On Sat, Nov 12, 2011 at 05:02:50PM +0800, Liu Yuan wrote: > I can not give a simple answer yet before I finish it. For your > description about large data size, I have no doubt that it will benefit > rotational disk utilizing the underlying extent-like feature and > neutralize the seek overhead, but how about network performance for big > data transfer? It seems to me that we trade off the fragmentation > against wasteful bandwidth. A single 128MB object will fill the 1000Mb > nic to the full, so parallel data transfer seems very restricted. Being > that said, though I don't have much thought on this issue and my > networking knowledge is not qualified to make the pertinent remark. We don't nessecarily have to transfer all 128MB in a single I/O, just make sure we allocate large sequential areas. Many I/Os will be smaller anyway, so it won't matter, but at least we have a way to fill the disk queue with I/Os that avoid seeking if we want to (for large, streaming I/O). |