Scalability and Manageability

A very important characteristic of a VLDB is its large size. Storage scalability and management is an important factor in a VLDB environment. The large size introduces the following challenges:

  • Simple statistics suggest that storage components are more likely to fail because VLDBs use more components.

  • A small relative growth in a VLDB may amount to a significant absolute growth, resulting in possibly many devices to be added.

  • Despite its size, performance and (often) availability requirements are not different from smaller systems.

The storage configuration you choose should be able to handle these challenges. Regardless of whether storage is added or removed, deliberately or accidentally, your system should remain in an optimal state from a performance and high availability perspective.

This section contains the following topics:

Stripe and Mirror Everything (SAME)

The stripe and mirror everything (SAME) methodology has been recommended by Oracle for many years and is a means to optimize high availability, performance, and manageability. To simplify the configuration further, a fixed stripe size of 1 MB is recommended in the SAME methodology as a good starting point for both OLTP and data warehouse systems. Oracle ASM implements the SAME methodology and adds automation on top of it.

SAME and Manageability

To achieve maximum performance, the SAME methodology proposes to stripe across as many physical devices as possible. This can be achieved without Oracle ASM, but if the storage configuration changes, for example, by adding or removing devices, then the layout of the database files on the devices should change. Oracle ASM performs this task automatically in the background. In most non-Oracle ASM environments, re-striping is a major task that often involves manual intervention.

In an ILM environment, you apply the SAME methodology to every storage pool.