The below architecture diagrams shows how all the underlying AWS resources and services are connected to create a single Everpure Cloud Dedicated (PSC Dedicated) instance. PSC Dedicated's architecture is designed to take the best properties of each of the resources and provide an abstraction layer that gives customers the best possible storage experience without the compromising on data services, performance, availability, or durability.
Controllers
The Purity Operating Environment (POE) runs on the PSC Dedicated controllers, which consist of two AWS EC2 instances. The dual controllers ensure high data accessibility and availability in the event of a single controller (EC2) failure. iSCSI connections can receive and transmit IO traffic through both controllers. The PSC Dedicated controllers process the data (deduplicate, compress, and encrypt) before writing to the underlying storage resources.
NVRAM
PSC Dedicated uses high-performance io2 volumes as the NVRAM modules. All host write IOs are initially cached to the io2 volumes. A write IO is immediately acknowledged back to the application host after it has been securely written and mirrored onto two io2 volumes.
Virtual Drives
The flash modules of a PSC Dedicated instance are called Virtual Drives (VDrives). Each VDrive is composed of an EC2 instance and a direct attached high-speed NVMe instance store volume. Once a host IO is mirrored to two NVRAM modules, data is eventually flushed to the instance store volumes with the VDrives. Since Instance Store provide high speed NVMe data access, it is ideal to service all host read IOs.
Virtual Shelf
A Virtual Shelf is a grouping of seven individual Virtual Drives. Data is written across the Virtual Shelf using RAID-HA to protect against concurrent dual Virtual Drive failures within a Virtual Shelf.
Amazon S3
In order to ensure the highest durability, all data residing on the Virtual Drives are copied and persisted into Amazon S3. Any Virtual Drive failures will result in a data restore from Amazon S3.
DynamoDB
DynamoDB is used to store metadata and configuration information about a PSC Dedicated instance. Customer data is not stored on DynamoDB.
AWS Key Management Service
Everpure Cloud Dedicated (PSC Dedicated) performs in-line encryption prior to persisting data to the backend storage. To perform the encryption, it uses an internal data encryption key that is generated when the PSC Dedicated instance is initially deployed. To increase security, the data encryption key itself is also encrypted using a customer managed key (CMK) generated and managed by AWS Key Management Service (KMS). Interaction between the PSC Dedicated instance and KMS only occurs during the initial deployment of a PSC Dedicated instance or when a PSC Dedicated controllers boots up. KMS is never in the data path.
PSC Dedicated on AWS Architecture - Base Deployment
After Capacity NDU