Content Services uses the BLOB architecture but also makes use of an extension of the principle: the use of the BFILE data type. The data is stored in operating system files external to the database. As far as programmers are concerned, a BFILE column is just another column, but the database administrator and the system administrator know that they are actually independent files stored in the database server’s file system.This gives the administrator the freedom to store the BFILE data on any devices, even within tape libraries or on optical devices that would normally be unusable for an Oracle database.
Use of BFILEs gives you the ability to migrate a large part of the data stored within Content Services to comparatively low-cost and high-volume devices. A multi-terabyte Content Services datastore might be uneconomical to maintain on high-speed disks, but if the actual data (not the indexing information) could be migrated to tape, it becomes feasible. Clearly, a sophisticated tape management system is necessary.
For example, the ADSM (Adstar Distributed Storage Manager) tape library software from IBM can migrate files to tape if they have not been accessed for a certain period of time, while leaving them visible in the file system’s directory; they are transferred back from tape to disk on demand.
No comments:
Post a Comment