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So What Exactly Is a Director?
Since the definitions I've found have been less than specific, I'm going to identify some of the characteristics I believe are important when you move from a garden variety Fibre Channel switch to a Fibre Channel director given the cost difference per port.
- Hot upgradeable firmware
- For the switch – This might require a switch reboot at some future date
- For the control module
- Hot changeable with no impact rezoning of the switch (note that this can be a RAID or HBA issue, as they must relogin to the switch)
- Dual everything
- Power supplies
- Control modules (hardware/software module that allows management and monitoring)
- Hot pluggable everything (the backplane should be the only exception)
- Power Supplies
- Control modules
- At least 64 ports and hopefully over 100 ports
- LAN FC to WAN IP blades
In addition, these director-class switches should be able to achieve the almost mythical 5 9s of uptime, or about 5 minutes of downtime per year, but this brings to mind a few questions:
- Does every vendor define the term director-class switch the same way?
- Do the definitions used by the majority of vendors use the same criteria defined above?
Both answers are no, and in thinking about the issues, an additional set of questions arises. What are the performance requirements for director-class switches, and are the requirements I defined for director-class switch necessary in all cases?