System File Checks

Question 1

lsblk -f

blkid

Answer 1

To get labels and UUIDs
Use -f

Non GPT
Shows device name, label name, UUID etc. great when you need more information than device name. Easier to read for device name too.
To add these to fstab file, we need to call those with GPT Label: PARTLABEL=[partition label]

blkid
For GPT
To add these to fstab file, we need to call those with GPT UUID: PARTUUID=[partition UUID label]

Question 2

fstab

Answer 2

File in /etc/fstab
Can add drives to this to auto mount them on boot.

Shows drives, mount locations and file system types

can be safely viewed using the cat command
cat /etc/fstab

Most versions of Linux will use ext2, 3, 4.
3 & 4 are identical except, ext3 has journalling enabled. Ext4 is an improvement on that.

FS Auto - Rare to see, but it mounts it automatically. Only really okay for read only media like a CD-ROM drive. File checks can actually damage file systems when they are unknown.

plus dump and pass info for backing up and file checks on boot?

Question 3

tunefs -L Sales /dev/vg1/Sales

Answer 3

Labeling

Question 4

Dump

Answer 4

Dump column used to use the dump program to backup on reboot if 1 in the dump column.
Second to last column with long form

0= do not backup
1= perform backup

Question 5

Pass

Answer 5

Pass column used to do a filesystem check during boot. Sets priority of scan

0 = don’t run filesystem check

1 = high priority filesystem check (get checked first)

2 = low priority filesystem check (get checked second so the system can continue to boot while these are checked)

Question 6

UUID

Answer 6

Universally unique identifier
Aka GUID - Globally unique identifier

Used to identify partitions and as identity information in computer systems.

Question 7

Drive options

auto/noauto

Answer 7

Options

auto/noauto - Automatically mount at boot time

Question 8

user/nouser

Answer 8

• Allow non-root users to mount

Question 9

exec/noexec - Allow executables

Answer 9

1

Question 10

ro - Mount read-only

Answer 10

1

Question 11

rw - Mount read-write

Answer 11

1

Question 12

sync/async - Perform disk I/O

Answer 12

1

Question 13

synchronous or asynchronous
Sync - Commands wait for writes to complete
Async - Commands terminate prior to writes completing

Answer 13

1

Question 14

dev/nodev - Allow block devices (/dev/*)

Answer 14

1

Question 15

usrquota/grpquota - Enable user/group quotas

Answer 15

1

Question 16

suid - Allow the use of SetUID/SetGID

Answer 16

1

Question 17

defaults - rw,suid,dev,exec,auto,nouser,asyn

Answer 17

Default settings as default options for drives

Question 18

df -h

du

Answer 18

df to look at the disk as a whole
-h Shows human readable data (GBs and MBs)

du to look at the folders inside that disk

Question 19

fsck -A

fsck -t ext2 /dev/sda2

Answer 19

fsck
FileSystem ChecK - checks file system for errors
the front end for the various filesystem tools

-A checks all filesystems

-t ext2 specifies filesystem type
/dev/sda2 is the specified drive

other examples:
e2fsck checks ext2/ext3 filesystems

To scan root drive:
Requires changes to fstab file and a reboot is required.
OR
Run a USB live Linux OS and scan the primary drive with fsck

Question 20

mkfs

Answer 20

Builds a linux filesystem
Formats ext2/ext3/ext4

Front end for format utilities

mke2fs similar but for ext

Question 21

debugfs

Answer 21

Special filesystem that resides in RAM

Useful for troubleshooting tools

Question 22

dumpe2fs

Answer 22

Prints out filesystem information

example:
dumpe2fs -h /dev/sda1
human readable

Question 23

tune2fs

Answer 23

tune the performance of a filesystem

change # of mounts between filesystem integrity checks
example:
tune2fs -c 60 -i 6m /dev/sda1
(60 mounts, 6 months)

Change a volume’s name

tune2fs -L Storage /dev/sdb1
tune2fs -l /dev/sda1 | grep volume

Convert ext2 to ext3

Enables journaling
tune2fs -j /dev/sdc1

Question 24

How should you use fsck to check the root drive on a CentOS server you have physical access to?

Answer 24

Run a USB live Linux OS and scan the primary drive with fsck

fsck -y /dev/[sda where OS is installed]