Manage Virtual Server Disks

Virtual server storage is provided by disks. A disk is a partition of a data store that is allocated to a specific virtual server. Disks can be assigned as standard or swap disks (there are no swap disks for Windows-based templates). They can also be set as primary (that is, the disk from which an OS will boot).

Managing disks for the entire cloud is handled through the Control Panel's Settings menu. Disks for individual virtual servers are managed through the Control Panel > Cloud > Virtual Servers menu, where you can:

• Add Disks to Virtual Servers
  
• Edit Virtual Server Disks
  
• Migrate Virtual Server Disks
  
• Assign Disk to VS
  
• Delete Virtual Server Disks
  
  

Add Disks to Virtual Servers

On this page:

• Add Disks to Virtual Servers
• Edit Virtual Server Disks
• Migrate Virtual Server Disks
• Assign Disk to VS
• Delete Virtual Server Disks
• Clean Virtual Server Disk

See also:

• Virtual Servers
• Create Virtual Server
• Manage Virtual Server
• Virtual Server Backups
• Virtual Server Backup Schedules

Adding a disk to a virtual server will require that VS should be rebooted. If a VS is running when you try to add a new disk to it, you'll be asked to confirm the reboot.

To add a disk to a virtual server:

1. Go to your Control Panel > Cloud > Virtual Servers menu.
2. Click a VS's label to open its details screen.
3. Click the Storage tab > Disks. 
4. Click the "+" button  or the Create Disk button.
5. Fill in the details:
   
   • Specify disk label.
   • Choose the data store to create a disk on from the drop-down list.

   • Move the slider to the right to specify the desired disk size.

     Please note that support of secondary disks larger than 2 TB is limited. Certain operations might fail. This will be improved in future releases.

      Click here to see the details of adding a disk 2 TB+

     • If you add a disk larger than 2 TB, you will not be able to mount or create a backup of such disk via OnApp Control Panel. These operations may be performed only manually inside a virtual server. Also, resize will not be possible for such disks.
     • You can perform the following operations with a secondary disk that is larger than 2 TB:
       • Migrate 
       • Delete / Wipe 
       • Edit IO limits
       • Rebalance (for VSs with Integrated Storage feature enabled)
     • Make sure to disable the Require format disk option when adding a disk larger than 2 TB.
     • OnApp provides a RAW device available inside a VS that you may use. For example, you may create a GPT partition and format it using any available file system which can be mounted inside VS.

   • Move the Hot Attach slider to the right if you want to enable the hot adding of a disk. In this case, a virtual server is not stopped when the disk is added.

     To run hot attach, a virtual server template should support VirtIO virtualization. The hot attach option is available only on KVM compute resources based on CentOS 6.x/7.x for virtual servers with VirtIO support.

   • Move the Swap Space slider to the right if this disk is swap space.

   • Move the Require Format Disk slider to the right if this disk requires formatting.

   • Move the Mounted slider to the right if the disk should be added to Linux or FreeBSD FSTAB (for Linux/FreeBSD virtual servers).

   • Specify its mount point. The maximum length of a Mount Point is 256 characters. Spaces are not allowed. No more than one slash is allowed. If the mount point is not specified the default mount point will be used:  

     /mnt/onapp-disk-#{disk.identifier}

   • Indicate the file system  - ext3, ext4 or xfs - for Linux based VS.

6. Click the Add Disk button to finish.

Edit Virtual Server Disks

Primary and Swap disks

For primary and swap (Linux, FreeBSD) disks you can only change the label and size.
You can resize the disks when you need. The resize will fail if your current usage is greater than the new size you request. Note that any changes to the disk size will lead to a reboot of your VS.
To change the disk size:

1. Go to your Control Panel > Cloud > Virtual Servers menu.
2. Make sure your virtual server is powered off and click the VS label.
3. Click the Storage tab > Disks.
4. Click the Actions button next to the target disk and then click Edit.
5. You can edit the disk label and size in GB.
6. Click the Save Disk button. 

