DO316 - ch05s06

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Guided Exercise: Connect Virtual Machines to External Storage

Add a data disk to a MariaDB VM over iSCSI to accommodate a new database. Use a dedicated data disk from your SAN with iSCSI.

Outcomes

Create a Persistent Volume to declare an iSCSI target.
Create a Persistent Volume Claim and attach it as a VM disk.

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-external namespace and starts a virtual machine named mariadb-server in that namespace.

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

Instructions

As the admin user, locate and then navigate to the OpenShift web console. Confirm that the mariadb-server VM is running.
1. From the command line, log in to your Red Hat OpenShift cluster as the admin user.
```
[student@workstation ~]$ oc login -u admin -p redhat \
  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 https://console-openshift-console.apps.ocp4.example.com. Select htpasswd_provider and log in as the admin user with redhat as the password.
4. Navigate to Virtualization → VirtualMachines. Confirm that the mariadb-server VM is running.

Create the PV resource that declares the iSCSI target to connect.

From the command line on the workstation machine, review the /home/student/DO316/labs/storage-external/pv.yaml resource file that the lab command prepared.

[student@workstation ~]$ cat ~/DO316/labs/storage-external/pv.yaml
apiVersion: v1
kind: PersistentVolume
metadata:
  name: iscsi-pv
spec:
  capacity:
    storage: 1Gi
  accessModes:
    - ReadWriteOnce
  volumeMode: Block
  claimRef:  
    name: mariadb-binlog
    namespace: storage-external
  iscsi:  
     targetPortal: 192.168.51.40:3260
     iqn: iqn.2021-10.com.example:server.disk1
     lun: 0
     initiatorName: iqn.2021-10.com.example:client-server.disk1

	The `claimRef` section specifies that the PV is for a PVC named `mariadb-binlog` in the `storage-external` namespace. A following step instructs you to create that PVC.
	The `iscsi` section provides the details of the iSCSI target in the classroom environment.

Use the oc command to create the resource:
```
[student@workstation ~]$ oc apply -f ~/DO316/labs/storage-external/pv.yaml
persistentvolume/iscsi-pv created
```
If you prefer the OpenShift web console, then navigate to Storage → PersistentVolumes. Click Create PersistentVolume and then copy and paste the ~/DO316/labs/storage-external/pv.yaml resource file into the YAML editor. Click Create.

Run the oc get pv command to verify your work.

[student@workstation ~]$ oc get pv
NAME        CAPACITY    ACCESS MODES    RECLAIM POLICY    STATUS    ...
iscsi-pv    1Gi         RWO             Retain            Available ...
...output omitted...

Create the mariadb-binlog PVC and confirm that Kubernetes binds it to the PV.
1. From the command line, review the /home/student/DO316/labs/storage-external/pvc.yaml resource file that the lab command prepared.
```
[student@workstation ~]$ cat ~/DO316/labs/storage-external/pvc.yaml
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mariadb-binlog
  namespace: storage-external
spec:
  resources:
    requests:
      storage: 1Gi
  accessModes:
    - ReadWriteOnce
  volumeMode: Block
```
  Notice that the name, namespace, storage, accessModes, and volumeMode parameters match the parameters of the PV resource.
2. Use the oc command to create the resource:
```
[student@workstation ~]$ oc apply -f ~/DO316/labs/storage-external/pvc.yaml
persistentvolumeclaim/mariadb-binlog created
```
  If you prefer the OpenShift web console, then navigate to Storage → PersistentVolumeClaims and select the storage-external project. Click Create PersistentVolumeClaim → With Form and then complete the form by using the following information:
  Field Value
  StorageClass Keep the default provided class
  PersistentVolumeClaim name mariadb-binlog
  Access mode Single user (RWO)
  Size 1 GiB
  Volume mode Block
  Click Create.
3. Run the oc get pvc command to confirm that Kubernetes binds your PVC to the iscsi-pv PV.
```
[student@workstation ~]$ oc get pvc -n storage-external
NAME            STATUS  VOLUME    CAPACITY  ACCESS MODES  STORAGECLASS  AGE
mariadb-binlog  Bound   iscsi-pv  1Gi       RWO           nfs-storage   10m
...output omitted...
```
  The command must report the status as Bound and the volume as iscsi-pv.
  Note
  If you do not get that status, then delete the PVC and the PV and start again. Ensure that you create the PVC in the storage-external project with the correct name and parameters.
  Use the oc command to delete the resources:
```
[student@workstation ~]$ oc delete pvc mariadb-binlog -n storage-external
persistentvolumeclaim "mariadb-binlog" deleted
[student@workstation ~]$ oc delete pv iscsi-pv
persistentvolume "iscsi-pv" deleted
```
Attach the mariadb-binlog PVC as a disk to the mariadb-server VM by using a virtio interface.
1. Use the OpenShift web console to stop the VM so that you can use the virtio interface to attach the new disk. Remember that the only available interface is scsi when the VM is running.
  Navigate to Virtualization → VirtualMachines, select the mariadb-server VM, and then click Actions → Stop. Wait for the machine to stop.
2. Navigate to the Configuration tab and then click Add disk. Complete the form by using the following information:
  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.
  Click Save to create and attach the disk to the VM.
  Field Value
  Name binlogdisk
  Source Use an existing PVC
  PVC name mariadb-binlog
  Type Disk
  Interface VirtIO
3. Click Actions → Start and then wait for the machine to start.
4. Log in to the VM console and confirm that a new 1 GiB device is 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 1 GiB vdc block device.
```
[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    1G  0 disk
```
5. Log out of the VM console.
```
[root@mariadb-server ~]# logout
```

Field	Value
StorageClass	Keep the default provided class
PersistentVolumeClaim name	`mariadb-binlog`
Access mode	`Single user (RWO)`
Size	1 GiB
Volume mode	`Block`

Field	Value
Name	`binlogdisk`
Source	`Use an existing PVC`
PVC name	`mariadb-binlog`
Type	`Disk`
Interface	`VirtIO`

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-external

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Welcome to the Managing Virtual Machines with Red Hat OpenShift (DO316) course in RHLC!

Syed

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

Managing Virtual Machines with Red Hat OpenShift Virtualization

Guided Exercise: Connect Virtual Machines to External Storage

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