# Running several instances at once

> How Settings Saver keeps its store consistent when several Minecraft instances run at the same time, and whose change wins when two of them sync.

URL: https://xichil.dev/wiki/settings-saver/v0/mechanics/multiple-instances/ · Updated: 2026-11-06 · Applies to: Fabric, Quilt, Legacy Fabric, Forge, NeoForge, MC 1.7.10 - 26.3

You can run several instances with Settings Saver at the same time, on the same or different
Minecraft versions and loaders. They share one [store](https://xichil.dev/wiki/settings-saver/v0/guides/store-location/index.md) without corrupting
it or undoing each other's changes.

## Locking and safe writes

Every time an instance reads, changes and writes the store (Save, Load, auto sync, profile changes),
it holds a lock: one inside the game and one on the `.lock` file in the store, which other running
games respect. Files are written to a temporary file first and then moved into place in one step, so
a crash or a closed game never leaves a half-written file behind.

## Whose change wins

In the Auto modes each instance saves only the settings **you changed in it** since it last synced,
never its whole file. So with two instances on Auto:

- You change FOV in instance A and render distance in instance B. The profile gets both.
- You change FOV in A, then FOV in B. The profile has B's value, the last change.

Pressing **Save** in an instance writes every setting of that instance that differs from the profile,
so a Save can replace a change another instance synced earlier.

## Seeing another instance's changes

A running instance doesn't reload the profile when another instance changes it. It picks up the
changes:

- when you press **Load settings from profile**, or
- at its next launch, in the **Auto + always apply** [sync mode](https://xichil.dev/wiki/settings-saver/v0/mechanics/sync-modes/index.md).

## Instances on different profiles

Each instance syncs only with its own profile, so a `pvp` instance and a `default` instance never
touch each other's settings. When you switch an instance to another profile, it starts saving its
later changes into the new profile.