> ## Documentation Index
> Fetch the complete documentation index at: https://docs.vast.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Instance Types

> Understand Vast.ai instance types - On-demand, Reserved, and Interruptible. Learn how each type works, their differences, and when to use each.

Vast.ai offers three instance types with different priority levels and pricing models to match your workload requirements and budget.

## Overview

<CardGroup cols={3}>
  <Card title="On-demand" icon="shield-check">
    **High Priority**
    Fixed pricing, guaranteed resources
  </Card>

  <Card title="Reserved" icon="piggy-bank">
    **High Priority**
    Discounted rates with pre-payment
  </Card>

  <Card title="Interruptible" icon="shuffle">
    **Low Priority**
    Lowest cost, may be paused
  </Card>
</CardGroup>

In the create interface, you'll see a selector for "on-demand" or "interruptible". Once an instance is rented, you cannot change its type. However, you can convert on-demand instances to reserved for discounts.

## On-demand Instances

**Best for**: Production workloads, continuous training, time-sensitive tasks

On-demand instances provide:

* **Exclusive GPU control** with high priority
* **Guaranteed resources** for the rental period
* **Fixed pricing** set by the host
* **Maximum duration** shown on offer cards
* **Data persistence** even when stopped

### Key Considerations

* Check the maximum duration before renting (shown on offer cards)
* For long-running jobs (days/weeks), verify host reliability scores
* When the rental contract ends, hosts may extend the rental or stop the instance
* Data remains accessible when instances are stopped

<Warning>
  **Expired Instance Deletion**: Expired instances may be deleted 48 hours after expiration. Retrieve your data before then. Expired instances cannot restart while expired.
</Warning>

## Reserved Instances

**Best for**: Long-term projects, predictable workloads, cost optimization

Reserved instances are on-demand instances with pre-paid discounts:

* **Up to 50% discount** based on commitment length
* **Same high priority** as on-demand
* **Convert anytime** from existing on-demand instances
* **Credits locked** to the specific instance
* **Partial refunds** available if cancelled early

To create a reserved instance, first rent on-demand, then convert using the discount badge on your instance card.

<Info>
  For detailed instructions on creating and managing reserved instances, see [Reserved Instances](/guides/instances/choosing/reserved-instances).
</Info>

## Interruptible Instances

**Best for**: Batch processing, fault-tolerant workloads, development/testing

Interruptible instances use a bidding system:

* **Lowest cost** (often 50%+ cheaper than on-demand)
* **Bidding priority** - higher bids get priority
* **May be paused** if outbid or if on-demand requested
* **Data preserved** when paused but instance not functional
* **Resume automatically** when priority returns

### Working with Interruptible Instances

<Warning>
  When using interruptible instances:

  * **Save work frequently** to disk
  * **Use cloud storage** for important outputs
  * **Implement checkpointing** in your code
  * **Expect interruptions** and plan accordingly
</Warning>

Priority rules:

1. On-demand instances always have highest priority
2. Among interruptible instances, highest bid wins
3. Paused instances resume when they regain priority

## Choosing the Right Type

| Use Case              | Recommended Type | Why                                    |
| --------------------- | ---------------- | -------------------------------------- |
| Production inference  | On-demand        | Need guaranteed availability           |
| Multi-day training    | Reserved         | Long-term discount with reliability    |
| Hyperparameter search | Interruptible    | Can handle interruptions, cost matters |
| Data preprocessing    | Interruptible    | Can resume where left off              |
| Time-critical jobs    | On-demand        | Cannot afford interruptions            |
| Development/testing   | Interruptible    | Short sessions, cost-sensitive         |
| Steady workloads      | Reserved         | Predictable usage, want discounts      |

## Quick Reference

### Switching Between Types

* **On-demand → Reserved**: ✅ Yes, anytime via discount badge
* **On-demand → Interruptible**: ❌ No, must create new instance
* **Interruptible → On-demand**: ❌ No, must create new instance
* **Reserved → On-demand**: ⚠️ Lose remaining discount

### Priority Levels

1. **On-demand/Reserved**: High priority, never interrupted
2. **Interruptible (high bid)**: Runs when resources available
3. **Interruptible (low bid)**: Paused until higher bids complete

## Next Steps

* **Compare costs**: Check current [Pricing](/guides/instances/pricing)
* **Get discounts**: Learn about [Reserved Instances](/guides/instances/choosing/reserved-instances)
* **Start renting**: [Finding & Renting](/guides/instances/choosing/find-and-rent)