Manage Persistent Storage and VMs

How to manage storage volumes for attaching to VMs and VMs created and running on storage volumes in the hybrid cloud platform.

Manage persistent volumes

In private cloud datacenters, depending on your environment, you can work with virtual storage in the form of volumes and hard disks.

Volumes on external storage devices are persistent and independent of the VMs. In contrast, hard disks on the hypervisor datastore are non-persistent and they are destroyed when deleted from the VMs or when the VMs are undeployed. This section covers volumes.

Display persistent storage

To display external storage volumes, go to Virtual datacenters → Volumes

Creating a Volume of Managed Storage

To create a new volume of integrated storage, select the virtual datacenter, click the  button and complete the form:

After you create the volume, to attach it to a VM, edit the VM and go to the Storage tab. See VM storage

For information about creating generic iSCSI volumes, see Creating a Generic iSCSI Volume

Modifying an Existing Volume

To edit a volume, select the volume and click the edit button. For managed storage volumes, you can modify the Controller type, and on ESXi you can also modify the Controller.

Resizing Integrated Storage Volumes

 You can only increase volume size of managed storage volumes, not generic iSCSI storage volumes. After you change the size, remember to enlarge the partitions and file system.

Integrated storage volumes can be resized but only to increase their size. Abiquo does not allow you to make a volume smaller, so as to prevent data loss. This might be because you need additional space on a hard disk, for example, to add service packs/hotfixes, logs, increased swap disk space or temporary system disk space, or for growing installed applications. To resize a volume, first  power off  the VM the volume is attached to.

After resizing a disk, remember to resize the partitions and filesystems. For example, with the Linux ext3 filesystem, you can execute the following commands when logged into a shell on the VM:

 $ umount /dev/xxx (/dev/xxx is the partition of the resized volume, inside the VM)
 $ parted /dev/xxx
 # resize Y start end (Y is the partition number, and start/end of the partition varies in each case)
 $ resize2fs /dev/sdx

Moving Volumes Between Virtual Datacenters

Both managed storage and generic iSCSI volumes can be moved between virtual datacenters, but only if the volumes are not attached to a VM. Volumes can be moved between virtual datacenters that belong to the same physical datacenter and enterprise.

To change the virtual datacenter of a volume,

1. Go to Virtual datacenters → Storage 
2. Drag the volume into the new virtual datacenter in the V. Datacenters list 
3. Click Confirm on the popup to complete the move.

Deleting a Volume

Notes about deleting volumes:

• You can only delete or remove volumes that are NOT attached to a VM. 
• You cannot delete persistent template volumes if they are used in a virtual appliance. 
• When you delete a an Integrated storage volume, it will be deleted in the disk cabinet and the data on the volume will be destroyed. 
• When you delete a generic iSCSI volume, it will be removed from Abiquo (without deleting it in the disk cabinet).

To delete a volume:

1. Select the volume 
2. Click the trash delete button.

Create a persistent VM template from a standard template

You can create persistent VM templates by saving standard VM templates to volumes. The platform stores the system disks of VMs with persistent VM templates on external storage volumes. The platform does not delete the changes to these disks when you undeploy these VMs.

You can select a template and save it to a volume as a persistent VM. The persistent VM will deploy using the volume and the changes you make to the VM will be saved on the volume.

To create a persistent VM do the following steps:

1. Go to Virtual datacenters → Persistent VM templates
2. Click the + add button
3. Select the master or instance template that you would like to save to the persistent volume.
   
4. Enter a Name to identify the persistent template.
5. Select the Disks to save, and a Tier for creating each volume, and optionally enter the Volume name
   
   
6. If you wish to create more persistent templates, select the Keep dialog open checkbox. 
7. To create the template, click Start

When a persistent template is complete, it will be available to create VMs in the virtual appliance.

To manage the volume, go to Virtual datacenters → Persistent VM templates

Modify Persistent Templates

To modify a persistent template:

1. Go to Virtual datacenters → Persistent VM templates 
2. Select the template and from the options menu select Edit
3. You can edit the template in a similar way as a standard template. See Modify a VM Template.

