---
title: General settings
slug: reference/general-settings
docTags: -YbETaVRDs-7kidtw13bV
createdAt: 2025-09-03T13:57:21.925Z
---

Available at **Configuration > General**, are the following fieldsets:

## API

:::hint{type="warning"}
The information configured here will be incorporated in the Token when configuring collectors. If any of these are changed, existing collectors will need to have their token updated. These settings are only used by the collectors, the historian itself will use the values configured in the configuration file.
:::

### GRPC port

**Description:** The gRPC port is the TCP port used by the historian server to communicate with factry collectors. This should reflect the value entered for GRPC\_PORT variable in the configuration file `/etc/systemd/system/environments/factry-historian-server`. **Default:** 8001

### REST port

**Description:** The REST port is the TCP port on which the historian server REST API and management interface is exposed. This should reflect the value entered for PORT variable in the configuration file `/etc/systemd/system/environments/factry-historian-server`, unless you are using a reverse proxy in front of Factry Historian, in which case this should reflect the port that is exposed by your reverse proxy.
**Default:** 8000

### URL

**Description:** This value is used by the factry collectors to derive the ip address to communicate with the historian server API. A valid and reachable URL is required here for collector communication to work.
**Default:** http\://localhost

### API request timeout

*Available from version 8.2 and later.*

**Description:** A server-wide upper bound on how long an HTTP request may take. It is raised implicitly when the user query duration limit under Admission control exceeds it.
**Default:** 2m
**Minimum:** 1s

## Authentication

### Session inactive duration

**Description:** The time after which an inactive login session expires. This setting accepts duration string literals, eg `1w2d7h15m` (1 week 2 days 7 hours and 15 minutes).
**Default:** 7d

## Statistics

### Allow historian to send statistics

**Description:** This setting will enable the historian server to send statistics to our [Portal](docId:29Rc0yqXA3SYqos99T7zK). If this setting is disabled, automatic monitoring and alerting will not work.
**Default**: true

## Collector Updates

### Allow historian to check for updates

**Description:** If enabled the historian server will check for updates to the collectors.
**Default:** true

### Update check interval

**Description:** The interval at which the historian server will check for updates to the collectors. This setting accepts duration string literals, e.g., 1w2d7h15m (1 week 2 days 7 hours and 15 minutes).
**Default:** 1h

## General Logs

### Minimum Free Space (MB)

**Description:** The minimum free disk space in MB required to log to disk. If the free disk space falls below this threshold, logs will be dropped.
**Default:** 2048

### Limit logs

**Description:** If enabled, logs sent to the internal database will be rate limited.
**Default:** true

### Log Rate

**Description:** The maximum allowed number of logs per second. If this threshold is exceeded, logs will be dropped.
**Default:** 50

### Log Burst

**Description:** The maximum number of log lines that can be sent in a single burst. This is used to allow a temporary spike of logs.
**Default:** 500

### Limit By Level

**Description:** If enabled, the log rate limit will be applied to each log level separately. If disabled, the limit will be applied to all logs regardless of their level.
**Default:** true

## Audit Logs

### Duration to keep audit logs

**Description:** The duration to keep the audit logs. This setting accepts duration string literals, e.g., `1w2d7h15m` (1 week 2 days 7 hours and 15 minutes). Set to `0d` to keep indefinitely.
**Default:** 0d

## Admission control

*Available from version 8.2 and later.*

Admission control limits how many time series database queries run at once, how many may wait, and how long any one query may take. Queries are split into two categories, each with its own limits:

- **User queries** are the queries that arrive over the API, from Grafana, the Excel add-in, or the query API directly.
- **System queries** are the queries the Historian runs itself, for calculations and event processing.

When a category is saturated, further queries of that category are queued. When its queue is full as well, the request is rejected with a rate-limit error code. The two categories do not share slots, so heavy dashboard use cannot starve calculations, and vice versa.

### User queries

**Admission control enabled**: If enabled, user queries are rate-limited according to the settings below.
**Default:** enabled

**Maximum concurrent queries**: How many user queries may be performed in parallel.
**Default:** 2 \* number of CPU cores, or 16, whichever is larger

**Maximum queued queries**: How many user queries may be queued on top of all the parallel queries before rate-limit error codes are returned.
**Default:** 3 \* the default maximum concurrent queries, or 50, whichever is larger. The default is derived from the CPU count, not from a maximum concurrent value you set yourself.

**Maximum query duration**: How long any one user query may take before it is aborted.
**Default:** 30s

### System queries

**Admission control enabled**: If enabled, system queries are rate-limited according to the settings below.
**Default:** enabled

**Maximum concurrent queries**: How many system queries may be performed in parallel.
**Default:** 3 \* number of CPU cores, or 24, whichever is larger

**Maximum queued queries**: How many system queries may be queued on top of all the parallel queries before rate-limit error codes are returned.
**Default:** no limit

**Maximum query duration**: How long any one system query may take before it is aborted.
**Default:** 10m

## Time-series Cache

### Enabled

**Description:** If enabled, the historian will cache time series data in memory. This will speed up queries but will consume more memory.
**Default:** true

### Global cache size

**Description:** How many points to keep at most in the global cache. Measurements that produce more data will consume more memory, up to the measurement cache size limit.
**Default:** 4194304

### Measurement cache size

**Description:** How many points to keep at most in the cache per measurement. This cannot exceed the global cache size.
**Default:** 4096