# Diagnostic commands
Bunch of useful commands for checking your system.
# Megaraid
# Get raid data
MegaCli -CfgDsply -aAll; MegaCli -LDInfo -LAll -aAll; MegaCli -PdList -aALL | egrep "Slot|Device Id|Inquiry Data"
# Smartctl
Smartctl commands for checking the health of disks
# Install smartctl
apt-get install -y smartmontools
# Using sda/sdb/sdc
Regular disks with the sda/sdb/sdc naming convention
for i in /dev/sd?; do echo "$i"; smartctl -a "$i"; echo; done
# Using Megaraid
Disks connected via a Megaraid controller
smartctl --scan | grep "megaraid," | awk '{ print $3 }' | sed -r 's/.*,([0-9]*)/\1/g' | while read x; do echo Device $x;smartctl -a -d megaraid,$x /dev/sda; done
# Using LSI Megaraid
Disk that require the storcli command. This assumes that the raid disk is being presented as /dev/sda
storcli /call /dall show | awk '{ print $5 }' | grep -E "[0-9]{1,2}" | while read x; do echo Device $x;smartctl -a -d sat+megaraid,$x /dev/sda; done
# Using NVMe
nvme list && echo && for i in /dev/nvme?n1; do echo "$i"; nvme smart-log "$i"; nvme smart-log-add "$i"; echo; done
# FIO
Testing disk iops
# Install fio first
apt-get install -y fio
# Write test
Fixed runtime of 120 seconds
fio --name=rand-write --ioengine=libaio --iodepth=32 --rw=randwrite --invalidate=1 --bsrange=4k:4k,4k:4k --size=512m --runtime=120 --time_based --do_verify=1 --direct=1 --group_reporting --numjobs=1
# Read test
Fixed runtime of 120 seconds
fio --name=rand-read --ioengine=libaio --iodepth=32 --rw=randread --invalidate=1 --bsrange=4k:4k,4k:4k --size=512m --runtime=120 --time_based --do_verify=1 --direct=1 --group_reporting --numjobs=1
# Read/Write test - 2 Mins
Fixed runtime of 120 seconds
fio --name=rand-rw --ioengine=libaio --iodepth=32 --rw=randrw --invalidate=1 --bsrange=4k:4k,4k:4k --size=512m --runtime=120 --time_based --do_verify=1 --direct=1 --group_reporting --numjobs=1
# Read/Write test - 4GB
Creates a 4GB file in the current directory to test with
fio --name=test --ioengine=libaio --iodepth=64 --rw=randrw --gtod_reduce=1 --filename=test --bs=4k --size=4G --rwmixread=75 --randrepeat=1 --direct=1
# lm-sensors
Utility for checking the temperature sensors of your machine.
# Install lm-sensors
apt-get update
apt-get install -y lm-sensors
Run the following command (Answer Y to all prompts):
sensors-detect
Finally, run the following command:
sensors
# Process Tree
Useful for finding out what started a process on your system.
ps auxf
# List Network Ports
Alternative to netstat
ss -tulpn
-t - TCP
-u - UDP
-l - Listening
-p - Process
-n - Do not resolve hostnames
# NTP Stuff
# Force Check
CentOS6
service ntpd stop; ntpd -gq; service ntpd start
OS not in the stone age
systemctl stop ntpd; ntpd -gq; systemctl start ntpd
# Useful commands
Show sync status
ntpstat
Force a sync
ntpd -gq
-g ignore large time differences
-q exit ntpd after (otherwise it carries on running)
Show peers
ntpq -p
Query a server
ntpdate -q pool.ntp.org
# Yum
Issues with updating using Yum can be due to:
- Time/Date setting
- Out of date certificates
Example error:
Error: Cannot retrieve metalink for repository: epel. Please verify its path and try again
sudo yum clean all
sudo yum --disablerepo="epel" update nss ca-certificates
sudo yum makecache
sudo yum update
# Delete dmraid Metadata
DEVICE=/dev/sda
dd if=/dev/zero of=$DEVICE bs=512 seek=$(( $(blockdev --getsz $DEVICE) - 1024 )) count=1024
# Curl Tricks
# Use different IP for domain
This is used instead of changing the host header.
curl -vI --resolve custom.domain.com:443:192.168.1.101 https://custom.domain.com
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