On Thu, 20 Dec 2007, Gregory Stark wrote:
Surely such machines have kickass memory backplanes too though? How could it ever be reasonable to have an i/o controller with more bandwidth than your memory?
Dann had the right general numbers here--max of 6.4GB/s between processors and you might coax an aggregate of double that out of the DDR RAM with 2 4-way interleaved banks of memory. Let's call it 12GB/s theoretical max. If the theoretical max of the disks is 2GB/s, that's only a 6:1 headroom, and with a decent cache rate it's not outrageous to imagine you could bottleneck on memory with some things before you run out of disk throughput.
Right now I think a lot of the disk bottlenecks are seek-limited more than anything, but SSD will knock that one out for apps that are more about throughput than maximum storage. I could already switch to SDD usefully today for some of what I do that's in that category, it's just a bit too expensive to do yet; soon, though.
Just trying to usefully estimate where the edge of that back of the envelope should go to.
-- * Greg Smith [EMAIL PROTECTED] http://www.gregsmith.com Baltimore, MD ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
