DO316 - ch05s04

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Guided Exercise: Attach and Access Disks on Virtual Machines

A new MariaDB VM is provisioned with a boot disk and a single 15 GB data disk. To ensure performance, you must separate database data files, transaction logs, and undo files onto their own disks. You add a new disk for each file type, point MariaDB to the appropriate disk for each type, and then delete the old disk to reclaim your storage.

Outcomes

Create disks with specific requirements.
Attach disks to existing VMs.
Detach disks from VMs.
Delete disks.

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

This command ensures that the cluster API is reachable. The command also creates the storage-multiple namespace and starts the mariadb-server VM in that namespace.

[student@workstation ~]$ lab start storage-multiple

Instructions

As the admin user, locate and then navigate to the OpenShift web console. Confirm that the mariadb-server VM is running.
1. From a terminal, log in to your Red Hat OpenShift cluster as the admin user.
```
[student@workstation ~]$ oc login -u admin -p redhatocp \
  https://api.ocp4.example.com:6443
Login Successful
...output omitted...
```
2. Identify the URL for the OpenShift web console.
```
[student@workstation ~]$ oc whoami --show-console
https://console-openshift-console.apps.ocp4.example.com
```
3. Open a web browser and navigate to the web console URL: https://console-openshift-console.apps.ocp4.example.com
  Select htpasswd_provider and log in as the admin user with redhatocp as the password.
Confirm that only the vda, vdb, and vdc disks are attached to the VM.
1. Navigate to Virtualization → VirtualMachines. Select the storage-multiple project. Confirm that the mariadb-server VM is running.
2. Click the VM name and navigate to the Console tab. Log in as the root user with redhat as the password. Run the lsblk command to list the block devices.
```
[root@mariadb-server ~]# lsblk
NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
vda    252:0    0   10G  0 disk
├─vda1 252:1    0    1M  0 part
├─vda2 252:2    0  100M  0 part /boot/efi
└─vda3 252:3    0  9.9G  0 part /
vdb    252:16   0    1M  0 disk
vdc    252:32   0 14.2G  0 disk
```
3. Navigate to the Configuration → Disks tab. Notice that the storage class for the dbroot disk is nfs-storage, which is using slow NFS shares as back-end storage. The MariaDB server uses that dbroot disk to store the database files.
4. Confirm that the database service is working correctly and that you can access the sakila database.
```
[root@mariadb-server ~]# mysql -u devuser -p'developer' sakila
...output omitted...
MariaDB [sakila]> SHOW TABLES;
+----------------------------+
| Tables_in_sakila           |
+----------------------------+
...output omitted...
+----------------------------+
23 rows in set (0.001 sec)

MariaDB [sakila]> quit
Bye
```
5. Log out of the VM console.
```
[root@mariadb-server ~]# logout
```

Create and attach three 5 GiB disks to the mariadb-server VM. Use the fast ocs-external-storagecluster-ceph-rbd-virtualization storage class in Block mode. Preallocate the space for improving write performance. Use the VirtIO interface to connect the disks to the VM.

Stop the mariadb-server VM to attach more disks. From the OpenShift web console, select the mariadb-server VM and then click Actions → Stop. Click Stop to confirm the operation, if needed.

Navigate to the Configuration → Disks tab. Click Add disk to create and attach the dbdata disk. Complete the form by using the following information and click Add to create and attach the disk to the VM.

Repeat this step for the dbredo and dbundo disks. You configure that disk for the MariaDB Server data files in another step.

Note

If the Interface field is set to SCSI and VirtIO is not available, then click Cancel and start over. The web interface takes a few seconds to detect that the VM is stopped.

Field	Value
Use this disk as a boot source	Unset
Name	`dbdata` `dbredo` `dbundo`
Source	Blank (creates PVC)
Size	5 GiB
Type	Disk
Interface	VirtIO
StorageClass	`ocs-external-storagecluster-ceph-rbd-virtualization`
Apply optimized StorageProfile settings	Checked
Access mode	Shared access (`RWX`)
Volume mode	Block
Enable preallocation	Checked

Wait until OpenShift finishes the provisioning of the VM disks and the Pending changes admonition is not displayed.
Click Actions → Start to start the VM and wait until it is running.

Log in to the VM console and confirm that three new 5 GiB devices are available. Navigate to the Console tab and then log in as the root user with redhat as the password. Run the lsblk command to list the block devices. Notice the three 5 GiB block devices.

[root@mariadb-server ~]# lsblk
NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
vda    252:0    0   10G  0 disk
├─vda1 252:1    0    1M  0 part
├─vda2 252:2    0  100M  0 part /boot/efi
└─vda3 252:3    0  9.9G  0 part /
vdb    252:16   0    1M  0 disk
vdc    252:32   0 14.2G  0 disk
vdd    252:48   0    5G  0 disk	
vde    252:64   0    5G  0 disk	
vdf    252:80   0    5G  0 disk

	The `vdd` device corresponds to the `dbdata` disk.
	The `vde` device corresponds to the `dbredo` disk.
	The `vdf` device corresponds to the `dbundo` disk.

The lab command prepared the /root/dbmove.sh script to format the three disks and then move the database files to these disks. Run the script to migrate the MariaDB server data.

From the mariadb-server VM console, run the script:

[root@mariadb-server ~]# ~/dbmove.sh
...output omitted...

Confirm that the database service is working correctly and that you can access the sakila database.

[root@mariadb-server ~]# mysql -u devuser -p'developer' sakila
...output omitted...
MariaDB [sakila]> SHOW TABLES;
+----------------------------+
| Tables_in_sakila           |
+----------------------------+
...output omitted...
+----------------------------+
23 rows in set (0.001 sec)

MariaDB [sakila]> quit
Bye

Log out of the VM console.
```
[root@mariadb-server ~]# logout
```

Detach and then delete the dbroot disk. The MariaDB server stored its data on that disk before you moved the data to the three new disks.
1. Click Actions → Stop to stop the VM, and wait for the machine to stop.
2. Navigate to the Configuration → Disks tab. Click the vertical ellipsis icon ⋮ to the right of the dbroot disk and then click Detach. In the confirmation window, click Detach to confirm.
3. Click Actions → Start, and wait until the VM is running.
4. Log in to the VM console and confirm that the 15 GiB device is no longer shown. Navigate to the Console tab and then log in as the root user with redhat as the password. Run the lsblk command to list the block devices. Notice that the deleted 15 GiB block device is no longer listed.
```
[root@mariadb-server ~]# lsblk
NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
vda    252:0    0   10G  0 disk
├─vda1 252:1    0    1M  0 part
├─vda2 252:2    0  100M  0 part /boot/efi
└─vda3 252:3    0  9.9G  0 part /
vdb    252:16   0    1M  0 disk
vdc    252:32   0    5G  0 disk /mariadb/data
vdd    252:48   0    5G  0 disk /mariadb/redo
vde    252:64   0    5G  0 disk /mariadb/undo
```
5. Log out of the VM console.
```
[root@mariadb-server ~]# logout
```

Finish

On the workstation machine, 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 storage-multiple

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11 sie 2023

We are excited to launch a space dedicated to the Red Hat Training course, Managing Virtual Machines with Red Hat OpenShift Virtualization! To gain the most value from this group - click the "Join Group" button in the upper right hand corner of the group home page.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 DO316.Read more about Managing Virtual Machines with Red Hat OpenShift Virtualization here.

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Revision: do316-4.14-d8a6b80