GCP Eon Mode Instance Recommendations
When you use the MC to deploy an Eon Mode database to the Google Cloud Platform (GCP), you choose the instance type to deploy as the database's nodes. The default instance settings in the MC are the more conservative option (currently, n1-standard-16). They are sufficient for most workloads. However, you may choose instances with more memory (such as n1-highmem-16) if your queries perform complex joins that may otherwise spill to disk. You can also choose instances with more cores (such as n1-standard-32), if you perform highly-complex compute-intensive analysis. For details on the configuration of the instance options, see the Google Cloud documentation's Machine types page. For details on the machine types that are available when deploying Vertica to GCP, see Supported GCP Machine Types.
The more powerful instance you choose, the higher the cost per hour. You need to balance whether you want to use fewer, higher-powered but more expensive instances vs. relying on more lower-powered instances that cost less. Thanks to Eon Mode's elasticity, if you choose to use the less-powerful instances, you can always add more nodes to meet peak demands. When you reduce the number of instances to a minimum during off-peak times, you'll spend less than if you had a similar number of more-powerful instances.
The MC's deployment wizard also asks you to select the type of local storage for your instances. You can select different options for each type of local storage that Vertica uses: the catalog, the depot, and temporary space. For all of these storage locations, you choose the type of disks to use (standard vs. SSD). You will see the best performance with SSD disks. However, SSD disks cost more.
For the depot, you also choose whether to use local or persistent disks. The local option is faster, as it resides directly on the virtual machine host. However, whenever you shut down the node, this storage is wiped clean. The persistent storage is slower than the local option, as it is not stored directly on the machine hosting the instance. However, it is not wiped out whenever you shut down the instance. See the Google Cloud documentation's Storage options page for more information.
Which of these options you choose depends on how much depot warming the nodes must perform when starting. If the content of your node's depots change little over time (or you tend to frequently start and stop instances), using persistent storage makes sense. In this case, the depot's warming period will be shorter because most of the data the node needs to participate in queries may still be in its depot when it starts. It will perform fewer fetches of data from communal storage while participating in queries.
If your working data set is rapidly changing or you tend to leave nodes stopped for extended periods of time, your best choice is usually to use local storage. In this scenario, the data in the node's depot when it restarts is usually stale. To participate in queries, the node must fetch much of the data it needs from communal storage, resulting in slower performance until it has warmed its depot. Using local ephemeral storage makes sense here, because you will get the benefit of having faster depot storage. Because your nodes have to warm their depots anyhow, there is less of a downside of having the depot on ephemeral storage.
For general guidelines on scaling your cluster for Eon Mode database, see Configuring Your Vertica Cluster for Eon Mode.