# Running mixed-architecture jobs (X86\_64 and ARM64)
<a name="ecs-managed-instances-multi-architecture"></a>

A single Amazon ECS Managed Instances compute environment and job queue can run both `X86_64` and `ARM64` (AWS Graviton processor-based) jobs. Each job runs on capacity that matches the CPU architecture declared in its job definition. Set the architecture with `runtimePlatform.cpuArchitecture` in the job definition. You do not configure architecture on the compute environment.

To run mixed-architecture jobs, provide a container image that supports both architectures (a multi-architecture image manifest), and register one job definition per architecture that sets `runtimePlatform.cpuArchitecture` to `X86_64` or `ARM64`. You can submit jobs for either job definition to the same job queue.

```
"runtimePlatform": {
  "operatingSystemFamily": "LINUX",
  "cpuArchitecture": "ARM64"
}
```

Then set up the compute environment in one of the following ways:
+ Omit `instanceRequirements` to make all instance types eligible.
+ Specify `allowedInstanceTypes` that cover every architecture your jobs use.

Do not specify instance types  
Omit the `instanceRequirements` field from `managedInstancesProvider.instanceLaunchTemplate` (the setting that restricts which instance types the compute environment can use). All instance types are eligible, and Amazon ECS selects capacity that matches each job's `runtimePlatform.cpuArchitecture`. An `X86_64` job launches on an x86 instance, and an `ARM64` job launches on an AWS Graviton instance from the same compute environment.

Specify instance types that cover the required architectures  
If you set `instanceRequirements.allowedInstanceTypes`, include instance types for every architecture your jobs declare. Amazon ECS infers the architecture from the instance types you allow. The allowed instance types must satisfy each job's `runtimePlatform.cpuArchitecture`. For example, to run both architectures, include:  
+ x86 families, such as `m5` and `c5`
+ AWS Graviton families, such as `m7g` and `c7g`

**Job fails if no matching instance type is available**  
If the allowed instance types do not include any type that matches a job's declared architecture, the job fails with the following reason:  
`ResourceInitializationError: No available instance types were able to satisfy the task and placement constraints.`  
For example, if `allowedInstanceTypes` lists only x86 families and you submit an `ARM64` job, the job fails with this error. To resolve this issue, add an AWS Graviton instance family to `allowedInstanceTypes`. Or, remove `instanceRequirements` to allow all instance types.