DW 2.0 Workshop - Bill Inmon - Archival Sector

7/28/2019 DW 2.0 Workshop - Bill Inmon - Archival Sector

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a presentationby W H Inmon

ALTERNATE STORAGE

Copyright Inmon Consulting Services, 2008C


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data warehouses grow large rapidly



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data warehouses age over time



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Actively used data

Dormant data

Performance is greatly hurt by keepinga lot of data on disk storage that is dormant



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an arterywithcholesterol

Lots of

cholesterolNot muchcholesterol

lots ofdormant data



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Lots ofdormant data

Not muchdormant data Removing dormant data

from the data warehouseis the single most importantthing the designer can doto improve performance



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It is much less expensiveto place data on different

forms of storage



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High performancedisk storage

Near line storage

Archival storage

There are three storage media that

data can be sent to



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Data that has a very highProbability of access

Data that has a lowprobability of access

Data that needs to be keptregardless of probability of access



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Can be accessed in online time

Can be accessed in near online time

Cannot be accessed in online time



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Near line storage can be tightly coupledor loosely coupled with disk storage

Looselycoupled Tightly

coupled



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When the near line storageenvironment and the diskstorage environment arenot tightly coupled, they mustbe queried separately

of course the result sets can be mergedindependently if desired

query query

resultset

resultset



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When the disk storage and the near line environmentare not tightly coupled, the data base design can be

independent and the data can be managed separately



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query

When the disk storage environment and thenear line storage environment are tightly

coupled, a single query can access both setsof data without knowing where the data is



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When the disk storage and the near line storageenvironments are managed in a tightly coupled manner,

the data base design must be identical and the units ofstorage must be managed together



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Archival storageis always looselycoupled with otherstorage media



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archival assumptions over time

- data will degrade

- metadata not stored directly with data will be lostor otherwise corrupted

- related data (key/foreign key) will be lostand or corrupted



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copy over

occasionally it is a good practice to copy overarchived data to ensure the longevity andintegrity of the data



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sparemachine

while archival data is sitting

around waiting to be used,create passive indexes inanticipation of future needs



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cross media

storage manager

data can flow from the archival environmentto the disk environment if needed



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Archival and near line data canalso flow into the data mining/

exploration warehouseenvironment as well



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Granularity of data -

In both the near line and the archival environment, dataNeeds to be kept at the granular level. It is optional and

Sometimes useful to keep the data at the summary level.



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operating system/

dbms

Near line storage needs to be

kept current/compatible with theoperating system/dbms

Archival data usually is not current with theoperating system/dbms



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One of the most important uses

of archival and near line datais that of passive security

In passive security we look atthe records of events todetermine what the extent ofthe damage is or how tofind out next time how toprevent a disaster



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processor

Dont just let archival data sit there and wait for activity.take an idle processor and constantly build indexeswaiting for future unknown needs.

Then when it comes time for using the archival

environment it will be fast and easy to access

Building passive indexesin the archival environment


Documents

DW 2.0 Workshop - Bill Inmon - Archival Sector