New disks

For new disks - those which were added after the virtual server was created - you can edit the following:

Migrate Virtual Server Disks

OnApp allows hot and cold migration of virtual server disks:

• Hot migration - the migration of disks between compute resources that share common data stores (or data store zones)
• Cold migration - the migration of disks between compute resources with local storage or across compute zones

You can migrate disks of your virtual servers to other data stores, which are allocated to the same Compute resource. Unlike VS migration, disk cold migration requires the reboot of the VS (despite the template it is based on).

To migrate a disk:

1. Go to your Control Panel > Cloud > Virtual Servers menu.
2. Click the label of your virtual server to open its details screen.
3. Click the Storage tab > Disks.
4. Click the Actions button next to the disk you want to move to another data store, then click the Migrate button.

5. On the screen that appears, select the following options: 

   • Type - select the cold or hot migration type

   • Data store - select the target data store to migrate the disk

6. Click the Start Migrate button. 

Assign Disk to VS

You can temporarily assign a disk to another virtual server that has the same data store in use. The disk will be attached to the target VS, but it is necessary to reboot the target VS and mount the disk manually to make it available. Later you can re-assign the disk back to the primary VS at any appropriate moment.

To assign a disk to another VS:

1. Go to your Control Panel > Cloud > Virtual Servers menu.
2. Click the label of a virtual server to open its details screen.
3. Click the Storage tab > Disks.
4. Click the Actions button next to the disk you want to assign to another VS, then click the Assign to VS button.

5. On the screen that appears, select a target VS from a drop-down box.

6. Click Assign. 

   Be aware, that the source VS will be automatically powered off after assigning a disk to another VS.

To re-assign the disk back to the primary VS:

1. Go to your Control Panel > Cloud > Virtual Servers menu.
2. Click the label of a virtual server to open its details screen.
3. Click the Storage tab > Disks.

4. Click the Actions button next to the disk you want to reassign to source VS, then click the Assign back button. Confirm the action.

   If the target VS is running on XEN compute resource, it will be automatically powered off after re-assigning a disk back to the source VS.

Delete Virtual Server Disks

To delete a disk:

1. Go to your Control Panel > Cloud > Virtual Servers menu.
2. Make sure your virtual server is powered off, then click its label to open its details screen.
3. Click the Storage > Disks tab.
4. Click the Actions button next to the disk you want to delete, then click Delete.
5. In the pop-up window, move the Force Reboot slider to the right, then select the VS shutdown type.

6. Move the Required Startup slider to the right to start up the VS automatically after the network is rebuilt.

   Steps 5 and 6 apply to disks of VSs that are on.

7. Click the Destroy Disk button.

Clean Virtual Server Disks

OnApp Cloud provides two ways to clean VS data when deleting or migrating a VS's disk. By default, OnApp Cloud will format the physical disk space used by a virtual server when that VS's virtual disk is deleted, or when the VS disk is migrated to another data store.

You can also choose to zero out a VS's disk (filling it with zeroes) with the change detailed below which will then take effect for operations queued both via the UI as well as the API.This method will likely have a noticeable impact on deletion times and the load placed on the data store, whilst disks are being filled with zeros as it is a far more IO intensive operation.

To enable this behaviour:

1. Log in via SSH to your Control Panel server.
   
   

2. Open the following configuration file for editing:

   /onapp/interface/config/on_app.yml

3. Set the wipe_out_disk_on_destroy parameter from false to true:

   wipe_out_disk_on_destroy: true

   If this option is not enabled, it may be possible to use data recovery techniques to restore files from a previously deleted disk.

4. Restart the OnApp service:

   service onapp restart

5. Now when deleting disks you would see something along the lines of the following in the logs:

   Running: dd if=/dev/zero of=/dev/onapp-cmd7y65etpxii8/hkct05vbu21fma bs=4M count=256 conv=notrunc oflag=direct