SmartTier matches data storage with data usage requirements. After data matching, the data can then be relocated based upon data usage and other requirements determined by the storage or database administrator (DBA).
As more and more data is retained over a period of time, eventually, some of that data is needed less frequently. The data that is needed less frequently still requires a large amount of disk space. SmartTier enables the database administrator to manage data so that less frequently used data can be moved to slower, less expensive disks. This also permits the frequently accessed data to be stored on faster disks for quicker retrieval.
Tiered storage is the assignment of different types of data to different storage types to improve performance and reduce costs. With SmartTier, storage classes are used to designate which disks make up a particular tier. There are two common ways of defining storage classes:
Performance, or storage, cost class: The most-used class consists of fast, expensive disks. When data is no longer needed on a regular basis, the data can be moved to a different class that is made up of slower, less expensive disks.
Resilience class: Each class consists of non-mirrored volumes, mirrored volumes, and n-way mirrored volumes.
For example, a database is usually made up of data, an index, and logs. The data could be set up with a three-way mirror because data is critical. The index could be set up with a two-way mirror because the index is important, but can be recreated. The redo and archive logs are not required on a daily basis but are vital to database recovery and should also be mirrored.
SmartTier is a VxFS feature that enables you to allocate file storage space from different storage tiers according to rules you create. SmartTier provides a more flexible alternative compared to current approaches for tiered storage. Static storage tiering involves a manual one- time assignment of application files to a storage class, which is inflexible over a long term. Hierarchical Storage Management solutions typically require files to be migrated back into a file system name space before an application access request can be fulfilled, leading to latency and run-time overhead. In contrast, SmartTier allows organizations to:
Optimize storage assets by dynamically moving a file to its optimal storage tier as the value of the file changes over time
Automate the movement of data between storage tiers without changing the way users or applications access the files
Migrate data automatically based on policies set up by administrators, eliminating operational requirements for tiered storage and downtime commonly associated with data movement
SmartTier policies control initial file location and the circumstances under which existing files are relocated. These policies cause the files to which they apply to be created and extended on specific subsets of a file systems's volume set, known as placement classes. The files are relocated to volumes in other placement classes when they meet specified naming, timing, access rate, and storage capacity-related conditions.
In addition to preset policies, you can manually move files to faster or slower storage with SmartTier, when necessary. You can also run reports that list active policies, display file activity, display volume usage, or show file statistics.
SmartTier leverages two key technologies included with Storage Foundation: support for multi-volume file systems and automatic policy-based placement of files within the storage managed by a file system. A multi-volume file system occupies two or more virtual storage volumes and thereby enables a single file system to span across multiple, possibly heterogeneous, physical storage devices. For example the first volume could reside on EMC Symmetrix DMX spindles, and the second volume could reside on EMC CLARiiON spindles. By presenting a single name space, multi-volumes are transparent to users and applications. This multi-volume file system remains aware of each volume's identity, making it possible to control the locations at which individual files are stored. When combined with the automatic policy-based placement of files, the multi-volume file system provides an ideal storage tiering facility, which moves data automatically without any downtime requirements for applications and users alike.
In a database environment, the access age rule can be applied to some files. However, some data files, for instance are updated every time they are accessed and hence access age rules cannot be used. SmartTier provides mechanisms to relocate portions of files as well as entire files to a secondary tier.
To use SmartTier, your storage must be managed using the following features: