Auto Scaling
Auto Scaling adjusts a cluster's number of nodes as its workload changes. Use it for workloads with unpredictable demand when you want VeloDB Cloud to manage capacity within limits that you set.
The node size and cache capacity per node stay the same. Total compute and cache capacity change with the number of nodes.
Warning:
- Scaling can temporarily interrupt connections and delay requests.
- Reducing the number of nodes reduces total cache capacity and can affect query response times.
- The cluster can scale out to the configured maximum number of nodes, increasing charges.
Before you begin
- You need permission to manage compute resources in the warehouse.
- The cluster must be Running, and the warehouse must not be in the Creating state.
- If Scaling is unavailable, point to it to view the reason.
- Review the current node size and cache per node before choosing the node count range.
Enable Auto Scaling
Choose Minimum number of nodes to support the cluster's baseline workload. Choose Maximum number of nodes based on expected peak demand and your budget.
- Log in to the VeloDB Cloud console.
- In the upper-left corner, select the warehouse that contains the cluster.
- In the left navigation pane, under Compute, click Clusters.
- Click Physical Clusters.
- Click Card, then select the running cluster to display its details panel.
- Click Scaling.
- If a resource menu opens, select On-Demand (Hourly).
- In Scaling Mode, select Auto Scaling.
- Review Node Size, Cache per Node, and Number of Nodes under Current Configuration.
- Under Target Configuration Range, set Minimum number of nodes and Maximum number of nodes.
- Click Enable.
To verify the configuration, reopen Scaling Mode, select Auto Scaling, and check the saved node count range.
Change the node count range
- Open Scaling Mode for the cluster and select Auto Scaling.
- If Auto Scaling is enabled, click Disable.
- Change Minimum number of nodes or Maximum number of nodes.
- Review the total resource capacity represented by the range, based on the current node size and cache per node.
- Click Enable.
Disable Auto Scaling
- Open Scaling Mode for the cluster.
- Select Auto Scaling.
- Click Disable.
Disabling Auto Scaling stops workload-based adjustments and retains the current number of nodes. You can then use Manual Scaling to make a one-time change, or Scheduled Scaling to configure the days, execution times, and target node counts.
Monitor the cluster
Use Resource Overview in the cluster details panel to review CPU utilization, memory utilization, disk cache utilization, and disk cache hit rate. Click a metric to view a longer time range.
You can also open the cluster on the Metrics page:
- In the upper-right corner, click ....
- Click View metrics.
If the cluster frequently reaches Maximum number of nodes, consider increasing the maximum if the additional cost is acceptable. If the cluster's normal workload needs more capacity, increase Minimum number of nodes.
How Auto Scaling works
VeloDB Cloud regularly evaluates CPU and memory utilization to determine whether to scale the cluster. It adjusts the number of nodes within the configured range.
Evaluation windows
VeloDB Cloud evaluates two time windows to balance fast response with stability:
- Short window (3 hours): Detects sudden changes in demand and allows the cluster to scale in when demand decreases.
- Long window (30 hours): Accounts for daily peaks so the cluster can scale out to a suitable capacity without moving through multiple smaller steps.
Each window recommends scaling out, scaling in, or keeping the current node count. VeloDB Cloud combines the recommendations into one scaling decision.
Utilization watermarks
Utilization that exceeds the high watermark produces a scale-out recommendation. Utilization that falls below the low watermark produces a scale-in recommendation. Utilization between the watermarks produces a recommendation to keep the current node count.
CPU and memory use these default watermarks and utilization targets:
| Resource | Low watermark | High watermark | Target utilization |
|---|---|---|---|
| CPU | 37.5% | 75% | Approximately 53% |
| Memory | 40% | 80% | Approximately 57% |
VeloDB Cloud evaluates CPU and memory independently and selects the larger target capacity. This prevents low CPU utilization from triggering scale-in when the workload still needs memory. High CPU utilization can trigger scale-out even when memory utilization remains stable.
Capacity limits
Auto Scaling changes the number of nodes rather than the size of each node. The configured minimum and maximum node counts bound the cluster's capacity.
For example, with a Node Size of 8 vCPUs and 64 GiB RAM, a range of 1 to 3 nodes provides 8 to 24 total vCPUs and 64 to 192 GiB total RAM. If Cache per Node is 100 GiB, total cache capacity ranges from 100 to 300 GiB. These are example values, not defaults.
Stability safeguards
Auto Scaling uses two safeguards to limit repeated scaling as demand fluctuates:
- Cooldown period: After a successful scaling event, VeloDB Cloud waits 15 minutes before making another change. Newly created or restarted clusters also have a 15-minute warm-up window before Auto Scaling can adjust their capacity.
- Window conflict resolution: When the short and long windows recommend different directions, VeloDB Cloud prioritizes the long window when the short-window trend is rising. When the short-window trend is flat or falling, it prioritizes the short window.
Monitor and tune Auto Scaling
Activity Logs record each Auto Scaling event, including its timestamp, scaling direction, and cluster size before and after scaling. After changing the node count range, review these logs to check whether scaling frequency and capacity meet your workload needs.
If the cluster repeatedly reaches Maximum number of nodes, increase the limit or use Manual Scaling before a known short-term peak. If capacity stays at Minimum number of nodes during recurring quiet periods, consider reducing the minimum.
Best practices
- Set Minimum number of nodes to support baseline demand. A value that is too low can require several scaling events during a sudden spike. A value that is too high reduces savings during quiet periods.
- Set Maximum number of nodes to allow for demand spikes while staying within your budget.
- Before an important launch, campaign, or migration, increase Minimum number of nodes and restore the original value after the event.
- Review Activity Logs regularly to adjust the node count range based on scaling history.
- Use the node count range allowed by the console for your cluster. Contact VeloDB Cloud Support to request a higher compute quota.