Storage (st)

Table of Contents

Description
Limitations
Parameters
Configuration example
See also

Description

Universal site storage. Used by various roles as an internal service.

Reserved in Active-Passive mode. Scalable by partitioning into groups by hash sums of keys.

Table 1. System Characteristics

Code	`st`
Mode of operation	`Storage`
Backup mode	`Active-Passive`
Types of sites	`All of them`
Layer	`Business logic`
Placement	`Internal`
Saving and restoring state on reboot	`Yes`
appendix	`era_store`
Own storage	`ODB Mnesia`

Limitations

Present in the initial configuration.
Must be present at every site.
When a role is unavailable, most services do not function, including the inability to boot the system.

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: `"st"`.
`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.
`group`	`int`	required	Group Number. As part of horizontal scaling, a role can be divided into multiple groups on a site, with only one instance active in each group and the rest reserved. Responsibility between groups is divided by the hash sums of the keys of the stored data. All roles in the same group must have the same responsibility. The calculation of hash sums is done automatically by an internal algorithm with uniform-random distribution. Integer from `1` to `9999999`.
`order`	`int`	required	The order of a role instance within a group. Defines in what order the flow in the mode will take place Active-Passive.
`mnesia_storage_mode`	`str`	`disc` "Mode of operation of object storage.	Possible options:
`* disc - full mode`	`in RAM with saving to disk on all instances of the group.`	ram - only in RAM (with support for distributed	transactional). If all instances of the group are rebooted/shut down simultaneously

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

{
  "st1": {
    "name": "store1",
    "roletype": "st",
    "iface": "eth0",

    "group": "11080",
    "order": "1"
  }
}

Storage (st)

Description

Limitations

Parameters

Configuration example

See also