Exercise: Managing storage

Managing storage

• Use the storage system role to create, format and persistently mount LVM volumes.

Prerequisites: Complete control-node setup and the preceding lessons in this chapter. Run commands as student on workstation unless a step names another machine.

From the project directory, run the relevant home-lab check. For an exercise with several checkpoints, grade each state before changing or removing it:

lab grade system-storage

The grader reads project files and host state. A passing report covers the listed checks; also perform the task’s independent connection, repeat-run, and reboot checks where requested.

After a clean VM and data-volume reset, choose different volume names and update the mount verification.

Record the published result first. The grader checks the original requirements, so a changed name or value may intentionally fail those checks.

Provide persistent, separate web-content and web-log filesystems on servera using storage.yml and the storage system role.

• Use the confirmed empty extra disk: /dev/sdb at home, /dev/vdb in the classroom. Preserve the root disk.
• Volume group apache-vg must contain content-lv (512 MiB) and logs-lv (768 MiB), both XFS.
• Mount them persistently on /var/www and /var/log/httpd respectively.
• Verify every storage layer, repeat without unintended changes, and check mounts after an explicit reboot.

The spare disk in the home lab is /dev/sdb, not /dev/vdb: use sdb wherever the steps say vdb. lab start system-storage packages the system roles collection installed on workstation as redhat-rhel_system_roles-1.120.5.tar.gz (your version may differ).

The requirements

On servera:

• /dev/vdb is the physical volume of a volume group apache-vg,
• two logical volumes in it: content-lv, 512 MiB, and logs-lv, 768 MiB,
• both formatted with XFS,
• content-lv mounted persistently on /var/www, and logs-lv on /var/log/httpd.

Install the collection into the project

[student@workstation ~]$ cd ~/system-storage
[student@workstation system-storage]$ ansible-galaxy collection install \
> ./redhat-rhel_system_roles-1.120.5.tar.gz -p collections
...output omitted...
redhat.rhel_system_roles:1.120.5 was installed successfully

Describe the storage

Create storage.yml. One play for webservers applies the storage role, with a storage_pools entry for the volume group and its two volumes:

---
- name: Configure storage on webservers
  hosts: webservers

  roles:
    - name: redhat.rhel_system_roles.storage
      storage_pools:
        - name: apache-vg
          type: lvm
          disks:
            - /dev/vdb
          volumes:
            - name: content-lv
              size: 512m
              mount_point: "/var/www"
              fs_type: xfs
              state: present
            - name: logs-lv
              size: 768m
              mount_point: "/var/log/httpd"
              fs_type: xfs
              state: present

The variables are passed as role parameters. On older cores, role variables can also be visible elsewhere in the play; use names prefixed for the role to avoid collisions. There is no task for the physical volume, the file systems or /etc/fstab: the role works those out from the description.

Run it

[student@workstation system-storage]$ ansible-navigator run -m stdout storage.yml
...output omitted...
TASK [redhat.rhel_system_roles.storage : Make sure blivet is available] ********
changed: [servera.lab.example.com]
...output omitted...
TASK [redhat.rhel_system_roles.storage : Set up new/current mounts] ************
changed: [servera.lab.example.com] => (item={'src': '/dev/mapper/apache--vg-content--lv', 'path': '/var/www', 'fstype': 'xfs', 'opts': 'defaults', 'dump': 0, 'passno': 0, 'state': 'mounted', ...})
changed: [servera.lab.example.com] => (item={'src': '/dev/mapper/apache--vg-logs--lv', 'path': '/var/log/httpd', 'fstype': 'xfs', 'opts': 'defaults', 'dump': 0, 'passno': 0, 'state': 'mounted', ...})
...output omitted...
PLAY RECAP *********************************************************************
servera.lab.example.com    : ok=24   changed=4    unreachable=0    failed=0    skipped=13  ...

The role first installs blivet, the storage library it works with, then builds the stack. Run it again: changed=0.

Inspect the result

[student@workstation system-storage]$ ansible-navigator run -m stdout get-storage.yml
...output omitted...
TASK [Display physical volumes] ************************************************
ok: [servera.lab.example.com] => {
    "msg": [
        "  PV         VG        Fmt  Attr PSize  PFree ",
        "  /dev/sdb   apache-vg lvm2 a--  <5.00g <3.75g"
    ]
}
...output omitted...
TASK [Display logical volumes] *************************************************
ok: [servera.lab.example.com] => {
    "msg": [
        "  LV         VG        Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert",
        "  content-lv apache-vg -wi-ao----  512.00m                                                    ",
        "  logs-lv    apache-vg -wi-ao---- 768.00m                                                    "
    ]
}
...output omitted...
TASK [Display mounted logical volumes] *****************************************
ok: [servera.lab.example.com] => {
    "msg": [
        "/dev/mapper/apache--vg-content--lv on /var/www type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,noquota)",
        "/dev/mapper/apache--vg-logs--lv on /var/log/httpd type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,noquota)"
    ]
}
...output omitted...
TASK [Display /etc/fstab contents] *********************************************
ok: [servera.lab.example.com] => {
    "msg": [
...output omitted...
        "# system_role:storage",
        "/dev/mapper/apache--vg-content--lv /var/www xfs defaults 0 0",
        "/dev/mapper/apache--vg-logs--lv /var/log/httpd xfs defaults 0 0"
    ]
}

The disk sizes depend on your lab. Every layer is there, and the mounts are in /etc/fstab, marked by the role.

Finish

Check your work with lab grade system-storage, then put the exercise away with lab finish system-storage.