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Build a fault-tolerant infrastructure

This instruction describes how to increase the fault tolerance of your service at the physical level.

Fault tolerance is the ability of a service to remain operational and continue performing business tasks even if individual components of the IT infrastructure fail.

The service's level of fault tolerance depends on the type of tasks being performed. The need to increase fault tolerance arises when the cost of downtime exceeds the cost of ensuring uninterrupted operation. For example, if the service provides continuous access to critical information, or if company operations depend directly on the uninterrupted performance of IT infrastructure.

What Selectel provides

Selectel ensures the fault tolerance of your service at the level of the server room where server racks are located.

Power supply

Power inputs enter the server room, redundant at higher levels (Selectel transformer substations; industrial UPSs including battery arrays; emergency power source — diesel generator sets), then two independent power feeds are supplied to each rack:

  • for servers with a single power supply, ATS (automatic transfer switch) devices are installed in the racks, to which two independent power inputs are connected; if one input is disconnected, power will continue to be supplied through the second;

  • for servers with two power supplies, they are connected to two independent power strip blocks.

Access to private network and the internet

Access to the private network and the internet is redundant at the aggregation switch level and above, as well as:

  • for pre-configured servers, access switches for the private network and internet switches are installed in each rack;

  • for some Chipcore Line servers, there is no private network connection, and only internet switches are installed in each rack;

  • for custom-configuration servers, you determine the redundancy of the connection to the required network (private or internet) yourself.

Location in racks

If technically feasible, when ordering two or more servers, they are placed in different racks. You can view the current server location and submit a request to move a server to another rack in the Control panel: in the top menu, click Products and select Dedicated Servers → Servers → Server location tab.

Increase fault tolerance

You can increase the fault tolerance of a client service at the physical level by reducing the number of potential points of failure. When building IT infrastructure, potential points of failure can include:

  • the server itself and its components (drives, power supplies, network interfaces, etc.);
  • ATS (automatic transfer switches);
  • internet access switch and switching (copper and optical connections, transceivers, patch cords, etc.);
  • access switch to the private network and switching.

Increase fault tolerance at the rack level

To reduce the number of potential points of failure at the rack level, you can:

  • choose servers of custom and prebuilt configurations with server-grade processors. All components in such servers are optimized for high loads and smooth operation, making them less likely to fail;
  • use a server configuration with two or more power supplies. This power redundancy method is more reliable as it eliminates a single point of failure. Failure of one power supply or ATS will not lead to server shutdown;
  • for custom servers, make the connection to access switches of the required network (private or Internet) redundant via MC-LAG;

Increase fault tolerance of a client service consisting of multiple servers

To reduce the number of potential points of failure for your service hosted on multiple servers, you can: