RH134 - ch08s02

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Guided Exercise: Create and Extend Logical Volumes

In this lab, you create and extend a physical volume, volume group, logical volume, and an XFS file system. You also persistently mount the logical volume file system.

Outcomes

Create physical volumes, volume groups, and logical volumes with LVM tools.
Create file systems on logical volumes and persistently mount them.
Extend the volume group to include an additional physical volume.
Resize the logical volume when the file system is still mounted and in use.

As the student user on the workstation machine, use the lab command to prepare your system for this exercise.

This command prepares your environment and ensures that all required resources are available.

[student@workstation ~]$ lab start lvm-manage

Instructions

[student@workstation ~]$ ssh student@servera
...output omitted...
[student@servera ~]$ sudo -i
[sudo] password for student: student
[root@servera ~]#

Create the physical device partition on the /dev/vdb storage device.

Create two partitions of 256 MiB each and set to the Linux LVM type. Use the first and second names for these partitions.

[root@servera ~]# parted /dev/vdb mklabel gpt
Information: You may need to update /etc/fstab.

[root@servera ~]# parted /dev/vdb mkpart first 1MiB 258MiB
Information: You may need to update /etc/fstab.

[root@servera ~]# parted /dev/vdb set 1 lvm on
Information: You may need to update /etc/fstab.

[root@servera ~]# parted /dev/vdb mkpart second 258MiB 514MiB
Information: You may need to update /etc/fstab.

[root@servera ~]# parted /dev/vdb set 2 lvm on
Information: You may need to update /etc/fstab.

List the partitions on the /dev/vdb storage device. In the Number column, the 1 and 2 values correspond to the /dev/vdb1 and /dev/vdb2 device partitions. The Flags column indicates the partition type.

[root@servera ~]# parted /dev/vdb print
Model: Virtio Block Device (virtblk)
Disk /dev/vdb: 5369MB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:

Number  Start   End    Size   File system  Name    Flags
 1      1049kB  271MB  269MB               first   lvm
 2      271MB   539MB  268MB               second  lvm

Label the two new partitions as physical volumes.

[root@servera ~]# pvcreate /dev/vdb1 /dev/vdb2
  Physical volume "/dev/vdb1" successfully created.
  Physical volume "/dev/vdb2" successfully created.
  Creating devices file /etc/lvm/devices/system.devices

Create the servera_group volume group by using the two new PVs.

[root@servera ~]# vgcreate servera_group /dev/vdb1 /dev/vdb2
  Volume group "servera_group" successfully created

Create the servera_volume logical volume with a size of 400 MiB. This command creates the /dev/servera_group/servera_volume LV without a file system.
```
[root@servera ~]# lvcreate -n servera_volume -L 400M servera_group
  Logical volume "servera_volume" created.
```
Format the newly created LV and mount it persistently.
1. Format the servera_volume LV with the XFS file system.
```
[root@servera ~]# mkfs -t xfs /dev/servera_group/servera_volume
...output omitted...
```
2. Create the /data directory as a mount point.
```
[root@servera ~]# mkdir /data
```
3. To persistently mount the newly created file system, add the following content in the /etc/fstab file:
```
/dev/servera_group/servera_volume /data xfs defaults 0 0
```
4. Mount the servera_volume LV.
```
[root@servera ~]# mount /data
```

Verify that the mounted file system is accessible, and display the status information of the LVM.

Verify that you can copy files to the /data directory.

[root@servera ~]# cp -a /etc/*.conf /data
[root@servera ~]# ls /data | wc -l
32

View the PV status information. The output shows that the PV uses the servera_group VG. The PV has a size of 256 MiB and a physical extent size of 4 MiB.
The VG contains 63 PEs, of which 27 PEs are available for allocation, and 36 PEs are currently allocated to LVs. Use the following calculation for allocating the volume size in MiBs:
- Total 252 MiB (63 PEs x 4 MiB)
- Free 108 MiB (27 PEs x 4 MiB)
- Allocated 144 MiB (36 PEs x 4 MiB)
```
[root@servera ~]# pvdisplay /dev/vdb2
  --- Physical volume ---
  PV Name               /dev/vdb2
  VG Name               servera_group
  PV Size               256.00 MiB / not usable 4.00 MiB
  Allocatable           yes
  PE Size               4.00 MiB
  Total PE              63
  Free PE               27
  Allocated PE          36
  PV UUID               FKKFYJ-wJiR-1jt2-sfy3-yjPy-TylN-LG92jj
```

View the VG status information of the servera_group VG. The output shows a VG size of 508 MiB with a PE size of 4 MiB. The available size from the VG is 108 MiB.

[root@servera ~]# vgdisplay servera_group
  --- Volume group ---
  VG Name               servera_group
  System ID
  Format                lvm2
  Metadata Areas        2
  Metadata Sequence No  2
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                1
  Open LV               1
  Max PV                0
  Cur PV                2
  Act PV                2
  VG Size               508.00 MiB
  PE Size               4.00 MiB
  Total PE              127
  Alloc PE / Size       100 / 400.00 MiB
  Free  PE / Size       27 / 108.00 MiB
  VG UUID               g0ahyT-90J5-iGic-nnb5-G6T9-tLdK-dX8c9M

View the status information for the servera_volume LV. The output shows the VG name for creating the LV. It also shows an LV size of 400 MiB and an LE size of 100.

