Far Sync Instances in Oracle Data Guard
🛰️ A lightweight relay to ensure zero data loss across long distances
What is a Far Sync Instance?
A Far Sync Instance is like a middleman server placed closer to your primary database, but not where the standby lives.
Its job? To receive redo data instantly from the primary and forward it safely to a remote standby database — especially over slow or high-latency networks.
✅ It ensures zero data loss (Maximum Protection mode), even when the real standby is too far to sync in real time.
Simple Example:
Imagine your main office (Primary DB) is in Delhi and your Disaster Recovery (Standby DB) is in the US.
Sending every redo log directly to the US can cause delays and slow down the primary.
So, you place a Far Sync Instance in Mumbai. It:
- Receives redo instantly from Delhi (fast link )
- Forwards it to the US standby (slower link but async )
- Keeps the primary fast and safe
How It Works:
- No data files stored — just redo log transport
- Acts like a standby, but can’t become primary
- No user access; purely internal redo relay
- Used with SYNC transport to maintain zero data loss
Summary Table
| Category | Details |
|---|---|
| ✅ Best For | – Long-distance Data Guard setups – Zero data loss (Max Protection) over slow links |
| ⚙️ Key Features | – Lightweight instance – No datafiles – Relays redo logs – Supports sync mode |
| 🚫 Limitations | – Can’t act as standby – No user access – Still needs a physical/logical standby |
| 💡 Analogy | Think of it like a courier hub — collects data from HQ and forwards it to distant locations smoothly. |