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--- title: Resize persistent volume claim (PVC) for Azure Arc-enabled data services volume description: Explains how to resize a persistent volume claim for a volume used for Azure Arc-enabled data services. services: azure-arc ms.service: azure-arc ms.subservice: azure-arc-sql-mi author: AbdullahMSFT ms.author: amamun ms.reviewer: mikeray ms.date: 07/19/2023 ms.topic: how-to # Customer intent: As a Kubernetes administrator managing Azure Arc-enabled SQL instances, I want to resize persistent volume claims, so that I can accommodate increased storage needs for data, logs, and backups without downtime. --- # Resize persistent volume to increase size This article explains how to resize an existing persistent volume to increase its size by editing the `PersistentVolumeClaim` (PVC) object. > [!NOTE] > Resizing PVCs using this method only works your `StorageClass` supports `AllowVolumeExpansion=True`. When you deploy a SQL Managed Instance enabled by Azure Arc, you can configure the size of the persistent volume (PV) for `data`, `logs`, `datalogs`, and `backups`. The deployment creates these volumes based on the values set by parameters `--volume-size-data`, `--volume-size-logs`, `--volume-size-datalogs`, and `--volume-size-backups`. When these volumes become full, you will need to resize the `PersistentVolumes`. SQL Managed Instance enabled by Azure Arc is deployed as part of a `StatefulSet` for both General Purpose or Business Critical service tiers. Kubernetes supports automatic resizing for persistent volumes but not for volumes attached to `StatefulSet`. Following are the steps to resize persistent volumes attached to `StatefulSet`: 1. Scale the `StatefulSet` replicas to 0 2. Patch the PVC to the new size 3. Scale the `StatefulSet` replicas back to the original size During the patching of `PersistentVolumeClaim`, the status of the persistent volume claim will likely change from: `Attached` to `Resizing` to `FileSystemResizePending` to `Attached`. The exact states will depend on the storage provisioner. > [!NOTE] > Ensure the managed instance is in a healthy state before you proceed. Run `kubectl get sqlmi -n <namespace>` and check the status of the managed instance. ## 1. Scale the `StatefulSet` replicas to 0 There is one `StatefulSet` deployed for each Arc SQL MI. The number of replicas in the `StatefulSet` is equal to the number of replicas in the Arc SQL MI. For General Purpose service tier, this is 1. For Business Critical service tier it could be 1, 2 or 3 depending on how many replicas were specified. Run the below command to get the number of `StatefulSet` replicas if you have a Business Critical instance. ```console kubectl get sts --namespace <namespace> ``` For example, if the namespace is `arc`, run: ```console kubectl get sts --namespace arc ``` Notice the number of stateful sets under the `READY` column for the SQL managed instance(s). Run the below command to scale the `StatefulSet` replicas to 0: ```console kubectl scale statefulsets <statefulset> --namespace <namespace> --replicas= <number> ``` For example: ```console kubectl scale statefulsets sqlmi1 --namespace arc --replicas=0 ``` ## 2. Patch the PVC to the new size Run the below command to get the name of the `PersistentVolumeClaim` which needs to be resized: ```console kubectl get pvc --namespace <namespace> ``` For example: ```console kubectl get pvc --namespace arc ``` Once the stateful `StatefulSet` replicas have completed scaling down to 0, patch the `StatefulSet`. Run the following command: ```console $newsize='{\"spec\":{\"resources\":{\"requests\":{\"storage\":\"<newsize>Gi\"}}}}' kubectl patch pvc <name of PVC> --namespace <namespace> --type merge --patch $newsize ``` For example: the following command will resize the data PVC to 50Gi. ```console $newsize='{\"spec\":{\"resources\":{\"requests\":{\"storage\":\"50Gi\"}}}}' kubectl patch pvc data-a6gt3be7mrtq60eao0gmgxgd-sqlmi1-0 --namespace arcns --type merge --patch $newsize ``` ## 3. Scale the `StatefulSet` replicas to original size Once the resize completes, scale the `StatefulSet` replicas back to its original size by running the below command: ```console kubectl scale statefulsets <statefulset> --namespace <namespace> --replicas= <number> ``` For example: The below command sets the `StatefulSet` replicas to 3. ``` kubectl scale statefulsets sqlmi1 --namespace arc --replicas=3 ``` Ensure the Arc-enabled SQL managed instance is back to ready status by running: ```console kubectl get sqlmi -A ``` ## See also [Sizing Guidance](sizing-guidance.md)