Help! Why does my connection to my linux box slow to a crawl?
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Help! Why does my connection to my linux box slow to a crawl?
Hi,
I have a linux server that has seemingly random network slow downs. This server is mainly my dvr. I'm starting to think it's a hardware problem, but that's just a gut feeling. I don't really know how to determine if it isn't.
Slow summary:
SSH, HTTP, VNC incoming traffic are all affected
Outgoing traffic seems ok. I haven't tested this as much.
Looks like you have a gigabit nic but the switch is only 100Mb, there are no errors though so it doesn't look like a physical network problem. Try running sar to collect some stats... ?
My Mandriva distro doesn't have sar. Is there another utility I can use? Does plugging a gigabit card into a 100mb router typically cause this type of behavior?
A gigabit card should autonegotiate its speed with the router when the computer or router is first turned on. To answer your question no there should be no problem with mixing a gigabit NIC with a 100 mb router.
In addition to using sar, which will show the usage of system resources over time, I would run Wireshark during the times that the computer is responding slowly. You can look for problems such as duplicate packets and out of order packets. These kinds of things would indicate a hardware problem. You can also look for other problems using Wireshark such as lots of SYN packets or lots of RST packets. These would indicate a configuration problem with the network clients or other problems coming from the client computer trying to interact with the server.
Last edited by stress_junkie; 05-03-2011 at 07:19 AM.
I installed sysstat and have it set to collect. In my original post, I forget to mention that I ran wireshark during one of the slowdowns and didn't record much, if any, activity. I saved the output file from before and will look at it again after I become more familiar with the utility. Hopefully, I'll have something to report in a few days to a week.
Well, it's been a few weeks and the problem still exists. I captured a sar -A during one of the outages. Should I post the whole output? It's large.
Symptoms now include dropping entirely off the network from both directions. (No route to host) . When I disconnect the cable and reconnect it, it works again for a short time.
I just noticed this in the log after I unplugged and replugged the cable in:
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