Centera represents the fixed-content storage platforms from EMC Corporation; disk-based storage appliances and software for the storage and retrieval of content such that it cannot be altered. The Governance and Compliance Plus editions of Centera (more below), provide hardened compliance features; specifically, the ability to force documents to be retained for specified periods without allowing for premature, audited deletions.

Centera is designed around the concept of Content Addressed Storage (CAS), which, in a nutshell, stores the actual data as an object and returns to the application a unique, "Content Address," that is itself derived from the actual content to be stored. In this way, if the content should be retrieved, altered, and then replaced in the archive, Centera will automatically generate a new address for the content and store it separately; leaving the originally stored content intact and unchanged. In addition to storing the actual data, Centera also extracts--and separately stores--metadata about the stored data (including the Content Address itself and the defined retention period for the content) in a representation called a Content Descriptor File, or CDF. An address is then generated for the stored CDF, and it is this address that is returned to the requesting application. That application can then retrieve the content by presenting the Content Address to the Centera platform, without requiring specific file names or URLs (the actual physical storage location of the data is transparent to the client application). Mirror copies are stored both of the original content and the CDF.

Access to Centera from applications is facilitated via the Centera API, which provides basic interface functions including Store, Retrieve, Exists, Delete, and Query. An SDK allows for the interfacing of applications via either these high-level functions, or lower level functions allowing for interactions at the pool, clip, or tag level. The Centera API can be accessed from multiple platforms, including Windows (NT/2000/2003 Server/XP Pro), Solaris, Linux, AIX, and more.

The Centera platform itself is a RAIN (Redundant Array of Independent Nodes), which is deployed in 6-foot, 19-inch cabinets. Capacity is typically added in 4-node increments (nodes are either access or storage nodes); with each cabinet capable of providing from 8 to 96 TB of raw capacity. A smaller hardware infrastructure is rack mountable and targeted primarily to mid-sized enterprise deployments; with usable capacities ranging from 3.5 to 5.5 TB, depending on node type disk size.

Centera platforms are offered in 3 primary configurations: The rack-mountable Centera for Midsize Enterprises, with features as above; the Compliance Edition Plus, which adds automated compliance features including enforced retention periods, retention "classes" (where retention periods for a document can be specified with references, instead of discreet retention periods), and DoD compatible document electronic shredding; and the Governance Edition, which includes the capabilities of the Compliance Edition Plus as well as remote management, audited deletions (where a record can be prematurely deleted provided a strictly defined auditing path is followed), and a Sysop controllable default retention period (in the Compliance Edition Plus, the default retention period is infinity).

Additional retention-based features available in the Compliance Plus and Governance Editions only are Event-Based Retention (EBR), which allow for the setting of an undetermined retention period on a document when it is initially written, with a specific retention period then assigned when a defined event occurs; and Litigation Hold capabilities, which allow for the override of retention should specific records be required to be retained beyond their original retention periods.

Companion products to the Centera storage arrays include:

- Centera Backup and Recovery Module, facilitating backup of Centera storage to tape via EMC NetWorker, Symantec NetBackup, and IBM Tivoli Storage Manager (TSM)

- Centera Mainframe HSM Migrator, which enables Centera systems to plug into IBM's DFSMShsm (Data Facility Storage Management Subsystem)

- Centera Seek/Centera Chargeback Reporter, which provide indexing and searching capabilities for a Centera archive as well as the ability to assign and manage customized categories of archived data

- Centera Universal Access, a soft appliance (can be installed on a separate, external server or directly on a Centera node) that facilitates access to Centera content via CIFS, NFS, FTP, or HTTP

New to the Centera product line is a updated version of the core operating system, CentraStar. According to EMC, the new version doubles the number of objects that can be stored on a single disk drive, to 25 million objects per 500 or 750 GB drive. Other new features include the ability to separately manage the products' application, management, and replication traffic; and logging and auditing enhancements. The new OS is available to existing systems running CentraStar 2.4 or later under software maintenance contracts as a free upgrade.

Centera is available now. Visit the EMC Corporation Web site for further information.