Call for Consistency in
SAN Components"> First and foremost, before a SAN implementation can begin, many hours of research should be done ahead of time. By combing through a vendors Web site you can easily find out which operating systems are actively supported by that vendor and you can also learn which products are certified to work together. The primary benefit of open standards--as opposed to proprietary technologies--is that you dont have to sell your soul to one vendor to get a working implementation. While Fibre Channel is indeed an open standard, its openness can stand some improvement. Interoperability in the SAN space is much improved compared to the past, but it is still far from being something we would characterize as plug-and-play across multiple vendors. Fibre Channel vendors and users will have to endure some interoperability glitches as the technology improves and becomes more mainstream, very similar to the development of Ethernet several years ago.For this reason we recommend that once you start building your SAN, you should try as much as possible to standardize on specific components to simplify troubleshooting and minimize the likelihood of interoperability based failures. Given the current state of the market in the Host Bus Adapter (HBA) segment, we recommend that you choose a single HBA vendor and stick with it for the long haul. While it is possible to implement HBAs from several vendors together in a single SAN, from a management standpoint an extra vendor is an added headache, since you need to stay on top of the new firmware, drivers and management utilities that are constantly released by different vendors. It is also important to be consistent with your drivers and firmware for the HBAs. Occasionally weve seen communications errors occurring because of mismatched firmware and drivers within a SAN. For Fibre Channel switches, the recent E-port spec should allow you to uplink switches from different vendors to expand SANs. It should be noted, however, that the E-port spec is still not universally implemented by all of the switch vendors. We highly encourage you to check the switch vendors site for interoperability information before making any purchasing decisions. Like HBAs, we recommend that you stick with one brand of switch, since most of the switch vendors (Vixel and Qlogic in particular) make excellent management tools which allow IT managers to manage all of the switches in their SAN from a single point (provided they all come from that vendor). Storage Arrays and tape libraries are the only components that are OK to mix and match a bit to take advantage of pricing wars between vendors. JBODs (Just a Bunch Of Disk) units are popular in testing labs because of their low cost, but these units dont provide redundancy unless you run software RAID from your server operating system. RAID vendors like Hitachi Data Systems, which last year entered a partnership with Sun Microsystems, makes excellent high end systems while smaller vendors like MTI Corp. offer some interesting low end to mid-range RAIDs.
The key word for every SAN implementation should be consistency. Unlike Ethernet and other networking technologies, you cannot expect to buy random SAN components and slap them together with everything working efficiently out of the box. It is extremely important to remember that a poorly configured SAN will do more than just abruptly stopping your applications, it could lead to massive data loss and corruption.