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**ENHANCEMENTS**
- Add support for multiple users cluster environments by integrating with Active Directory (AD) domains managed via AWS Directory Service.
- Enable cluster creation in subnets with no internet access.
- Add abbreviated flags for `cluster-name` (-n), `region` (-r), `image-id` (-i) and `cluster-configuration` / `image-configuration` (-c) to the cli.
- Add support for multiple compute resources with same instance type per queue.
- Add support for `UseEc2Hostnames` in the cluster configuration file. When set to `true`, use EC2 default hostnames (e.g. ip-1-2-3-4) for compute nodes.
- Add support for GPU scheduling with Slurm on ARM instances with NVIDIA cards. Install NVIDIA drivers and CUDA library for ARM.
- Add `parallelcluster:compute-resource-name` tag to LaunchTemplates used by compute nodes.
- Add support for `NEW_CHANGED_DELETED` as value of FSx for Lustre `AutoImportPolicy` option.
- Explicitly set cloud-init datasource to be EC2. This save boot time for Ubuntu and CentOS platforms.
- Improve Security Groups created within the cluster to allow inbound connections from custom security groups when `SecurityGroups` parameter is specified for head node and/or queues.
- Build Slurm with `slurmrestd` support.
**CHANGES**
- Upgrade Slurm to version 21.08.5.
- Upgrade NICE DCV to version 2021.3-11591.
- Upgrade NVIDIA driver to version 470.103.01.
- Upgrade CUDA library to version 11.4.4.
- Upgrade NVIDIA Fabric manager to version 470.103.01.
- Upgrade Intel MPI Library to 2021.4.0.441.
- Upgrade PMIx to version 3.2.3.
- Disable package update at instance launch time on Amazon Linux 2.
- Enable possibility to suppress `SlurmQueues` and `ComputeResources` length validators.
- Use compute resource name rather than instance type in compute fleet Launch Template name.
- Disable EC2 ImageBuilder enhanced image metadata when building ParallelCluster custom images.
- Remove dumping of failed compute nodes to `/home/logs/compute`. Compute nodes log files are available in CloudWatch
and in EC2 console logs.
**BUG FIXES**
- Redirect stderr and stdout to CLI log file to prevent unwanted text to pollute the `pcluster` CLI output.
- Fix exporting of cluster logs when there is no prefix specified, previously exported to a `None` prefix.
- Fix rollback not being performed in case of cluster update failure.
- Do not configure GPUs in Slurm when NVIDIA driver is not installed.
- Fix `ecs:ListContainerInstances` permission in `BatchUserRole`.
- Fix `RootVolume` schema for the `HeadNode` by raising an error if unsupported `KmsKeyId` is specified.
- Fix `EfaSecurityGroupValidator`. Previously, it may produce false failures when custom security groups were provided and EFA was enabled.
- Fix FSx metrics not displayed in Cloudwatch Dashboard.