VAST Data Platform Data Recovery
VAST Data's platform uses a disaggregated shared-everything (DASE) architecture, separating stateless compute nodes (CNodes) from storage enclosures (DBoxes) built on storage class memory and QLC flash. Recovery cases typically involve the Element Store metadata layer or the locally decodable erasure coding scheme that protects data across DBoxes, rather than any single drive.
Platform Lineage and Naming
VAST Data introduced its Universal Storage platform built around the DASE architecture, aiming to combine the economics of QLC flash with the performance characteristics usually associated with higher tiers by using storage class memory as a persistent write buffer ahead of QLC capacity flash.
The platform has been extended over successive releases with additional protocol support (adding S3 object access alongside its original NFS/SMB file services) and similarity-based data reduction techniques intended to improve effective capacity across mixed workloads.
- DASE — Disaggregated Shared-Everything, VAST's architectural model
- CNode — stateless compute node handling protocol and data services
- DBox — storage enclosure containing storage class memory and QLC flash
- Element Store — VAST's metadata and data layout engine
Generations and Models We Evaluate
| Generation / family | Models |
|---|---|
| Compute | CNodes — stateless, scale independently of storage capacity |
| Storage enclosures | DBoxes with NVMe storage class memory and QLC flash drives |
| Deployment | On-premises clusters scaling CNodes and DBoxes independently |
Architecture and Data Layout
In VAST's DASE model, every CNode has equal, direct access to every DBox over NVMe fabric, rather than data being partitioned or owned by specific nodes; this shared-everything approach means CNode failures do not require data migration since any surviving CNode can serve any data.
Writes land first in storage class memory (SCM) on the DBoxes, acting as a low-latency write buffer, before being organised and written down to QLC flash in patterns suited to that media's write characteristics. Protection is provided by locally decodable erasure codes spread across many DBoxes, allowing high fault tolerance without the write amplification that would otherwise affect QLC media.
Element Store is VAST's metadata and data-layout engine, tracking both the logical file/object namespace and physical placement across SCM and QLC tiers; similarity-based data reduction operates within this layer to identify and eliminate redundant data patterns across the whole namespace rather than per-file.
Protocols and formats: NFSv3 / NFSv4.1, SMB2/SMB3, S3 object, NVMe over Fabrics (internal DBox connectivity)
- Data protection uses locally decodable erasure codes distributed across many DBoxes, which differs from traditional RAID or simple erasure coding in how efficiently it can tolerate multiple failures without excessive rebuild overhead.
- The storage class memory write buffer and QLC capacity tier are logically distinct layers within Element Store; failures affecting the SCM tier can impact recently written data pending destage to QLC flash.
Failure Scenarios
Logical failures
- Element Store metadata corruption following an interrupted software upgrade
- Accidental deletion of files, objects, or namespaces at the client or protocol layer
- Similarity-based data reduction inconsistency after abnormal cluster shutdown
- Snapshot expiry or removal before a needed restore point
Hardware failures
- Multiple DBox failures exceeding the erasure coding scheme's tolerance
- Storage class memory device failures with unflushed writes pending destage to QLC flash
- NVMe fabric failures disrupting CNode-to-DBox connectivity across the cluster
- Concentrated QLC flash failures within a single DBox or enclosure
Encryption and credentials
VAST supports encryption of data at rest; key management state should be preserved alongside affected DBoxes, since encrypted QLC and SCM content cannot be interpreted without it.
What Not To Do Before an Evaluation
- Do not run rebuilds, reconstructions or re-initialisations against an array that has already lost more drives than its protection level allows.
- Do not recreate pools, aggregates, disk groups, storage pools or clusters — these operations write new metadata over the structures a recovery needs.
- Do not swap drives between slots, and do not reorder shelves. Record the original slot and shelf positions before removing anything.
- Do not run file-system repair tools against production volumes before the underlying storage layer has been evaluated.
- Do not restore a backup or replication set over the affected volumes until the recovery scope has been assessed.
- Do not eradicate deleted volumes or empty recycle/destroyed states on platforms that hold deleted data for a retention window.
Our Evaluation and Recovery Process
- Intake and platform identification — array model, generation, firmware, protection layout and the sequence of events that led to the failure.
- Read-only evaluation of the media and array structures, including assessment of drive health and the extent of any physical damage.
- Forensic imaging of all contributing media, with cleanroom work where drives require it. Originals are preserved unaltered.
- Reconstruction of the storage layer — pools, aggregates, parity groups, chunklets, extent groups or objects — from the images.
- Extraction of the layers above: file systems, virtual machines, databases, mailboxes and shares.
- Verification against a file list and customer-nominated critical data, followed by secure return on encrypted media.
Frequently Asked Questions
Can a single DBox be recovered on its own?
Rarely in isolation. The locally decodable erasure coding scheme spreads protection across many DBoxes, so a recovery evaluation generally needs visibility into a representative portion of the cluster.
Does a CNode failure put data at risk?
Not directly — CNodes are stateless in the DASE model, so any surviving CNode can access data on the DBoxes; CNode failure mainly affects available compute capacity rather than data integrity.
What happens if the storage class memory tier fails?
Recently written data that had not yet been destaged from SCM to QLC flash may be affected; the extent depends on how much unflushed data existed at the time of failure.