Automatic scaling and High Availability
What is automatic scaling?​
Zerops scales your application or a database based on the current load. If your application isn’t used so often the auto scaling reduces the amount of required hardware resources and thus reduces the costs. If your application is used more, then auto scaling increases the resources for the application to make sure it runs smoothly even with the higher demand.
On Zerops, you never pay for resources you don’t need. At the same time you don’t have to worry about traffic peaks or fast growth as the auto scaling feature handles this with no trouble. By default Zerops scales the applications and databases based on the best practices but you are always in control. Set the ranges for the auto scaling and fine-tune the settings so it fits the exact project and environment needs.
Vertical and horizontal auto scaling​
Each application you deploy starts with the minimum hardware resources: CPU cores, RAM and Disk. Zerops monitors the usage of these 3 resources and if the usage exceeds a set threshold, more CPU cores, RAM or Disk is allocated to the service. This is called vertical scaling.
Horizontal scaling adds or removes whole containers.
Zerops has a preference for vertical scaling because it's faster and more precise. If the vertical auto scaling hits the defined maximum a new container is started automatically. When your application doesn't need so much power and all containers are vertically scaled down, Zerops will gradually remove whole containers.
Auto scaling configuration for runtimes​
Both minimum and maximum limits for auto scaling are under your control. Technical minimums for CPU cores, RAM and Disk are preset for each runtime service. Configure the minimums and maximums CPU cores, RAM and Disk depending on the needs of your application and Zerops will scale them within defined limits.
You can change the settings any time, Zerops will update the number of containers and their allocated resources accordingly.
Single container vs. High Availability​
When creating a new runtime service, you can choose the minimum and maximum number of containers. If you set the maximum limit to one, the service will be run in a single container and no horizontal scaling will occur.
By increasing the maximum number of containers for your service, you enable horizontal auto scaling. Zerops will then add containers depending on your application’s load. Application running on two or more containers is in High Availability mode, which we highly recommend for production. When the load drops, containers will be gradually removed to the defined minimum.
Each container of the same service is strictly installed on a different server. This prevents the temporary outage in case any of Zerops servers fail. If the connection to a container is broken, Zerops immediately redirects incoming traffic to other containers. A new container will be started automatically and the broken container will be deleted.
Shared vs. dedicated CPU​
Zerops offers 2 CPU modes:
Shared​
Your application gets a full physical CPU core, but it is shared with up to 10 other applications. In this mode the power your application gets is dependent on other applications running on the same CPU core. At best case scenario your application gets 10/10 of CPU core power and 1/10 at worst case scenario.
Dedicated​
The CPU core is dedicated to your application.
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.
Fine-tune the auto scaling​
Advanced CPU settings​
If you've experienced problems with not enough power when your application starts, increase the default Start CPU core count. Alternatively switch the CPU mode to dedicated to allocate the stable CPU power to your application.
If your application 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​
By default Zerops keeps a minimum free RAM in each container. This setting will ensure that most applications will run smoothly. Zerops monitors the minimum free RAM every 10 seconds.
But if your application 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.
Auto scaling configuration for databases​
Vertical auto scaling configuration for databases is identical to runtime services. Technical minimums for CPU cores, RAM and Disk are preset according to the database type and version.
You can choose 2 modes for each database: Single Container or Highly Available mode. The mode cannot be changed after the database is created.
Database in the Single Container mode​
In the Single Container mode the database is deployed in a single container. The number of containers cannot be increased. This mode is useful for non-essential data or dev environments.
Your data is stored only in a single container. If the container or the underlying physical machine fails, your data since the last backup will be lost. Zerops is not able to provide any automatic repair of single container mode databases.
Database in the Highly Available mode​
If the Highly Available mode is chosen, Zerops will deploy the database cluster with a fixed number of containers and control mechanisms for automatic cluster repair.
The KeyDB (Redis) cluster consists of 2 containers in the master-master replica. MariaDB, PostgreSQL databases and RabbitMQ message broker are deployed in 3 containers connected in the High Availability cluster with 2 additional load balancers which ensures high reliability.
You are not charged for the resources consumed by load balancers.
This mode is highly recommended for production use.
Prevent the data loss by using the HA mode​
Zerops always keeps the database containers on different physical machines. All your data is stored redundantly in 3 identical copies (2 in case of Redis). In case of a failure of a container or the underlying physical machine, Zerops automatically disconnects the failed container from the cluster, creates a new container and syncs all data from the remaining copies. Finally the broken container is automatically deleted.
Auto scaling configuration for shared storage​
Vertical auto scaling configuration for shared storage is identical to database. Technical minimums for CPU cores, RAM and Disk are preset.
You can choose 2 modes for a shared storage service: Single Container or Highly Available mode. The mode cannot be changed after the shared storage is created.
Single Container mode shared storage​
In the Single Container mode the shared storage is deployed in a single container. The number of containers cannot be increased. This mode is useful for non-essential data or dev environments.
Your data is stored only in a single container. If the container or the underlying physical machine fails, your data since the last backup will be lost. Zerops is not able to provide any automatic repair of single container mode shared storages.
Highly Available mode shared storage​
If the Highly Available mode is chosen, Zerops will deploy the shared storage cluster with 3 containers and control mechanisms for automatic cluster repair.
This mode is highly recommended for production use.
Prevent the data loss by using the HA mode​
Zerops always keeps the shared storage containers on different physical machines. All your data is stored redundantly in 3 identical copies. In case of a failure of a container or the underlying physical machine, Zerops automatically disconnects the failed container from the cluster, creates a new container and syncs all data from the remaining copies. Finally the broken container is automatically deleted.