RHCE (REDHAT7) (iii)

RHCE (REDHAT7)(iii)

First, the configuration of soft RAID (MDADM)

Mdadm system will be installed automatically, do not need additional installation

# mdadm-c/dev/md1-a yes-l1-n2/dev/sdb1/dev/sdb2 ( note 1 is preceded by the letter L,1 represents raid1, 2 for 2 fast drives )

View information:

# mdadm-d/DEV/MD1

generate the configuration file (otherwise, the server restarts the soft RAID is disabled):

# Mdadm-ds >/etc/mdadm.conf

# MKFS.XFS/DEV/MD1

# MOUNT/DEV/MD1/AA (so it can be used, can be written into the/etc/fstab )

Disable Soft RAID:

# mdadm-s/DEV/MD1

Enable Soft RAID:

# mdadm-a/DEV/MD1

Second, Lvm

Create a physical volume group first:

# PVCREATE/DEV/SDB1

Then create a logical volume group:

# vgcreate VG0/DEV/SDB1 (default PE is 4M)

# vgcreate–s 8M vg0/dev/sdb1 (You can specify a PE size of 8M at creation time)

To view the physical Volume Group command:

# Pvscan

To view the logical Volume Group command:

# Vgdisplay Vg0

To delete a physical volume Group command:

# PVREMOVE/DEV/SDB1

To delete a logical Volume Group command:

# Vgremove Vg0

Create a partition of size 200M/dev/vg0/lv01:

# lvcreate–l 200M–N/DEV/VG0/LV01

Create a partition/dev/vg0/lv01(that is, 200x4m)with a size of five PE sizes :

# lvcreate–l 200–N/DEV/VG0/LV01

To view partitions:
# Lvscan

Format the partition ( after mount can be used normally):

# MKFS.XFS/DEV/VG0/LV01

Zoom to 400M:

# lvextend–l 400M–N/DEV/VG0/LV01

added 400M:

# lvextend–l +400M–N/DEV/VG0/LV01

Add a few more PE:

# lvextend–l +50–N/DEV/VG0/LV01

To deactivate a lv01 partition:

# LVCHANGE–AN/DEV/VG0/LV01

reduce partition to 300M(first deactivate partition):

# lvreduce–l 300M–N/DEV/VG0/LV01

Enable lv01 partition:

# LVCHANGE–AY/DEV/VG0/LV01

To add a physical volume:

# Vgextend VG0/DEV/SDB2

To delete a physical volume:

# Vgreduce VG0/DEV/SDB2

Data migration:

# pvmove–i 3/DEV/SDB1/DEV/SDB2 ( sdb1 data is moved to Sdb2 ,3 seconds to refresh once)

Create a snapshot (set the 20% size to Prime ):

# lvcreate–l 40M–N/DEV/VG0/LV01_SNAP–S/DEV/VG0/LV01

To delete a snapshot:

# Lvremove/dev/vg0/lv01_snap

Third, the power-on graphics or text interface

To view the power-on graphics or text:

# Systemctl Get-default

To set the start-Up graphical interface:

# Systemctl Set-default Graphical.target

Or

# Ln–s/usr/systemd/system/graphical.target/etc/system/system/default.target

To set the boot text interface:

# Systemctl Set-default Multi-user.target

Or

# Ln–s/usr/systemd/system/multi-user.target/etc/system/system/default.target

Ctrl+alt+f2....f6 Text Mode

Ctrl+alt+f1\f7 Graphics Mode

Iv. accidental deletion of grub2 directory solutions:

# GRUB2-INSTALL/DEV/SDA

# Grub2-mkconfig >/boot/grub2/grub.cfg

Five, crack root password step:

Method One:

start-up is transferred to Item 2, the letter e in, there will be root=uuid ... Ro of the line,ro back all deleted, add rd.break(only the line portion), and then press ctrl+x

# Mount–o remount,rw/sysroot/

# chroot/sysroot/

# passwd

Enter a new password

# Touch/.autorelabel

# exit

# exit

Method Two:

start-up is transferred to Item 2, the letter e in, there will be root=uuid ... Ro of the line, the last rhgbquiet to Init=/bin/bash, and then press ctrl+x

# Mount–o REMOUNT,RW/

# passwd

Enter a new password

# Touch/.autorelabel

# Exec/sbin/init

Six,systemctl command:

Start, stop, restart, view status:

# Systemctl Start\stop\restart\status httpd

Activation Service:

# Systemctl Is-active httpd

boot httpd:

# Systemctl Enable httpd

Boot does not start httpd:

# systemctl Disable httpd

use the Systemctl command to kill the service:

# Systemctl Kill httpd

List all services (including enable and disable):

# Systemctl List-units--type=service

To block a service (so that it cannot be started or displayed):

# Systemctl Mask httpd

Unblock:

# Systemctl unmask httpd

This article is from the "Linux" blog, so be sure to keep this source http://yangzhiming.blog.51cto.com/4849999/1718494

RHCE (REDHAT7) (iii)