# RetainRuleProperty

*[Custom snapshot and AMI policies only]* Specifies a retention rule for snapshots created by snapshot policies, or for AMIs created by AMI policies.

> For snapshot policies that have an [ArchiveRule](https://docs.aws.amazon.com/dlm/latest/APIReference/API_ArchiveRule.html) , this retention rule applies to standard tier retention. When the retention threshold is met, snapshots are moved from the standard to the archive tier.
>
> For snapshot policies that do not have an *ArchiveRule* , snapshots are permanently deleted when this retention threshold is met.

You can retain snapshots based on either a count or a time interval.

- *Count-based retention*

You must specify *Count* . If you specify an [ArchiveRule](https://docs.aws.amazon.com/dlm/latest/APIReference/API_ArchiveRule.html) for the schedule, then you can specify a retention count of `0` to archive snapshots immediately after creation. If you specify a [FastRestoreRule](https://docs.aws.amazon.com/dlm/latest/APIReference/API_FastRestoreRule.html) , [ShareRule](https://docs.aws.amazon.com/dlm/latest/APIReference/API_ShareRule.html) , or a [CrossRegionCopyRule](https://docs.aws.amazon.com/dlm/latest/APIReference/API_CrossRegionCopyRule.html) , then you must specify a retention count of `1` or more.
- *Age-based retention*

You must specify *Interval* and *IntervalUnit* . If you specify an [ArchiveRule](https://docs.aws.amazon.com/dlm/latest/APIReference/API_ArchiveRule.html) for the schedule, then you can specify a retention interval of `0` days to archive snapshots immediately after creation. If you specify a [FastRestoreRule](https://docs.aws.amazon.com/dlm/latest/APIReference/API_FastRestoreRule.html) , [ShareRule](https://docs.aws.amazon.com/dlm/latest/APIReference/API_ShareRule.html) , or a [CrossRegionCopyRule](https://docs.aws.amazon.com/dlm/latest/APIReference/API_CrossRegionCopyRule.html) , then you must specify a retention interval of `1` day or more.

- Source: Generated code
- Type last changed: v2.93.0 · 23 Aug 2023

## Example

```ts
// The code below shows an example of how to instantiate this type.
// The values are placeholders you should change.
import { aws_dlm as dlm } from 'aws-cdk-lib';
const retainRuleProperty: dlm.CfnLifecyclePolicy.RetainRuleProperty = {
  count: 123,
  interval: 123,
  intervalUnit: 'intervalUnit',
};
```

## Properties

- `count`: number — The number of snapshots to retain for each volume, up to a maximum of 1000.

  For example if you want to retain a maximum of three snapshots, specify `3` . When the fourth snapshot is created, the oldest retained snapshot is deleted, or it is moved to the archive tier if you have specified an [ArchiveRule](https://docs.aws.amazon.com/dlm/latest/APIReference/API_ArchiveRule.html) .

- `interval`: number — The amount of time to retain each snapshot.

  The maximum is 100 years. This is equivalent to 1200 months, 5200 weeks, or 36500 days.

- `intervalUnit`: string — The unit of time for time-based retention.

  For example, to retain snapshots for 3 months, specify `Interval=3` and `IntervalUnit=MONTHS` . Once the snapshot has been retained for 3 months, it is deleted, or it is moved to the archive tier if you have specified an [ArchiveRule](https://docs.aws.amazon.com/dlm/latest/APIReference/API_ArchiveRule.html) .