The most decentralized model uses storage directly attached to individual servers (DAS). The decentralized model is probably the most common for branch offices since it is the simplest and cheapest to implement and puts the fewest demands on support personnel. It is also the hardest to manage, the most inefficient in using available storage space and requires provisions for backup, such as backup over the LAN. VARs and systems integrators need to take into account when setting up remote office, branch office (ROBO) storage.
A centralized model with the storage at the local site, such as a SAN, offers high scalability and faster data access while still giving good manageability. However, it is often the most expensive of the approaches because of the need to establish a separate, fairly sophisticated storage facility in the branch office. It can also pose support problems because of a lack of technically knowledgeable personnel on site. Often, companies choose this model when the branch office is likely to expand significantly in the near future.
The hybrid model is in some ways the most difficult to design because, to get the maximum benefit, it needs to be carefully matched to the present and future needs of the local office. For example, in a hybrid storage architecture, deciding what kinds of data will be kept locally and what will be kept centrally is very important. Properly done, the hybrid model provides a good mix of scalability, data access and ease of support.
One complicating factor in designing storage for a branch model is the potential support cost of getting it wrong. By their nature, branch offices don't have the kind of resources for troubleshooting and support that a data center does, which means additional support, especially on-site support, can be disproportionately expensive.
This article orginally appeared on SearchWinComputing.com.
Rick Cook has been writing about mass storage since the days when the term meant an 80 K floppy disk. The computers he learned on used ferrite cores and magnetic drums. For the last 20 years he has been a freelance writer specializing in storage and other computer issues.
This was first published in April 2007