On Wed, Aug 26, 2009 at 6:23 AM, Mikael Abrahamsson <[email protected]>wrote:
> On Wed, 26 Aug 2009, Ash Net wrote: > > The reason for performance degradation solely seems to be latency related >> since there's tons of b/w available in the lab setup and over 10G lanphy >> paths. Do people still deploy QOS for better traffic management on the >> lanphy interfaces even with no saturation?. >> > > All the protocols you mentioned are "query/response" ones and thus they > take a big hit when latency is introduced. > > I know several companies who nowadays has a wan simulation device between > the clients and servers in their dev labs, just so that the developers will > develop applications that actually work in real life, not just in the 1/10 > ms latency of the dev environment. Imagine the difference in a latency > environment between doing a single nested SQL query, as opposed to doing 1 > returning a list, and then doing one query per list entry. In a 1/10ms > environment the difference might not be noticeable, but in a 100ms > environment it most certainly will. > > At several ms network latency you're effectively dealing with harddrive > latencies as opposed to almost memory latencies, and thus techniques that > work akin to NCQ or alike needs to be employed. Failure to do so will create > performance problems in real life. > > Serious feelings of deja-vu. We lived through a similar scenario over the last few months. GigE "WAN" (really a MAN) with 3-5ms latency. Had to install some WAN accelerators, 'cos they promise to fix everything. WAN Accelerators don't work in this scenario for the reason Mikael mentions (the IO subsystem of a WAN accelerator is in the 2-3ms range.) Only real answer is to get application developers to code for the Internet at large, rather than for <1ms LAN. Of course our devs don't even like their dev servers being 3-5ms away... Tim:> _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
