How Zerops scales PostgreSQL
Zerops performs an automated scaling of hardware resources required to run your database based on its usage. If the current use of your database does not require as much performance or disk space the auto scaling reduces the resources and thus reduces the costs. If your database is under heavy load or needs to store more data, then auto scaling increases the resources for the database to make sure it runs smoothly.
Configure auto scaling​
To change the auto scaling settings go to the PostgreSQL service detail and choose Automatic scaling configuration in the left menu.
CPU Mode​
Shared Your database gets a full physical CPU core, but it is shared with up to 10 other applications. In this mode the power your database gets is depended on other applications running on the same CPU core. At best case scenario your database gets 10/10 of CPU core power and 1/10 at worst case scenario.
Dedicated The CPU core is dedicated to your database.
See the pricing for the difference between CPU modes.
Choose the CPU mode when starting a new service or change it later. The CPU mode doesn't change automatically.
Vertical auto scaling​
Vertical auto scaling has following default configuration:
| Â | Minimum resource | Maximum resource |
|---|---|---|
| CPU cores | 1 | 5 |
| RAM | 0.25 GB | 8 GB |
| Disk | 1 GB | 2.5 GB |
For most cases, the default parameters will work without issues. If you need to limit the cost of the PostgreSQL service, lower the maximal resources. Zerops will never scale above the selected maximums.
When you are experiencing problems with insufficient PostgreSQL performance or capacity, increase the minimal resources. Zerops will never scale below the selected minimums.
Learn more about how to fine tune the auto scaling to fit your database needs.
Learn more about PostgreSQL auto scaling.
Fine-tune the auto scaling​
Advanced CPU settings​
If you've experienced problems with not enough power when your database starts, increase the default Start CPU core count. Alternatively switch the CPU mode to dedicated to allocate the stable CPU power to your database.
If your database doesn't need so much power after it is started, Zerops will scale down the allocated CPU cores to the defined minimum.
You can disable the CPU vertical auto scaling by setting the minimum and maximum to the same value. This setting doesn't affect the RAM and Disk scaling. Zerops scales each hardware resource independently.
Advanced RAM settings​
The default minimum free RAM is preset according to the database type and version. This setting will ensure that most applications will run smoothly. Zerops monitors the minimum free RAM every 10 seconds.
But if your database need a more memory faster or if you have experienced problems with insufficient memory or even restarts due to Out Of Memory (OOM) errors, we recommend
- Increasing the minimum RAM for the auto scaling
- or increasing the minimum free RAM in GB
- or setting the minimum free RAM in % of the RAM assigned to the container
You can set the minimum free RAM both in GB and in percent, Zerops will apply the larger value based on the current RAM assigned to the container.
You can disable the RAM vertical auto scaling by setting the minimum and maximum to the same value. This setting doesn't affect the CPU core and Disk scaling. Zerops scales each hardware resource independently.
Technical details​
Automatic scale up​
Zerops monitors CPU, RAM and Disk usage in all running containers each 10 seconds. The scale up threshold is derived from following minimum free resources:
- 0.1 CPU core
- 0.25 GB RAM (You can fine tune this setting)
- 0.5 GB disk
If the minimum free CPU, RAM or disk usage of a container is lower than the defined scale up threshold, Zerops scales the container up.
The scale up of RAM or disk is immediate. The scale up of CPU is configured to be a little less aggressive. Two consecutive measurements of free CPU with values under the scale up threshold are required to trigger the scale up. This rule prevents excessive fluctuations of scaling up and down due to sudden changes in CPU usage.
The minimum step for the vertical scaling is
- 1 CPU core
- 0.25 GB RAM
- 0.5 GB disk
When the database is under a heavy load and needs to scale up faster, the scaling step will increase automatically.
Maximal resources are defined for each PostgreSQL service. Zerops will never scale above the entered values. If your database is in [highly available mode], maximal resources are identical for all containers of the PostgreSQL service.
Not enough resources to scale up​
Zerops moves a container between physical machines only if there are not enough resources on the current physical machine to scale the container up. When this happens the behaviour is different for highly available and single container mode.
Automatic scale down​
When the database no longer needs as much power or disk space, each container is gradually scaled down to the defined minimum. The automatic scale down is configured to be more cautious and defensive to prevent the database from scaling up and down rapidly.
Consecutive measurements during:
- 1 minute for CPU
- 2 minutes for RAM
- 5 minutes for disk
with free resources safely above the minimum threshold are required to scale down the appropriate resource.
The minimum step for the scale down is identical to the minimum step for scale up. When several scale down events are triggered in a short period of time, the scaling step increases automatically.
Horizontal scaling​
Zerops provides PostgreSQL service in two modes: Highly available and Single container. The PostgreSQL service mode is chosen when creating a new service and cannot be changed later.
Zerops doesn't scale PostgreSQL service horizontally, it means no containers are added or removed from the database cluster. Only in case of a failure of a container or the underlying physical machine, Zerops automatically replaces the broken container with a new one.
Monitor database resources​
Zerops provides information about how much hardware resources the PostgreSQL service is currently using. Go to PostgreSQL service detail in Zerops GUI and select Service dashboard & database containers in the left menu. Zerops also provides the history of resource usage.