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On 04/04/2011 06:29 PM, Aaron van Meerten wrote: > Hi Adrian, Hi! > I was the one who was performing these speed tests, so let me give a > little bit of detail about them. > > We had 6 file, each of size 1GB. These files were placed one per > tray on each of 6 trays of 15 2-TB disks in RAID-6. The data server > in question has 24GB of RAM, and a 10Gb ethernet link. > > The test was performed from 100 worker nodes, which all attempted to > read all six files in parallel. > > As a note, it's unlikely that this was bottlenecked or affected by > the RAID cards because it's pretty clear that all 6 files would > easily fit in the kernel page cache. So this is mostly a test of > page-cache->xrootd->NIC throughput rather than RAID throughput. > > I hope to do some more comprehensive testing which will include the > RAID controller in the mix, but the interesting result here is simply > that the softirqd symptom that Charles mentions was in fact our > bottleneck, and when that was removed we were able to move our data > at line speed. Thanks for info! Great work :) now i have some start idea to toy with :) Adrian