Linux Patches & Upgrades
This section aims to help you achieve no downtime for your NCache deployment when applying Linux patches.
How to Apply Linux Patches on NCache Server
Note
Please remember that you should always do a maintenance, patching, or upgrading activity, such as applying Linux patches, one node at a time.
The required steps are:
1. Stop Cache
Stop the cache if this node is a part of multiple cache clusters. You need to stop this node from all the cache clusters. This will start the state transfer process and data will be re-adjusted on the other nodes available in the cluster.
You can do this by navigating to the directory ncache_user\opt\ncache\bin\tools and running the following command:
./stop-cache democache
Note
If all caches on a particular node aren’t stopped for applying NCache or Linux patches, this could impact the availability of the cluster.
2. Stop NCache Service
Stop NCache Service on this server. You can do this by navigating to the directory ncache_user\opt\ncache\bin\tools and running the following command, which changes the service start-up type of the NCache Service to disabled using the following command:
sudo systemctl disable ncached.service
After which you will actually stop the NCache Service as follows:
sudo systemctl stop ncached.service
3. Apply Patch
Apply the required Linux patches/updates. Complete all the maintenance tasks running on this machine and then reboot the servers.
4. Restart NCache Service
After successful completion of step 3, now change the service start-up type of the NCache Service to enabled using the command below.
sudo systemctl enable ncached.service
Then restart the NCache Service using the following command:
sudo systemctl start ncached.service
5. Start Cache
Now start the cache manually if auto-start is not enabled.
./start-cache democache
Refresh the cache cluster from NCache Management Centre to view this node as active node in the cluster. Furthermore, you can see the data being transferred to this lately added cache node by monitoring the cache through the NCache performance counters.
Note
You can skip this step if auto-start is already enabled.
Perform the same steps for other nodes in your environment. It is a good practice to start the NCache Service manually once all the patches are fully applied and the maintenance work has been completed on your server.
