Merge pull request #115060 from rachel271/rachel271-containerDocUpdate

Update batch-docker-container-workloads.md

Author: Court72

articles/batch/batch-docker-container-workloads.md

@@ -72,6 +72,31 @@ For Linux container workloads, Batch currently supports the following Linux imag
   - Offer: `centos-container-rdma`
   - Offer: `ubuntu-server-container-rdma`
 
+- Publisher: `microsoft-dsvm`
+  - Offer: `ubuntu-hpc`
+
+#### Notes
+  The docker data root of the above images lies in different places:
+  - For the batch image `microsoft-azure-batch` (Offer: `centos-container-rdma`, etc), the docker data root is mapped to `/mnt/batch/docker`, which is usually located on the temporary disk.
+  - For the HPC image, or `microsoft-dsvm` (Offer: `ubuntu-hpc`, etc), the docker data root is unchanged from the Docker default which is `/var/lib/docker` on Linux and `C:\ProgramData\Docker` on Windows. These folders are usually located on the OS disk.
+
+    When using non-Batch images, the OS disk has the potential risk of being filled up quickly as container images are downloaded.
+#### Potential solutions for customer
+
+Change the docker data root in a start task when creating a pool in BatchExplorer. Here's an example of the Start Task command:
+```csharp
+1)  sudo systemctl stop docker
+2)  sudo vi /lib/systemd/system/docker.service
+    +++
+    FROM:
+    ExecStart=/usr/bin/docker daemon -H fd://
+    TO:
+    ExecStart=/usr/bin/docker daemon -g /new/path/docker -H fd://
+    +++
+3)  sudo systemctl daemon-reload
+4)  sudo systemctl start docker
+```
+
 These images are only supported for use in Azure Batch pools and are geared for Docker container execution. They feature:
 
 - A pre-installed Docker-compatible [Moby container runtime](https://github.com/moby/moby).