On Wed, Jun 28, 2006 at 10:20:11AM +0200, Nicolas Dorfsman wrote:
Graphs told me that my hosts don't send/receive more than ~110 Mbits/ s . This raise an alert on the backup server which is installed with a GigEth interface and need to eat many backups flow simulteanously. So, I'm checking other GigEth equipped host. I have some solaris hosts with GigEth. Graphs are inconsistent
between interfaces details and TCP/IP general graphs. Take a look :http://www.unikservice.com/frp/tcpip.png http://www.unikservice.com/frp/i1.png http://www.unikservice.com/frp/i2.png
So, I'm suspecting an issue with collect or graphs. Could somebody
tell me where I should start to debug ?
Let me explain where these data come from.
The first graph ("TCP/IP statistics") are fed by data from the "netstat -s" command. This is (from a Solaris host):
TCP tcpRtoAlgorithm = 4 tcpRtoMin = 400 <snip> tcpCurrEstab = 0 tcpOutSegs =51380214 tcpOutDataSegs =17936799 tcpOutDataBytes =4114388778 <more snip> tcpInSegs =59097243 tcpInAckSegs =19928198 tcpInAckBytes =4108598170 tcpInDupAck =9794396 tcpInAckUnsent = 0 tcpInInorderSegs =34384580 tcpInInorderBytes =1273412387 tcpInUnorderSegs =970394 tcpInUnorderBytes =694993056 tcpInDupSegs = 70767 tcpInDupBytes =20764736
Hobbit tracks the "tcpOutDataBytes" and "tcpInInorderBytes" for the first graph. These are fed into an RRD file which computes the difference between two measurements, and from that it computes an average number of bytes sent over a 5 minute period. For the graph, this is then multiplied by 8 to go from bytes/second to bits/second.
What this means is that Hobbit does not count UDP traffic or other non-TCP traffic in this graph. If you have lots of streaming data which typically uses UDP, this can be a significant amount of data.
Also, it doesn't count out-of-order packets (retransmits, duplicate packets - see your OS documentation to learn exactly what goes into the "tcpInUnorderBytes" counter).
The second graph is fed by data from the Solaris' "kstat" utility, or AIX's "netstat -v" output. As far I understand, this counts raw Ethernet packet bytes - i.e. all protocols. They are fed into RRD files just like the TCP statistics.
So - most likely the difference is in what protocols are counted for each of the graphs.
Regards, Henrik