If you mean "why change from Alpha to Coppermine", then the answer is that CuMine is a faster CPU than Alpha, increasing the overall throughput of the filer.
If you "why add a second CPU to the motherboard", then the answer is that if NTAP is re-engineering the ONTAP OS to take advantage of a multiprocessor architecture, the the second CPU will increase the throughput of the filer.
I suspect that NTAP has plans for a multiprocessor architecture. There are several approaches to this, and I do not know which they are taking:
1) True co-equal multiprocessing where the processors share the work on an equal basis, parsed by the OS.
2) Slave/master multiprocessing, where one processor is the master, and, in conjunction with the OS, parses work to the second CPU.
3) Specialized multiprocessing where each processor is responsible for a specific set of tasks. For example, the second processor may be a dedicated I/O processor, responsible for controlling the I/O subsystem and all aspects of moving data from main memory to the I/O bus and vice versa.
4) "On board clustering" (my term) where each of the two processors have their own RAM and perhaps a NUMA connection between them working almost identically to the current two-filer clustered fail-over configuration. This would be akin to the old Tandem computer architecture, which is where NUMA got its start. This approach by NTAP would probably require less re-engineering of the OS and offer a level of failsafe redundancy and reduced cluster failover configuration cost.
I don't know what approach NTAP is taking. |
