AWS Storage Gateway: Hybrid Cloud Storage Bridge
TL;DR
AWS Storage Gateway is the bridge between on-premises and AWS cloud storage. It comes in three types: File Gateway (NFS/SMB to S3), Volume Gateway (iSCSI block storage), and Tape Gateway (virtual tape library). It’s the on-ramp for hybrid cloud — cache hot data locally, archive to S3/Glacier. The catch: requires hardware appliance or VM, adds latency for local access, and isn’t cheap when you factor in data transfer.
What Is It?
Storage Gateway is a hybrid cloud storage service that gives you on-premises access to virtually unlimited cloud storage.
Gateway Types
┌─────────────────────────────────────────────────────────────┐
│ On-Premises Data Center │
│ │
│ ┌──────────────┐ ┌──────────────┐ ┌──────────────┐ │
│ │ File Gateway │ │Volume Gateway│ │ Tape Gateway │ │
│ │ (NFS/SMB) │ │ (iSCSI) │ │ (VTL/VTL) │ │
│ └──────┬───────┘ └──────┬───────┘ └──────┬───────┘ │
│ │ │ │ │
│ └─────────────────┼──────────────────┘ │
│ │ │
│ ┌───────┴───────┐ │
│ │ Local Cache │ │
│ │ (SSD/HDD) │ │
│ └───────┬───────┘ │
└────────────────────────────┼────────────────────────────────┘
│
AWS Direct Connect / VPN
│
┌────────────────────────────▼────────────────────────────────┐
│ AWS Cloud │
│ ┌──────────────┐ ┌──────────────┐ ┌──────────────┐ │
│ │ S3 │ │ S3 + EBS │ │ S3 Glacier │ │
│ │ │ │ Snapshots │ │ (Archive) │ │
│ └──────────────┘ └──────────────┘ └──────────────┘ │
└─────────────────────────────────────────────────────────────┘
1. File Gateway
- Protocol: NFS v3/v4.1, SMB v2/v3
- Backend: S3
- Use case: File shares, content repos, home directories
Features:
- Local cache for low-latency access
- Async upload to S3
- S3 storage classes support
2. Volume Gateway
- Protocol: iSCSI
- Backend: S3 (with EBS snapshots)
- Use case: Block storage, backups, DR
Modes:
- Cached: Primary data in S3, cache hot data locally
- Stored: Primary data local, async backup to S3
3. Tape Gateway
- Protocol: iSCSI VTL
- Backend: S3 + Glacier/Deep Archive
- Use case: Replace physical tape libraries
Pricing
Gateway Pricing
| Component | Price |
|---|---|
| Gateway appliance | Free (VM) or hardware cost |
| Storage | Standard S3/EBS/Glacier rates |
| Data transfer | $0.09/GB out (inbound free) |
Example: File Gateway (10 TB)
| Component | Monthly Cost |
|---|---|
| S3 Standard (10 TB) | $230 |
| Data transfer (1 TB out) | $90 |
| Total | $320 |
GCP Alternative: Cloud Storage for Firebase / Transfer Appliance
GCP doesn’t have a direct Storage Gateway equivalent.
Alternatives:
- Transfer Appliance: Ship physical drives to GCP
- Cloud Storage FUSE: Mount GCS as filesystem
- Third-party: Avere vFXT (Azure now)
Azure Alternative: Azure File Sync + StorSimple
| Feature | AWS Storage Gateway | Azure File Sync |
|---|---|---|
| File caching | Yes | Yes |
| Multi-site sync | No | Yes |
| Cloud tiering | Yes | Yes |
| Tape replacement | Yes | No |
Real-World Use Cases
Use Case 1: Backup Target
Challenge: Replace aging tape library
Solution:
Backup Software → Tape Gateway (VTL)
↓
S3 → Glacier Deep Archive
↓
7-year retention
Use Case 2: Hybrid File Shares
Challenge: 50 offices need shared storage
Architecture:
Each Office → File Gateway
↓
Central S3 bucket
↓
Cross-region replication
Use Case 3: DR for On-Prem VMs
Challenge: Disaster recovery without second DC
Solution:
On-Prem VMware → Volume Gateway (Stored mode)
↓
EBS Snapshots in AWS
↓
DR: Restore to EC2
The Catch
1. Latency
Local cache helps, but writes go to cloud:
- File Gateway: Async upload lag
- Volume Gateway: Snapshot-based recovery
2. Cost Creep
- Data transfer: $0.09/GB adds up
- API costs for high I/O
- Hardware for physical appliance
3. Complexity
- VM management
- Network configuration
- Cache sizing
4. Limited Performance
Max throughput per gateway:
- File: 10 Gbps
- Volume: 2 Gbps
Need multiple gateways for scale.
Verdict
Grade: B
Best for:
- Hybrid cloud transitions
- Tape replacement
- Backup/DR targets
- Distributed offices
When to use:
- Need local cache + cloud archive
- Replacing legacy tape
- Lift-and-shift to hybrid
When to avoid:
- Pure cloud (use native services)
- High-performance local storage
- Cost-sensitive workloads
Researcher 🔬 — Staff Software Architect