Product : Pivot3, Acuity [HCI]/10.6.1, Datacenter
Feature : Disk Failure Protection, Reads/Writes, Data Availability
Content Owner:  Herman Rutten
Erasure Coding (EC1/EC3/EC5)
Global Virtual Sparing
The Pivot3 Acuity platform leverages patented Erasure Coding technology. Pivot3 Acuity Erasure Coding requires at least 3 nodes in a vPG. Pivot3 Acuity Erasure Coding is configured on a per volume basis, so EC levels can be mixed within the same vPG.

Configurable Erasure Coding levels:
EC1: Protects against 1 disk failure event OR 1 node failure event.
EC3: Protects against 3 simultaneous disk failure events OR 1 drive failure event + 1 node failure event.
EC5: Protects against 5 simultaneous disk failure events OR 2 drive failure events + 1 node failure event.

The Pivot3 Acuity platform also leverages a patented Global Virtual Sparing methodology. Whenever a volume is created, it is known what the required capacity for sparing is. Therefore, a small percentage of every drive is reserved for this capacity, meaning that a virtual spare spanning the entirety of the cluster, is created for each volume.

Global Virtual Sparing has two major advantages:
- The overall net capacity is significantly improved, since there is no longer the requirement for a single drive per node to be reserved for sparing. Also, as the system scales, the percentage required for sparing on each
drive decreases and more capacity is made available for application data.
- Since every drive has a small amount of sparing reservation, the performance impact of the failure and the
subsequent data migration or rebuild is distributed across all of the other drives in the vPG. This significantly improves rebuild times and reduces the performance impact on the system during failure conditions.