Merge pull request #104281 from ronhogue/ronh20200213

hpc-cache: add nas prereqs & note about update

Author: PMEds28

articles/hpc-cache/hpc-cache-manage.md

@@ -69,6 +69,8 @@ The software update can take several hours. Caches configured with higher throug
 
 When a software upgrade is available, you will have a week or so to apply it manually. The end date is listed in the upgrade message. If you don't upgrade during that time, Azure automatically applies the update to your cache. The timing of the automatic upgrade is not configurable. If you are concerned about the cache performance impact, you should upgrade the software yourself before the time period expires.
 
+If your cache is stopped when the end date passes, the cache will automatically upgrade software the next time it is started. (The update might not start immediately, but it will start in the first hour.)
+
 Click the **Upgrade** button to begin the software update. The cache status changes to **Upgrading** until the operation completes.
 
 ## Delete the cache

articles/hpc-cache/hpc-cache-prereqs.md

@@ -4,7 +4,7 @@ description: Prerequisites for using Azure HPC Cache
 author: ekpgh
 ms.service: hpc-cache
 ms.topic: conceptual
-ms.date: 10/30/2019
+ms.date: 02/12/2020
 ms.author: rohogue
 ---
 
@@ -65,12 +65,6 @@ The cache supports Azure Blob containers or NFS hardware storage exports. Add st
 
 Each storage type has specific prerequisites.
 
-### NFS storage requirements
-
-If using on-premises hardware storage, the cache needs to have high-bandwidth network access to the datacenter from its subnet. [ExpressRoute](https://docs.microsoft.com/azure/expressroute/) or similar access is recommended.
-
-NFS back-end storage must be a compatible hardware/software platform. Contact the Azure HPC Cache team for details.
-
 ### Blob storage requirements
 
 If you want to use Azure Blob storage with your cache, you need a compatible storage account and either an empty Blob container or a container that is populated with Azure HPC Cache formatted data as described in [Move data to Azure Blob storage](hpc-cache-ingest.md).
@@ -89,6 +83,52 @@ It's a good practice to use a storage account in the same location as your cache
 
 You also must give the cache application access to your Azure storage account as mentioned in [Permissions](#permissions), above. Follow the procedure in [Add storage targets](hpc-cache-add-storage.md#add-the-access-control-roles-to-your-account) to give the cache the required access roles. If you are not the storage account owner, have the owner do this step.
 
+### NFS storage requirements
+
+If using an NFS storage system (for example, an on-premises hardware NAS system), make sure it meets these requirements. You might need to work with the network administrators or firewall managers for your storage system (or data center) to verify these settings.
+
+> [!NOTE]
+> Storage target creation will fail if the cache has insufficient access to the NFS storage system.
+
+* **Network connectivity:** The Azure HPC Cache needs high-bandwidth network access between the cache subnet and the NFS system's data center. [ExpressRoute](https://docs.microsoft.com/azure/expressroute/) or similar access is recommended. If using a VPN, you might need to configure it to clamp TCP MSS at 1350 to make sure large packets are not blocked.
+
+* **Port access:** The cache needs access to specific TCP/UDP ports on your storage system. Different types of storage have different port requirements.
+
+  To check your storage system's settings, follow this procedure.
+
+  * Issue an `rpcinfo` command to your storage system to check the needed ports. The command below lists the ports and formats the relevant results in a table. (Use your system's IP address in place of the *<storage_IP>* term.)
+
+    You can issue this command from any Linux client that has NFS infrastructure installed. If you use a client inside the cluster subnet, it also can help verify connectivity between the subnet and the storage system.
+
+    ```bash
+    rpcinfo -p <storage_IP> |egrep "100000\s+4\s+tcp|100005\s+3\s+tcp|100003\s+3\s+tcp|100024\s+1\s+tcp|100021\s+4\s+tcp"| awk '{print $4 "/" $3 " " $5}'|column -t
+    ```
+
+  * In addition to the ports returned by the `rpcinfo` command, make sure that these commonly used ports allow inbound and outbound traffic:
+
+    | Protocol | Port  | Service  |
+    |----------|-------|----------|
+    | TCP/UDP  | 111   | rpcbind  |
+    | TCP/UDP  | 2049  | NFS      |
+    | TCP/UDP  | 4045  | nlockmgr |
+    | TCP/UDP  | 4046  | mountd   |
+    | TCP/UDP  | 4047  | status   |
+
+  * Check firewall settings to be sure that they allow traffic on all of these required ports. Be sure to check firewalls used in Azure as well as on-premises firewalls in your data center.
+
+* **Directory access:** Enable the `showmount` command on the storage system. Azure HPC Cache uses this command to check that your storage target configuration points to a valid export, and also to make sure that multiple mounts don't access the same subdirectories (which risks file collisions).
+
+  > [!NOTE]
+  > If your NFS storage system uses NetApp's ONTAP 9.2 operating system, **do not enable `showmount`**. [Contact Microsoft Service and Support](hpc-cache-support-ticket.md) for help.
+
+* **Root access:** The cache connects to the back-end system as user ID 0. Check these settings on your storage system:
+  
+  * Enable `no_root_squash`. This option ensures that the remote root user can access files owned by root.
+
+  * Check export policies to make sure they do not include restrictions on root access from the cache's subnet.
+
+* NFS back-end storage must be a compatible hardware/software platform. Contact the Azure HPC Cache team for details.
+
 ## Next steps
 
 * [Create an Azure HPC Cache instance](hpc-cache-create.md) from the Azure portal