RE: DW setup

Its interesting to me what you guys are attempting -we're setting up a large DWH as well and use a similar technology "BC copy " to backup the dbs etc .

In the process you outlined - I do question the need for two copies of the DWH - a dbs for writing ETL's to and another for read-only .Why do that ? You cannot create the second copy till you finish the ETL's to the first instance anyway & the structures on both instances are exactly identical .

When the ETL's loading the first instance are complete ,use checkpoint to backup the dbs and turn the instance into your day time read only instance.

Thanks,
Vikas kawatra
Aera Energy LLC
(661) 665-5819

Email: vkawatra_at_aeraenergy.com

"Either Lead ,follow or get out of the way"                                                    

-----Original Message-----
[mailto:becker.bill_at_marshfieldclinic.org] Sent: Monday, October 14, 2002 10:49 AM
To: Multiple recipients of list ORACLE-L

Hello,

BACKGROUND:
We've been planning a 300GB datawarehouse architecture for Oracle 9.2 on Solaris, and have proposed the following: 1) 2 separate instances of Oracle 9.2,

• Instance A will be the staging instance, all ETL processing will take place here
• Instance B will be the query instance, all reporting activity will take place here 2) Once data has been transformed, copy the tablespace metadata from Instance A to Instance B using transportable tablespaces feature 3) The physical datafiles will be fast-copied from Instance A to Instance B using a vendor feature called Checkpoints (not Oracle's definition of checkpoints).

Point 3 needs further explanation: both of these instances will be connected to Network Attached Storage (NAS) from a vendor named Procom. They have a feature called Checkpoints, which quickly creates a read-only copy of a data volume
(I believe this is similar to network appliance's snapshot feature, and EMC also
has something like this, but the name escapes me). Checkpoints are very fast to create, and can result in a read-only copy of 200GB of data in 1 - 2 minutes. At present, we use them for backup purposes only, and they work well.

Instance A, the staging instance, will use the read-write Oracle datafiles located on the procom read-write volumes. Instance B, the query instance, will use datafiles located on a read-only procom volume, which also happens to be the checkpoint volume of the read-write volume used by Instance A. The checkpoint volume will be refreshed daily, from the staging volume, when the daily ETL stream has completed. The query instance datafiles will be dropped and re-created daily via the procom checkpoint, and the tablespace metadata will be plugged in using transportable tablespaces.

We have verified that Oracle works OK using plugged-in read only tablespaces located on a procom read-only checkpoint volume.

QUESTIONS:  (too much to hope for)
1) Is anyone else out there using this type of configuration with procom?

   If so, how well does this work? Any comments, problems?

 (more realistic)
2) Is anyone else out there using a similar configuration with a comparable

   vendor feature like checkpoints? Any performance problems? Any comments, problems?

 (more desperate)
3) Is anyone running a large Oracle data warehouse using primarily read-only

   tablespaces? Any comments, problems? How do you refresh them?

 (last resort)
4) Does anyone care to comment on the above configuration? good idea...bad idea?

Thanks

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Author: Kawatra V (Vikas) at Aera
  INET: vkawatra_at_aeraenergy.com

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