Move persistent templates between virtual datacenters

To move persistent templates between virtual datacenters:

1. Go to Virtual datacenters → Persistent VM templates
2. Drag a persistent template that is not deployed from the template list to another virtual datacenter in the Virtual datacenters list.

Delete Persistent Templates

You can delete a template that is not used in a virtual appliance. An unused template has empty virtual appliance and VM names in the list. Select the template and click the delete button to remove the template.

If a persistent conversion was not successful, the template will be marked on the Persistent VM templates tab with the FAILED status. If the template has other disks, you may be able to recover the template by removing the failed disk. To remove a failed disk, select the template. Edit the template, go to the Disks tab, select the disk and click the delete button.

Create persistent VMs using persistent templates

Persistent VM templates are available on the Persistent VM tab of the virtual appliance templates panel. You can create a single VM from the persistent VM template and deploy it in the usual way. A VM with a persistent system disk has a disk symbol on the VM icon. When you undeploy the persistent VM, the volume will remain intact and the persistent VM will return to the Persistent VM tab.

When you deploy a persistent VM, the persistent template moves to the virtual appliance and is no longer available in the virtual datacenter.

To access information about the persistent VM's external disks, click on the Storage panel.

Deploy a Persistent VM

Deploy the persistent VM or the whole virtual appliance by clicking one of the green Deploy buttons as usual. 

Sharing Persistent VMs

Persistent VM templates can only be used in ONE VM at a time, to avoid concurrent modifications to the VM.

Because persistent VM templates cannot be shared, they do not appear in the Appliance Library View. To share a persistent VM template, deploy a persistent VM and create an instance, which will be available for deployment in other VMs.

Reusing Persistent Templates

When you delete a persistent VM from the virtual appliance, the template remains on the volume on the storage device.

This means that the persistent VM template will appear again on the Persistent VM page for the user to create another VM.

You can move a persistent VM to another virtual datacenter by dragging and dropping it there on the Virtual datacenters → Persistent VM templates tab.

Deleting Persistent VMs

When you click the delete button to remove a persistent VM from your virtual appliance, the persistent template will not be deleted from the storage volume. It will be available in your virtual datacenter for reuse in another virtual appliance.

To delete the persistent VM template:

1. Go to Virtual datacenters → Persistent VM Templates
2. Select the template and click the trash delete button

Persistent volumes

What happens when I create a volume and attach it to a VM?

Persistent VM templates

There are two provisioning approaches supported by the Abiquo platform: non-persistent and persistent. This is a simple example with only one persistent disk.

The Non-persistent Approach: Abiquo provisions the VM and copies a standard disk to the cloud node or creates a new hard disk on the datastore. When the user undeploys the VM, the data on the standard disk will be overwritten. This is the default process in the Abiquo platform.

The Persistent Approach: Abiquo provisions the VM and the persistent disk is located on external storage. When the user undeploys the virtual appliance, the VM data is kept on the volume of external storage.

Persistent Template Volumes on ESXi

Abiquo avoids performing a full HBA rescan of storage on ESX or ESXi for performance reasons. Instead it checks for a raw device mapping for a given IQN and LUN. However, if a volume has been removed or replaced in the storage device, Abiquo may try to attach a volume that does not exist or is completely different to one previously configured, causing an error. This situation may occur with: managed storage volumes, generic iSCSI volumes and persistent VMs. It can be resolved by manually performing a full HBA rescan of all ESX or ESXi hosts that had raw device mappings for the devices involved.

What Happens When I Click Make Persistent?

The following diagram shows a simplified example of the persistent template process for a single persistent system disk.

Related pages

• Work with VMs
  • Manage Virtual Machines
  • Configure Virtual Machines
    • VM storage
• Administer virtual resources
  • Manage Virtual Datacenters
  • Manage Networks
  • Manage Firewalls
  • Manage Load Balancers
  • Administer and Troubleshoot VMs
• Configure datacenter storage, see Storage