Snmp on Evan Hoffman

Using rrdtool to generate server load & bandwidth graphs

Fri, 17 Feb 2012 15:32:25 +0000

I’ve been using MRTG and routers2.cgi for years to graph the various aspects of a server that warrant monitoring. I’ve long known that they used something called rrdtool to do… well, something, but never had a need or desire to figure out exactly what that was.

But, having just moved my site to a new server, I was curious how the server would handle the load. Rather than setting up some behemoth like Nagios or Zabbix, which are full monitoring/alerting suites, I just wanted graphing. As I said, in the past I’ve used MRTG or routers2.cgi for this but both of them were overkill for me in this case. Since both of them used rrdtool, I figured that was a good place to look.

TP-Link TL-WR841ND v7 802.11n router, wireless dies after a few days

Wed, 16 Mar 2011 00:46:57 +0000

I mentioned in a previous post that I got the TP-Link TL-WR841ND 802.11n wifi router and it solved the speed problems I was noticing with wifi connections since going from FiOS to Cablevision. This seems to be the case still, however I’ve now had another problem with the TP router. Basically, wireless becomes unusable and the web UI becomes inaccessible. The SSID still shows up but I can’t get an IP address. When accessing it from the wired LAN via a browser, the connection times out - apparently whatever’s going on inside the router is also crashing its internal webserver.

Using Zabbix for SNMP monitoring disk usage percent for Windows hosts

Fri, 05 Nov 2010 09:44:22 +0000

A few years ago we moved from Nagios to Zabbix for our server monitoring needs. I wasn’t a big fan of Nagios, finding it a pain to manage with its myriad configuration files. It’s probably gotten better since I last toyed with it but since we moved to Zabbix I haven’t had much reason to look at Nagios again.

I also try to use SNMP monitoring for everything. SNMP is widely supported - all sorts of hardware has SNMP support, and with the net-snmp package you can pretty easily create your own SNMP-monitorable stuff on Linux. Since almost all of our stuff runs on Linux this has worked out pretty well, but our Exchange server is probably going to be running on Windows for the foreseeable future. Windows has SNMP support, it’s just not on by default. However, even when it’s enabled it doesn’t have the simple “dskPercent” monitoring I’ve come to know and love with net-snmp on Linux, which simply tells you how full a given disk is as a percent. This makes it easy to set alerts when a disk reaches 80% full.