Today’s storage technology encompasses all sorts of storage media. These could include WORM systems, tape library systems and virtual tape library systems. Over the past few years, NAS and SAN systems have provided excellent reliability. What is the difference between the two?
• NAS (Network Attached Storage) units are self-contained units that have their own operating system, file system, and manage their attached hard drives. These units come in all sorts of different sizes to fit most needs and operate as file servers.
• SAN (Storage Area Network) units can be massive cabinets – some with 240 hard drives in them! These large 50+ Terabyte storage systems are doing more than just powering up hundreds of drives. These systems are incredibly powerful data warehouses that have versatile software utilities behind them to manage multiple arrays, various storage architecture configurations, and provide constant system monitoring.
For some time, large-scale storage has been out reach of the small business. Serial ATA (SATA) hard disk drive-based SAN systems are becoming a cost-effective way of providing large amounts of storage space. These array units are also becoming main stream for virtual tape backup systems – literally RAID arrays that are presented as tape machines; thereby removing the tape media element completely.
Other storage technologies such as iSCSI, DAS (Direct Attached Storage), Near-Line Storage (data that is attached to removable media), and CAS (Content Attached Storage) are all methods for providing data availability. Storage architects know that just having a ‘backup’ is not enough. In today’s high information environments, a normal nightly incremental or weekly full backup is obsolete in hours or even minutes after creation. In large data warehouse environments, backing up data that constantly changes is not even an option. The only method for those massive systems is to have storage system mirrors – literally identical servers with the exact same storage space.
How does one decide which system is best? Careful analysis of the operation environment is required. Most would say that having no failures at all is the best environment – that is true for users and administrators alike! The harsh truth is that data disasters happen every day despite the implementation of risk mitigation policies and plans.