[root@servera ~]# lvdisplay /dev/servera_group/servera_volume
  --- Logical volume ---
  LV Path                /dev/servera_group/servera_volume
  LV Name                servera_volume
  VG Name                servera_group
  LV UUID                93MfUt-esgT-B5HM-r1p5-DVZH-n5cn-J5e2tw
  LV Write Access        read/write
  LV Creation host, time servera.lab.example.com, 2022-04-11 03:25:12 -0400
  LV Status              available
  # open                 1
  LV Size                400.00 MiB
  Current LE             100
  Segments               2
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:0

View the free disk space in human-readable units. The output shows the total size of 395 MiB with the available size of 372 MiB.

[root@servera ~]# df -h /data
Filesystem                               Size  Used Avail Use% Mounted on
/dev/mapper/servera_group-servera_volume  395M   24M  372M   6% /data

Create the physical resource on the /dev/vdb storage device.
1. Create an additional partition of 512 MiB and set it to the Linux LVM type. Use the third name for this partition.
```
[root@servera ~]# parted /dev/vdb mkpart third 514MiB 1026MiB
[root@servera ~]# parted /dev/vdb set 3 lvm on
```
2. Register the new partition with the kernel.
```
[root@servera ~]# udevadm settle
```
3. Add the new partition as a PV.
```
[root@servera ~]# pvcreate /dev/vdb3
  Physical volume "/dev/vdb3" successfully created.
```

Using the newly created disk space, extend the file system on the servera_volume to be a total size of 700 MiB.

Extend the servera_group VG by using the new /dev/vdb3 PV.

[root@servera ~]# vgextend servera_group /dev/vdb3
  Volume group "servera_group" successfully extended

Extend the existing servera_volume LV to 700 MiB.

[root@servera ~]# lvextend -L 700M /dev/servera_group/servera_volume
  Size of logical volume servera_group/servera_volume changed from 400.00 MiB (100 extents) to 700.00 MiB (175 extents).
  Logical volume servera_group/servera_volume successfully resized.

Extend the XFS file system by using the free space on the LV.

[root@servera ~]# xfs_growfs /data
...output omitted...
data blocks changed from 102400 to 179200

Verify that the LV size is extended, and that the contents are still present in the volume.

Verify the size of the extended LV by using the lvdisplay command.

[root@servera ~]# lvdisplay /dev/servera_group/servera_volume
  --- Logical volume ---
  LV Path                /dev/servera_group/servera_volume
  LV Name                servera_volume
  VG Name                servera_group
  LV UUID                mLQhsD-hyL0-KC2B-2nug-o2Nc-0znS-Q428fK
  LV Write Access        read/write
  LV Creation host, time servera.lab.example.com, 2022-04-12 06:04:12 -0400
  LV Status              available
  # open                 1
  LV Size                700.00 MiB
  Current LE             175
  Segments               3
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:0

Verify the new file-system size. Verify that the previously copied files are still present.

[root@servera ~]# df -h /data
Filesystem                               Size  Used Avail Use% Mounted on
/dev/mapper/servera_group-servera_volume  695M   26M  670M   4% /data
[root@servera ~]# ls /data | wc -l
32

Return to the workstation machine as the student user.

[root@servera ~]# exit
logout
[student@servera ~]$ exit
logout
Connection to servera closed.

Finish

On the workstation machine, change to the student user home directory and use the lab command to complete this exercise. This step is important to ensure that resources from previous exercises do not impact upcoming exercises.

[student@workstation ~]$ lab finish lvm-manage

This concludes the section.

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Is It possible to reset root password when the system is on multi-user.target?

jennifer1987

27 lip 2023

Hi thereWell, i have a question, Is It possible to reset root password when the system is on multi-user.target? I was not be able to found a foro o some information related with this and another question that I have, If the grub menu dont show up, is it posible to reset the root password?

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Red Hat System Administration II (RH134)

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21 lip 2023

Build the skills to perform the key tasks needed to become a full-time Linux administratorRed Hat System Administration II (RH134) is the second part of the RHCSA training track for IT professionals who have already attended Red Hat System Administration I. The course goes deeper into core Linux system administration skills in storage configuration and management, installation and deployment of Red Hat Enterprise Linux, management of security features such as SELinux, control of recurring system tasks, management of the boot process and troubleshooting, basic system tuning, and command-line automation and productivity. This course assumes that students have attended Red Hat System Administration I (RH124).Experienced Linux administrators who seek rapid preparation for the RHCSA certification should instead start with RHCSA Rapid Track (RH199).This course is based on Red Hat Enterprise Linux 9.0.Course summaryInstall Red Hat Enterprise Linux using scalable methodsAccess security files, file systems, and networksExecute shell scripting and automation techniquesManage storage devices, logical volumes, and file systemsManage security and system accessControl the boot process and system servicesRun containersAudience for this courseThis course is geared toward Windows system administrators, network administrators, and other system administrators who are interested in supplementing current skills or backstopping other team members, in addition to Linux system administrators who are responsible for these tasks:Configuring, installing, upgrading, and maintaining Linux systems using established standards and proceduresProviding operational supportManaging systems for monitoring system performance and availabilityWriting and deploying scripts for task automation and system administrationRecommended trainingSuccessful completion of Red Hat System Administration I (RH124) is recommended.Experienced Linux administrators seeking to accelerate their path toward becoming a Red Hat Certified System Administrator should start with the RHCSA Rapid Track course (RH199).Take our free assessment to gauge whether this offering is the best fit for your skills.Technology considerationsThere are no special technology requirements.This course is not designed for bring your own device (BYOD).Internet access is not required, but is recommended to allow students to research and access Red Hat online resources.

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We are excited to launch a space dedicated to the Red Hat Training course Red Hat System Administration II! To gain the most value from this group - click the "Join Group" button in the upper right hand corner.We encourage group members to collaborate in this group to discuss topics, ask questions, share best practices and tips, provide course feedback, and share their accomplishments as it relates to RH134.Read more about Red Hat System Administration II here.

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