> >
> >
> > >Have you implemnented LSB successfully?
> >
> > Yes, using a PSB / LSB combination for standby and
> > reporting purposes
> > respectively.
> >
> >
> > >with many thanks,
> > >Vi.
> > >
> > > --- Carel-Jan Engel <cjpengel.dbalert_at_xs4all.nl>
> > >wrote: > Comments inline
> > > >
> > > > At 13:34 8-12-03 -0800, you wrote:
> > > > >Hi Tanel,
> > > > >
> > > > >
> > > > >Much appreciated, The fact is I am interested
> > in
> > > > >Logical standby rather than physical.
> > > > >
> > > > > Our 30-50% of our Production data needs to
> > be
> > > > >replicated to another database and where they
> > will
> > > > >have their processing and batches.
> > > >
> > > > It all depends on the amount of redolog you
> > > > generate. When that's pretty
> > > > much, you waste some resources by transporting
> > > > online/archived redologs you
> > > > actually don't need.
> > > >
> > > >
> > > > > Now We didn't go to Snapshot because It is on
> > > > >multiple tables (where we didnot have PK's and
> > > > many
> > > > >tables) and due to performance issue I didn't
> > want
> > > > to
> > > > >use Snapshots (they did not want any tables to
> > be
> > > > >truncate before being loaded even via
> > snapshots).
> > > >
> > > > So, they don't like nologging operations like
> > > > truncate, not even on the
> > > > standby database?
> > > >
> > > >
> > > > > The best option I think is Logical Standby
> > > > Database.
> > > > >Or Can you please suggest me any other means.
> > > > >
> > > > > Replication should be quicker like
> > once
> > > > in
> > > > >every 20 minutes, Even Transportable tablespacs
> > > > does
> > > > >not work here since they need all tables to
> > 24*7.
> > > >
> > > > LSB might work, but do not consider the option
> > of
> > > > failing over to it. Be
> > > > aware that, altough in maximum protection mode
> > your
> > > > redolog arrives at the
> > > > SB system within the transaction, it doesn't get
> > > > applied there instantly.
> > > > SQL Application takes place _after_ the
> > log-switch
> > > > on the Primary. When you
> > > > take 10 minutes of redolog, and perform a
> > logswitch,
> > > > the SQL Apply process
> > > > might even take longer than 10 minutes to
> > complete
> > > > processing of the
> > > > redologfile. There is a risk that not every
> > > > transaction arrives within 20
> > > > minutes at the LSB. So, your log-switching
> > frequency
> > > > and the amount of redo
> > > > you generate per unit of time both play a major
> > role
> > > > in the refresh rate of
> > > > the LSB.
> > > >
> > > > I'll send you the PDF of a DG Special I did in
> > Kista
> > > > a few months ago.
> > > >
> > > >
> > > > Regards, Carel-Jan
> > > >
> > > > -- There will allwasy be another 10 last bugs --
> > > >
> > > >
> > > > >Any suggestion would be more helpful.
> > > > >
> > > > >with thanks,
> > > > >Vi.
> > > > >
> > > > >
> > > > >
> > > > >--- Tanel Poder <tanel.poder.003_at_mail.ee>
> > wrote: >
> > > > >
> > > > >Hi All,
> > > > > > >
> > > > > > > can any one let me know kindly the
> > following
> > > > info.
> > > > > > >
> > > > > > > 1) Has any one used the Oracle 9i Data
> > Guard?
> > > > > >
> > > > > > Yes, physical standby and successfully.
> > > > > >
> > > > > > > 2) If yes then, is there any performance
> > > > impact
> > > > > > on
> > > > > > > Target/Source server database.
> > > > > >
> > > > > > Your database has to be in archivelog mode,
> > but
> > > > when
> > > > > > you are thinking such
> > > > > > solutions as DG, then you probably are
> > already
> > > > > > running archivelog anyway.
> > > > > >
> > > > > > If you run in maximum protection or maximum
> > > > > > availability, yes there is. The
> > > > > > impact depends mainly on network connection
> > > > between
> > > > > > primary and standby(s)
> > > > > > and the speed of redolog disks. You could
> > tune
> > > > these
> > > > > > by using faster
> > > > > > network, enabling jumbo frames and SDU size
> > if
> > > > using
> > > > > > Gbit ethernet, also
> > > > > > setting lgwr and log apply processes
> > priority
> > > > higher
> > > > > > than others.
> > > > > >
> > > > > > > 3) any drawbacks using Data Guard.
> > > > > >
> > > > > > You should set your database or critical
> > > > tablespaces
> > > > > > to force logging mode
> > > > > > in order to transfer all changes to standby
> > in
> > > > > > physical standby. That means,
> > > > > > performance improvements which take
> > advantage of
> > > > > > nologging operations (such
> > > > > > insert append nologging etc), will not run
> > that
> > > > fast
> > > > > > anymore.
> > > > > > In logical standby, I think there's no such
> > > > > > requirement, but I don't
> >
>=== message truncated ===
>
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Author: Carel-Jan Engel
  INET: cjpengel.dbalert_at_xs4all.nl

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