In the real world, memory shortfalls are much more devastating than having a CPU bottleneck. Two primary indicators of a RAM shortage are the scan rate and swap device activity. Here are some useful commands for monitoring both types of activity:
I am working on a new Splunk deployment at work, and as part of that project, I have to build a centralized syslog server. The server will collect logs from all of our systems and a forwarder will pass them along to Splunk to be indexed. That alone would be easy enough, but I think that logs are too important to leave to just one syslog server. Sending copies of the log data to two destinations may allow you to sustain outages in half of the log infrastructure while still getting up-to-the-minute logs in Splunk.
The first line of
vmstat represents a summary of information since boot time. To obtain useful real-time statistics, run
vmstat with a time step (eg
The word "
sar" is used to refer to two related items:
This facility stores a great deal of performance data about a system. This information is invaluable when attempting to identify the source of a performance problem.
One thing that's been clear since the launch of Oracle's new Sun SPARC T5 and M5 systems: it got IBM's attention. Judging from their response, they seem to be... I'm going to go with concerned.
nfsstat can be used to examine NFS performance.
In Unix, every object is either a file or a process. With the /proc virtual file system, even processes may be treated like files.
netstat provides useful information regarding traffic flow.
netstat -i lists statistics for each interface,
netstat -s provides a full listing of several counters, and
netstat -rs provides routing table statistics.
netstat -an reports all open ports.