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Cloning and Attaching a vDisk

A vDisk can be cloned from local and DR snapshots, and attached to an application instance in the same virtual datacenter and storage pool as the snapshot. A vDisk can be cloned and attached as many times as desired. Each clone disk is then independent of other clone disks and of the original snapshot. That is, when you make a change to a clone disk, other clone disks and the original snapshot remain unchanged.

How to clone and attach a vDisk

Attaching a vDisk to an instance from its own snapshot

Method 1:

  1. Select Add vDisk from the Actions drop-down menu or click Add vDisk in the Storage section of the instance's Profile page. add_vdisk_options.PNG
  2. Click Add vDisk clone. add_vdisk_clone_1.PNG
  3. Select the snapshot and vDisk you wish to clone and attach to this instance. add_vdisk_clone_select_vdisk.PNG
  4. Click Clone and Attach to Instance.

Method 2:

  1. On the instance's Local Snapshots page, click ... beside the snapshot and click View vDisks. view_vdisk.PNG
  2. Click ... beside the vDisk you wish to clone and select Clone and attach to this instance.
  3. Click Clone and Attach to this Instance. clone_and_attach_to_this_instance.PNG

Attaching a vDisk to an instance from another instance's snapshot

  1. On the instance's Local Snapshots or Disaster Recovery page, click ... beside the snapshot and click View vDisks. view_vdisk.PNG
  2. Click ... beside the vDisk you wish to clone and select Clone and attach to.
  3. Select the instance you wish to attach the vDisk to, and click Clone and Attach to Instance. clone_and_attach_to.PNG

After adding the disk in Windows

  1. In the instance's console, open Disk Management
  2. Right-click on the newly added disk and select Online. disk_management_clone_disk_right_click.PNG

After adding the disk in Linux

In this example, the new, clone disk is /dev/sdb with partition /dev/sdb1, which has an ext4 filesystem.

  1. In the instance's console, run lsblk to verify the new, clone disk shows up.
  2. Create a mount point: mkdir /disk1
  3. Mount the clone disk to the mount point: mount /dev/sdb1 /disk1
  4. Edit fstab so the new drive automatically mounts to /disk1 on reboot:
    • vi /etc/fstab
    • Enter ESC and type i to edit the file.
    • Add a line: /dev/sdb1 /disk1 ext4 defaults 1 2
    • Enter :wq to write the changes and save the file.

Deleting the clone disk

Note: This action deletes the clone vDisk and leaves the original snapshot intact. If changes were made on the clone disk, they will be lost when this disk is deleted.

  1. On the instance's Profile page, click ... beside the clone vDisk and select Delete disk. clone_disk_options.PNG
  2. Click Delete vDisk. delete_vdisk_clone.PNG

Why cloning and attaching a vDisk is useful

In IT, there are countless situations in which it is desirable to create copies of your production data: to perform tasks such as malware analysis, application development and testing (dev/test), user acceptance testing (UAT), analytics, data protection, archiving and provisioning of new instances. It is not uncommon to see 7-10 copies of production data in enterprises today. Unfortunately, traditional copies don't come for free. They consume significant storage, server and network resources, and valuable administrator time and energy. As a result, many IT shops make do with fewer, and less up-to-date copies than they really need. The problem is so significant that entire companies have been created to attack this problem of copy data management.

Cloudistics' Clone and Attach vDisk feature allows IT administrators to support many data protection and availability use cases directly within the Cloudistics platform, all from only one golden copy of your production data. The application-consistent clones can be created in seconds, are space efficient and available for quick access while also being deduplicated and compressed for backup or long-term retention. Clones allow you to access a single, point-in-time copy of your primary data. The basic operation is Clone and Attach which allows a consistent copy to be made and immediately attached to a new application instance that needs that copy. Clones may also be deleted once their need is over.

The Clone operation

  • Runs Fast - Unlike today's large, multi-TB drive copies which can take many minutes or hours to complete, Cloudistics' Clone and Attach technology allows even the largest disks to be cloned in a matter of seconds.
  • Reduces Costs - A clone uses a small amount of space for metadata, and then only consumes additional space as data is changed or added. As a result, Cloudistics' Clone and Attach feature can cut the storage you need for dev/test or virtual environments by 50% or more.
  • Supports Business Continuity - Cloudistics' Clone and Attach makes it possible to clone and fully test your DR processes, or use your DR environment for dev/test without interfering with ongoing replication. You simply clone your DR copies and do dev/test on the clones.
  • Improves quality of dev/test - Make as many copies of your full production data as you need. If there are 20 users, give each user their own clone if you wish. If a test corrupts the data, start again in seconds. Developers and test engineers spend less time waiting for access to datasets and more time doing productive work.
  • Accelerates server and virtual desktop provisioning - Deploy tens or hundreds of new instances in minutes with only a small incremental increase in storage directly from our application templates.

One customer use case for clones is malware analysis in a VDI environment. By using the Cloudistics API, active instances' disks can be cloned and attached to an instance with malware software installed that does scanning for vulnerabilities. The clone can then be deleted. This is accomplished during normal business operations and without disrupting the production instance.

 

How cloning and attaching a vDisk works

Clone disks have all the capabilities of any other disk, including the ability to be resized, be deduplicated and compressed, be the source of a snapshot, or be cloned. The technology that makes this all possible is integral to how Cloudistics manages storage.

  • Snapshots simply make a copy of the metadata associated with a disk. As data is changed in the base disk, the original blocks stay associated with the snapshot rather than getting marked for reuse. All metadata updates that occur are just pointer changes, so they are very fast. The snapshots are immutable; a clone is simply a snapshot that is writable.
  • You can think of a clone disk as a transparent, writable layer in front of a snapshot. Because a clone disk is writable, it needs disk space to store data that is written to the clone. A snapshot simply links to existing data that was overwritten in the base disk; a clone stores the data written to it on disk and then links to the new data as well. The disk space associated with the snapshot and the clone is accounted for separately from the data in the base disk. 

clone_disk.png

  • When a clone disk is created, it requires an application-consistent snapshot of the disk to use as a base. The clone disk gets a copy of the snapshot metadata and then updates its metadata as the cloned disk is created. Creating the clone takes just a few seconds because the copied metadata is very small compared to the actual data. All changes to the cloned disk are copy-on-write operations and contain only the changed blocks.
  • The original active disk can change independently of the clone disk because the clone is based on the contents of its base snapshot. Since snapshots are read-only, they can be reused as the base for multiple clone disks. Space is used very efficiently because the only new disk space used is associated either with the small amounts of metadata and/or unique writes to the clone disk.

 

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