This may seem overly obvious, but have you simply run a netstat while the slowdown occurs to see what the box(es) are doing at that point in time? Alex On 2011-03-28, at 6:32 PM, mcclnx mcc wrote: > I don't think it is cable problem. The reason are: > > 1. it happen every 3 to 4 weeks once. > > 2. problem last 4 to 5 hours then back to normal. > > 3. not one server has this problem, several servers on that rack all have problem at same time. > > > > --- 11/3/28 (一)，Peter Larsen <plarsen at famlarsen.homelinux.com> 寫道： > >> 寄件者: Peter Larsen <plarsen at famlarsen.homelinux.com> >> 主旨: Re: [CentOS] centos server network speed check??? >> 收件者: centos at centos.org >> 日期: 2011年3月28日,一,下午5:41 >> On Tue, 2011-03-29 at 05:13 +0800, >> mcclnx mcc wrote: >>> we have several servers on same rack and servers are >> all inside firewall. Centos version from 4.X to >> 5.X. sometime the connection are very slow (compare to >> servers on other racks also inside firewall). >>> >>> we discuss with network engineer he ask us use "ping" >> and traceroute" to check. Both tools response time are >> good but if we connect through application like Web browser, >> database, or DELL OPMN tool. The response time is very >> very slow. >>> >>> This situation normally last 4 to 5 hours then it back >> to normal. Does there has way to check "real" network >> response time so we can show to network engineer. >> Otherwise they always say "no problem". >> >> miitool and ethtool >> >> Check that you're running at the right speed; sometimes bad >> cables will >> make the negotiation go bad. Sometimes you just connect to >> the wrong >> switch port. You may also note if the switch has hard-set >> values about >> the negotiation such as duplex settings. Make sure they >> match on both >> ends. You should be full duplex unless there's a very very >> good network >> reason not to. >> >> Lastly, check ifconfig output. Make sure there's no errors >> reported. If >> you have a high error count, it's a good bet the cable is >> bad or the >> sync settings are wrong. >> >> -- >> Best Regards >> Peter Larsen >> >> Wise words of the day: >> Showing up is 80% of life. >> -- Woody Allen >> >> -----內含下列夾帶檔案----- >> >> _______________________________________________ >> CentOS mailing list >> CentOS at centos.org >> http://lists.centos.org/mailman/listinfo/centos >> > > > > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centos