Worldwide

Thin Provisioning and Space Efficiency

thin provisioning

Allocate just enough space, just-in-time

  • Appears to computers as very large drives (e.g.>2 TB disks)
  • Takes up only space actually being written to
  • Dynamically allocates more disk space when required
  • Reduces need to resize LUNs
  • Reclaims zeroed out disk space
thin provisioning

In these tougher economic and eco-friendly times, thin provisioning gets a lot of press and rightly so. DataCore’s implementation spans any physical devices in the pool, and like its other features, is not dependent on any one host, operating system or hypervisor.

There are two parts to thin provisioning. On the one hand, the storage consumer is assigned very large logical drives. In reality, software only takes up space when it is actually written to. This solves the problem of guessing wrong and wasting space when an application first asks for a lot of capacity even though they may never use it.

Rather than tie up all that space, the software allocates only disk blocks as needed, just-in-time. This works out well with virtual machines that like to mount volumes that are much bigger than they actually need. Some refer to it as oversubscription. You may also reserve a portion of the virtual disk capacity without explicitly allocating it, to ensure that it is set aside for later use.

In the example below, we’ve logically assigned 6 TBs, but the applications have only written to less than ½ TB. When real consumption starts to exhaust the physical space, the software alerts the administrator to add more. You get to set different alarms as space is consumed (information, warning, critical) . Once more drives arrive, you instruct the software to add the new capacity to the existing pool, giving you more room for expansion. The additions take place non-disruptively. Moreover, the additional space could come from completely different equipment given your preferences at the time.

DataCore also includes utilities to reclaim space that was temporarily consumed on thinly provisioned virtual disks and later zeroed out by the host.