The Evolving Device Connections

Along with network connections, SAN connectivity options continue to evolve , encompassing more storage devices. In fact, integrating FC communications with the myriad tape solutions available has been underway for some time. Further enhancements to tape media will likely come in the form of optical and solid state disks, as well as advanced forms of caching mechanisms.

Integrating Tape Solutions

Tape media is currently integrated using an external bridge/router solution (see Chapter 14). Bridge/router connections are increasingly integrating solutions whereby FC connectivity is built into the tape controller devices, allowing for a cleaner installation, not to mention a closer integration into the controller mechanism that takes advantage of individual tape manufacturer's differentiators and functions. This level of integration comes closer to allowing tape to function more efficiently by talking directly to the switch port. Developing tape media is an ongoing effort of the FC standards groups.

Tape media remains a particularly sensitive area within data centers, given the large investments that must be made in these realms. The capability to change and start additional library areas that support additional media is no small undertaking. One of the largest bottlenecks in support processing within data centers is backup, which gets performed on a daily, weekly, and monthly basis. This takes up an inordinate amount of time compared to the production processing that takes place in direct support of the company's business. (Additional details on backup/recovery processes are covered in Chapter 22.) Integrating tape library functions into the SAN is a significant task. Even though it may seem trivial at the beginning, the importance of the complete analysis of this integration greatly impacts the backup cycle-both positively and negatively.

The positive aspect is enhanced performance when moving backups to FC speeds. Even though you're throttled by the limitations of the tape device, it remains significantly faster than a slower and copy-redundant direct-attached model that can quickly congest an IP-based network infrastructure. There is also the potential value that a 'server-less' backup scenario can be supported within your SAN configurations. Here, the elapsed time savings in running backup jobs can be as great as 50-75 percent, meaning that a typical backup cycle which runs seven hours would now take only three and a half. Because of this, significant overhead savings can be obtained over and above the amount of production processing time placed into the cycle.

The negative aspect is the increased cost to the facilities and recovery operations that result from integrated SAN tape configurations. The additional costs are needed to allocate tape drives for the FC SAN switch. More than likely, these will be dedicated given the non-sharing that FC SANs are currently encumbered with. In addition to this are the extra facilities necessary for extending the tape library functions-even though it may integrate into the current library system.

Another negative aspect is the consideration of the recovery operation that will ultimately have to take place. This requires the ability to locate proper backup tapes, log tapes, and control tapes. The tapes have to be dumped to the appropriate volume within the devices from the attached server, and then applied in the event of database recovery (which most may be). This isn't necessarily any different than normal recovery, other than that all of this has to be performed within the SAN environment, which, unless it's taken into consideration beforehand, can very quickly get out of hand.

Looking for an Optical Connection

Another popular media that will potentially integrate into the SAN is optical, or CD and DVD drives and libraries. Historically, these devices have seen limited usage as removable media libraries within enterprise network environments because of their performance as a write-once disposable media and physical read/write performance at the optical device level. Both of these conditions have improved to the degree that optical media and drives can be used for special applications of information distribution, reference, and, in some cases, effective backup media.

Optical devices can be integrated into a SAN using a bridge/router device to perform the same interconnection as Tape media. The use of SCSI optical drives with a SAN router can integrate the CD and DVD media sufficiently for production processing. The production of CD or DVD for distribution from digital sources, such as post processing of entertainment and educational packages, can benefit from the increased speed of SANs and allow it to process in a connection-oriented environment to facilitate the total bandwidth of the SAN.

Front-end processes of these applications, the preprocess production, where digital entertainment and educational products are edited and produced, have been an early adopter of SAN technology. This is largely due to bandwidth and storage capacities , as well as the ability to provide a Class 1 connection, which facilitates the streaming media production requirements for digital video files. These configurations can form either the production system for manipulating and creating digital video/audio effects, or the distribution system to move entertainment or educational files out to a network.

Actually, optical drives and autoloader packages have recently become available in NAS configurations. The NAS device is bundled with optical media drives and an autoloader system while maintaining the NAS file access front end and Plug and Play connection to an IP network. Given the future integration of NAS and SAN, the integration of NAS optical systems into SAN will become another alternative to SAN/ NAS integration and optical media usage with the SAN environment.