SSD's are not about bandwidth, they're about latency. With a raid array of cheapo disks we can also get 3GB/s bandwidth, more than most 2 socket nodes effectively can handle.
Only theoretically a higher bandwidth will be possible (benchmarks huh). However getting 20 bytes from a SSD is in the few dozens of microseconds, versus several milliseconds for the cheapskate disks. That factor of 50-100 difference roughly in latency difference is the reason SSD's exist. Any bandwidth test of a SSD is total nonsense. On Feb 9, 2013, at 10:32 PM, Bill Broadley wrote: > On 02/09/2013 01:22 PM, Vincent Diepeveen wrote: >> SATA is very bad protocol for SSD's. >> >> SSD's allows perfectly parallel stores and writes, SATA doesn't. >> So SATA really limits the SSD's true performance. > > SSDs and controllers often support NCQ which allows multiple > outstanding > requests. Not sure if that fits the definition of "perfectly > parallel", > but it does allow for outstanding requests to be answered in the order > of the devices choosing. > > In fact the higher IOP rates would be impossible without it. Note how > the latency for a single IOP is much higher than peak 1 second / (peak > IOPs). > > > _______________________________________________ > Beowulf mailing list, Beowulf@beowulf.org sponsored by Penguin > Computing > To change your subscription (digest mode or unsubscribe) visit > http://www.beowulf.org/mailman/listinfo/beowulf _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org sponsored by Penguin Computing To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
