sar can be an incredibly helpful utility when examining system performance (especially after the fact), but if not used regularly it's easy to forget which flags to use
This short post details a number of useful arguments to pass
# Basic Output
sar
# CPU Usage per Core
sar -P ALL
# Memory Usage
sar -r
# Swap Usage
sar -S
# I/O
sar -b
# I/O by Block Device
sar -d -p
# Check Run Queue and Load Average
sar -q
# Network Stats
sar -n DEV
# Where DEV can be one of the following
#
# DEV – Displays network devices vital statistics for eth0, eth1, etc.,
# EDEV – Display network device failure statistics
# NFS – Displays NFS client activities
# NFSD – Displays NFS server activities
# SOCK – Displays sockets in use for IPv4
# IP – Displays IPv4 network traffic
# EIP – Displays IPv4 network errors
# ICMP – Displays ICMPv4 network traffic
# EICMP – Displays ICMPv4 network errors
# TCP – Displays TCPv4 network traffic
# ETCP – Displays TCPv4 network errors
# UDP – Displays UDPv4 network traffic
# SOCK6, IP6, EIP6, ICMP6, UDP6 are for IPv6
# ALL – This displays all of the above information. The output will be very long.
# Historic Information
#
# By default, sar will output for the previous 24 hours,
# however previous days can be checked with
sar -f /var/log/sa/sa15 -n DE
# Check Memory usage for yesterday
sar -f /var/log/sa/sa`date --date='-1 day' +'%d'` -r