Domain Folder Synchronizator (dfsync)

Table of Contents

Description
Limitations
Parameters
Configuration example
See also

Description

A service role that provides synchronization of :SYNC directory files between different servers on the system. Communication between sites provides without direct connection of the type full-mesh. Tracks file system changes for each directory according to directory mapping to domains, and provides propagation to all site servers serving the respective domains. The :SYNC/common directory is synchronized across all sites.

It is fundamentally non-redundant, covering the entire server network with instances. There is no need to use a microservice in a single-server configuration.

Receives notifications of file system changes using the package inotify-tools. Files are reconciled by date and size. Content hash sums are not applied for performance optimization purposes.

At startup, reads the directory structure and creates a cache, and then regularly monitors the synchronization status with other servers in the group. If necessary (mismatch of hexameters), each instance performs a one-way synchronization to its own side. The cache is stored on disk, among other things. When files are deleted, information about it is stored in the cache for 1 year.

Table 1. System Characteristics

Code	`dfsync`
Mode of operation	`Service`
Backup mode	`Active-Active`
Types of sites	`All of them`
Layer	`Configuration`
Placement	`Internal`
Saving and restoring state on reboot	`Yes`
appendix	`era_dfsync`

Limitations

Not present in the initial single-server configuration.
Must be present 1 time on each server.
In a configuration with more than 1 site, each site at least one instance must have the `is_cross_site` feature enabled to ensure data synchronization with other sites. If more than one trait is enabled, each pulls data from other sites independently, increasing the channel load.

Parameters

Description of columns in the table

Table 2. Parameters
Name	Type	Default	Description
`name`	`str`	required	Name. May consist of Latin letters and numbers, must begin with a letter.
`roletype`	`str`	required	Role Type. Possible values: `"dfsync"`.
`iface`	`str`	required	The alias of the server network interface on which the roles will interact internally with each other.
`ext`	`json`	empty	Additional role options. Contains a json object or list.
`enabled`	`bool`	empty	Role activity flag. When set to false, the role does not participate in validation and is not started.
`is_cross_site`	`bool`	`false`	An indication of placement on a node server that provides connectivity to other sites.
`roleid`	`int`	required	Role ID. Unique for the entire system, regardless of the site or server. Cannot be changed. Integer from `1` to `9999`.
`separate`	`bool`	required	An indication that the role has been allocated to a separate node.

Configuration example

The configuration is managed in an application available to master domain administrators. The application hides the full content of the configuration, but it is nevertheless accessible via the API.

The configuration contains a section to describe all instances of all roles. Parameters are defined for each specific role instance.

Example node

{
  "name": "dfsync1",
  "iface": "eth0",
  "is_cross_site": false,

  "roleid": 11380,
  "roletype": "dfsync",
  "separate": true
}

Domain Folder Synchronizator (dfsync)

Description

Limitations

Parameters

Configuration example

See also