Scaling Disk, RAM, and CPU

You can manually adjust the amount of resources available to your IBM Cloud® Databases for EnterpriseDB deployment to suit your workload and the size of your data.

Resource Breakdown

Databases for EnterpriseDB deployments have three data members in a cluster, and resources are allocated to all members equally. For example, the minimum storage of a Databases for EnterpriseDB deployment is 20480 MB per member, which equates to an initial size of 61440 MB. The minimum RAM for a Databases for EnterpriseDB deployment is 1028 MB per member, which equates to an initial allocation of 3084 MB. The minimum dedicated cores per deployment are 3 per member, for an initial allocation of 9.

Billing is based on the total amount of resources that are allocated to the service.

Disk

Your disk allocation must be enough to store all of your data. Your data is replicated to all data members so the total amount of disk you use is at least twice the size of your data set.

Disk allocation also affects the performance of the disk, with larger disks having higher performance. Baseline Input-Output Operations per second (IOPS) performance for disk is 10 IOPS for each GB. Scale disk to increase the IOPS that your deployment can handle.

You cannot scale down storage.

RAM

If you find that your deployment is suffering from performance issues due to a lack of memory, you can scale the amount of RAM allocated to it. The amount of memory you allocate to your deployment is split between all members. Adding memory to the total allocation adds memory to all members equally.

work_mem, maintenance_work_mem, and effective_cache_size are auto-tuned based on the deployment's total memory. They are also set when you scale memory on your deployment. When you scale, the values are adjusted without outage to the running deployment.

The amount of memory allocated to the database's shared buffer pool is not adjusted automatically when you scale your deployment. It is recommended to be set to 25% of the deployment's total memory. You can manually tune the shared buffer pool through the shared_buffer setting in your Databases for EnterpriseDB's configuration. It is not auto-tuned because changing the shared_buffer requires a database restart.

Dedicated Cores

You can increase the CPU allocation to the deployment. With dedicated cores, your resource group is given a single-tenant host with a reserve of CPU shares. Your deployment is then guaranteed the minimum number of CPUs you specify.

Scaling Considerations

With a minimum of 3 members, allocation minimums begin with 1 Gb RAM, 20 GB Disk, and 3 dedicated cores per member.
Scaling your deployment up might cause your databases to restart. If your scaled deployment needs to be moved to a host with more capacity, then the databases are restarted as part of the move.
Scaling down RAM or CPU does not trigger database restarts.
Disk cannot be scaled down.
A few scaling operations can be more long running than others. Enabling dedicated cores moves your deployment to its own host and can take longer than just adding more cores. Similarly, drastically increasing CPU, RAM, or Disk can take longer than smaller increases to account for provisioning more underlying hardware resources.
Scaling operations are logged in IBM Cloud® Activity Tracker.
If you find consistent trends in resource usage or would like to set up scaling when certain resource thresholds are reached, consider enabling autoscaling on your deployment.

Scaling in the UI

A visual representation of your data members and their resource allocation is available on the Resources tab of your deployment's Manage page.

Figure 1. The Scale Resources Pane in Resources

Adjust the slider to increase or decrease the resources that are allocated to your service. The slider controls how much memory or disk is allocated per member. The UI shows the total allocated memory or disk for the position of the slider. Click Scale to trigger the scaling operations and return to the dashboard overview.

The UI currently uses a coarser-grained resolution for scaling than the CLI or API commands. Use the API or CLI to scale if the stops on the slider do not meet your size requirements.

Scaling in the CLI

IBM Cloud CLI cloud databases plug-in supports viewing and scaling the resources on your deployment. To scale any of the available resource groups, use cdb deployment-groups-set command.

For example, the command to view the resource groups for a deployment named "example-deployment" is,

ibmcloud cdb deployment-groups example-deployment

This produces the output,

Group   member
Count   3
|
+   Memory
|   Allocation              3072mb
|   Allocation per member   1024mb
|   Minimum                 1024mb
|   Step Size               1024mb
|   Adjustable              true
|
+   CPU
|   Allocation              9
|   Allocation per member   3
|   Minimum                 9
|   Step Size               1
|   Adjustable              true
|
+   Disk
|   Allocation              61440mb
|   Allocation per member   20480mb
|   Minimum                 20480mb
|   Step Size               1024mb
|   Adjustable              true

The deployment has three members, with 3072 MB of RAM and 61440 MB of disk allocated in total. The "per member" allocation is 1024 MB of RAM and 20480 MB of disk. The minimum value is the lowest the total allocation can be set. The step size is the smallest amount by which the total allocation can be adjusted.

The cdb deployment-groups-set command allows either the total RAM or total disk allocation to be set, in MB. For example, to scale the memory of the "example-deployment" to 2048 MB of RAM for each memory member (for a total memory of 6144 MB), you use the command

ibmcloud cdb deployment-groups-set example-deployment member --memory 6144

Scaling in the API

The Foundation Endpoint that is shown on the Overview pane of your service provides the base URL to access this deployment through the API. Use it with the /groups endpoint if you need to manage or automate scaling programmatically.

To view the current and scalable resources on a deployment, use

curl -X GET -H "Authorization: Bearer $APIKEY" 'https://api.{region}.databases.cloud.ibm.com/v4/ibm/deployments/{id}/groups'

To scale the memory of a deployment to 2048 MB of RAM for each memory member (for a total memory of 4096 MB).

curl -X PATCH 'https://api.{region}.databases.cloud.ibm.com/v4/ibm/deployments/{id}/groups/member' \
-H "Authorization: Bearer $APIKEY" \
-H "Content-Type: application/json" \
-d '{"memory": {
        "allocation_mb": 4096
      }
    }'

For more information, see API Reference.