Linux Performance Analysis - USE Method

USE Method (by Brendan Gregg)

For every resource, check utilization, saturation, and errors.

Resource: all physical server functional components (CPUs, disks, busses, ...)
Utilization: the average time that the resource was busy servicing work
Saturation: the degree to which the resource has extra work which it can't service, often queued
Errors: the count of error events


--Quick Check

Check system resource usage and running processes by running the ten commands
# uptime
# dmesg | tail
# vmstat 1
# mpstat -P ALL 1
# pidstat 1
# iostat -xz 1
# free -m
# sar -n DEV 1
# sar -n TCP,ETCP 1
# top


--Logs Check

Common logs location
/var/log/auth.log : Authentication logs
/var/log/secure or /var/log/auth.log : Authentication log
/var/log/messages : General message and system related stuff
/var/log/kern.log : Kernel logs
/var/log/cron.log : Crond logs (cron job)
/var/log/maillog : Mail server logs
/var/log/qmail/ : Qmail log directory (more files inside this directory)
/var/log/httpd/ : Apache access and error logs directory
/var/log/lighttpd/ : Lighttpd access and error logs directory
/var/log/boot.log : System boot log
/var/log/mysqld.log : MySQL database server log file
/var/log/utmp or /var/log/wtmp : Login records file
/var/log/yum.log : Yum command log file.

# less /var/log/messages
# more /var/log/messages

Continuous log fail observation
#tail -f /var/log/messages

Search  for a term in a file
#grep -i error /var/log/messages


--Services check

Show all installed services
#systemctl list-unit-files

#service --status-all
#service --status-all | more
#service --status-all | less
#service --status-all | grep ntpd


--System info check

Show version
#lsb_release -a

# lshw
# lscpu
# lsblk
# lspci
# fdisk -l

Show kernel  modules
#lsmod

List containing your BIOS version and supported modes, your motherboard manufacturer and model number, your CPU technical details and your RAM characteristics
#sudo dmidecode -q 


Microsoft Automatic Private IP Addressing (APIPA) - 169.254.0.1-169.254.255.254

Have you ever get PC automatically change to 169.x.x.x?

If yes, maybe it's because of the APIPA (Microsoft Automatic Private IP Addressing).
When the DHCP server was crash and when the client don't get any IP address from the server, APIPA assign a random IP address from the range 169.254.0.1 through 169.254.255.254 to the host.

Disable APIPA

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces subkey. 

Select the string that identifies your adapter, and create a new DWORD Value.
Name the entry IPAutoconfigurationEnabled, and set the value to 0.
If you have multiple adapters, repeat the process for each adapter under the Interfaces subkey

CCTV - Maximum Cable Length for Analog CCTV

Based on my experience, we can use;

- Cat5e can be used for Video and Power on same time (in one cable) with maximum range 250 ft.

- If more than 250 ft, Cat5e that we use must seperate the video and power cable

- Volt and Amp can't be to low or to high, it'll impact the video quality

...

(250 ft = 75 m)