The concept of Information Lifecycle
Management has been around for many decades. In a
nutshell, ILM is the intelligent archiving of historical
Oracle data on cheaper tertiary media, like inexpensive
disks, optimal jukeboxes and magnetic tape.
ILM - It's all about the cost of storage
In a perfect world, with negligible-cost
fast storage, ILM would be unnecessary because offloading
and storing historical data would not be driven by
economics. However, even though disk and SSD is now
cheaper than ever before, archiving historical data remains
problematic, especially within the realm of Oracle auditing
for regulatory compliance.
Government regulations such as SOX, GLB
and HIPAA require auditing of updates (DML) and disclosure
(SQL selects). According to the law, organizations
must provide complete audit trails for all DDL (i.e., schema
changes), DML (e.g., updates, insert, deletes), and select
confidential patient information.
Time-Series Audit Chart
As highly active data ages out and
becomes low-activity, ILM allows the DBA to easily move it
away from the high-cost storage onto cheaper media.
The basic idea of ILM is to develop a
hierarchy of storage based on storage cost and data
activity. This being, ILM:
Leaves highly active current data on
high-speed solid-state disk (e.g. SSD which can be 300x
faster than platter disks)
Archives low-activity historical data
to cheaper platter disk and tertiary media (tape)
Oracle introduced an ILM assistant in
Oracle 9i, an Apex (HTML-DB) application, to offload and
archive large volumes of historical database information.
Oracle notes that as long as Oracle Application Express is
used in Databases 9i and up, Apex is useful because it:
Manages ILM environments via a GUI
Defines lifecycle definitions
Manages security and compliance
Advises when data needs to be moved,
The Oracle 11g ILM Assistant
In Oracle 11g, ILM has been enhanced to
incorporate Oracle partitioning to allow easy data movement
at the partition level. This includes the all-important
exchange partition syntax. As highly-active data ages out
and becomes low-activity, ILM allows the DBA to easily move
it away from high-cost storage onto cheaper media.
Oracle says that the basic ILM steps include:
Defining the data classes
Creating storage tiers for the data
Creating data access and migration
Defining and enforcing compliance
To allow for easy data movement within
ILM, Oracle leverages their Automatic Storage Management
(ASM) and partitioning features. These features are
offered within an 11g ILM assistant, a GUI designed to
remove the tedium from managing many layers of storage.
Oracle 11g introduces these new additions within ILM:
Oracle advanced data compression for tables, LOBs and
"Interval", "Ref" and "virtual column" partitioning
11g partitioning methods (list-list, list-range, list-hash
In summary, ILM is more of a collection
and integration of existing tools, such as ASM and
partitioning, than a separate product. Furthermore,
the Apex front-end ILM assistant provides an easy interface
to the management of multi-tiered data.