Data Avoidance

  • 26 June 2021
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Data Avoidance technologies typically contribute the most to data efficiency because they prevent the creation of unnecessary data, which also minimizes the need for more resource-demanding data reduction technologies. With fewer back-end operations, more resources are available for front-end (user-driven) operations and applications. As Nutanix enables its built-in data avoidance technologies automatically, there is no need for manual configuration or fine-tuning.

Thin Provisioning

Thin Provisioning is a simple and broadly adopted technology for increasing data capacity utilization by overcommitting resources. Nutanix enables this feature in all containers by default. 

In deployments using the VMware ESXi hypervisor, containers are presented to hosts as natively thin-provisioned NFS datastores. Although it is a widely accepted method for increasing capacity utilization, thin provisioning traditionally has been associated with reduced storage performance. However, on Nutanix, thin provisioning outperforms thick provisioning and it is recommended for all workloads.

Some applications, such as Oracle RAC and vSphere Fault TOlerance, require thick provisioning. Nutanix storage supports thick provisioning (eager zero or lazy zero thick) VMDKs via the VMware API for Array Integration (VAAI) NAS reserve space primitive. Eager-zeroed thick VMDKs guarantee space reservations but do not actually write data. Instead, the distributed storage fabric acknowledges every I/O operation and performs a simple metadata update.

Calculations for overall efficiency metric account for savings from thin provisioning. Administrators can view the current thick provisioned capacity via Prism on the Storage Container Details page.

Intelligent Cloning:

Nutanix Storage provides native support for space-efficient, offloaded VM clones, which you can choose to provision automatically via VAAI, view Composer for Array Integration (VCAI) and Microsoft Offloaded Data Transfer (ODX), or interactively via nCLI, REST or Prism. Clones take advantage of the redirect-on-write algorithm, which is the most effective and efficient implicit virtual disk sharing technique.

On the Nutanix platform, VMs store data as virtual disk files (vDisks). Each vDisk is composed of logically contiguous chunks of data called Extents. These extents are stored in physically contiguous groups as files on storage devices. When you clone a VM, the system marks the base vDisk read-only and creates another vDisk as read and write. At this point, both vDisks have the same block map, which is a metadata mapping of the vDisk to its corresponding extents.

When you clone a VM, the system uses the same method for multiple clones of a VM or vDisk. Clone operations are metadata only, so no I/O takes place. You can also create clones of clones the same way; essentially, the previously cloned VM acts as the base vDisk. On Cloning, the system locks the base vDisk’s block map and creates two clones, with one block map for the previously cloned VM and another block map for the new clone. There is no maximum number of clones.

For more information, please refer to the Data Effeciency

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