Hardware Troubleshooting

Question 1

How list hardware seen by computer?

Answer 1

• lspci (list PCI devices)
• lsblk (list block devices - doesn’t include ram devices)
• lscpu (lists CPU info)
• lsscsi (lists SCSI info)

Question 2

How check status of daemons running?

Answer 2

systemctl status

# systemctl start [name.service]
 # systemctl stop [name.service] 
# systemctl restart [name.service] 
# systemctl reload [name.service] 
$ systemctl status [name.service]
 # systemctl is-active [name.service] 
$ systemctl list-units --type service --

Question 3

Where look for error messages?

Answer 3

-dmesg (display message/driver message)

  dmesg displays messages from kernel ring buffer. Can view messages about specific devices like:
#dmesg | grep -i memory
# dmesg | grep -i dma
# dmesg | grep -i usb
# dmesg | grep -i tty
Thedmesgmessages are grouped into categories called “facilities.” The list of facilities is:

kern: Kernel messages.
user: User-level messages.
mail: Mail system.
daemon: System daemons.
auth: Security/authorization messages.
syslog: Internal syslogd messages.
lpr: Line printer subsystem.
news: Network news subsystem.

We can askdmesgto filter its output to only show messages in a specific facility. To do so, we must use the-f(facility) option:

sudo dmesg -f daemon

-other logs in /var/log

Question 4

How find IP/Network status?

Answer 4

• ifconfig
• ip addr show
• ip link

Question 5

How look at network connectivity issues?

Answer 5

• ping
• traceroute
• nslookup

Question 6

How test RAM?

Answer 6

• memtest86+ (can be installed using yum)

- memtester

Question 7

How stress test CPU/RAM?

Answer 7

-“stress” (yum instal from EPEL repo)

Question 8

What is OpenBMC?

Answer 8

BMC is Baseboard Management Controller. For context, a BMC is a specialized controller embedded in servers. It often comes in the form of a system-on-chip (SoC), with its own CPU, memory, and storage and lots of IO. A BMC connects to sensors to read environmental conditions and to fans to control temperature. It also provides other system management functions, including remote power control, serial over LAN, and monitoring and error logging of the server host CPU and memory.

Question 9

A utility to check memory controller error detection

Answer 9

• edac-util - The default edac-util report is generated when the program is run without any options. If there are no errors logged by EDAC, this report will display “No errors to report.” to stdout. Otherwise, error counts for each MC, csrow, channel combination with attributed errors are displayed, along with corresponding DIMM labels, if these labels have been registered in sysfs.

Question 10

What is IPMI?

Answer 10

Intelligent Platform Management Interface. Send to work on top of BMC built into motherboards.

Question 11

how find make/model of storage drives?

Answer 11

First, you need the device names of your disks, for this you can use df or cat /proc/partitions:

• hdparm -i (device_name) (i.e /dev/sda)
• lshw -class disk
• smartctl -i /dev/sda
• hwinfo –disk
• ls /dev/disk/by-id

Question 12

how check network card/device status?

Answer 12

• ipconfig
• up link
• cat /proc/net/dev

Question 13

how find make/model of NIC?

Answer 13

• lspci | egrep -i –color ‘network|ethernet’
• lshw -class network
  (other “class” options for lshw:
  address
  bridge
  bus
  communication
  disk
  display
  generic
  input
  memory
  multimedia
  network
  power
  printer
  processor
  storage
  system
  tape
  volume
  )