## Description > [!NOTE] > If you’re wondering why hardlinks aren’t working or why a simple move is taking far longer than it should. > > Here we will try to explain it. This guide consists of 4 sections. 1. This page with a short description. 2. [How to set up](https://trash-guides.info/File-and-Folder-Structure/How-to-set-up/) for your installation method. 3. [Examples](https://trash-guides.info/File-and-Folder-Structure/Examples/) What you should use for your path settings in your used applications. 4. [Check if hardlinks are working](https://trash-guides.info/File-and-Folder-Structure/Check-if-hardlinks-are-working/) So you want one of the following? - Instant moves (Atomic-Moves) during import of the Starr Apps (useful when using Usenet)? - You don't want to use twice the storage when using torrents. (hardlinks)? - You want to perma-seed? Then Continue to [How to set up](https://trash-guides.info/File-and-Folder-Structure/How-to-set-up/) for your installation method. ## FAQ ### Hardlinks Limitations > [!CAUTION] > - You CAN'T create hardlinks for directories > - You CAN'T hardlink across separate file systems, partitions, volumes or mounts > - Some file systems, such as exFAT, are known not to support hardlinks and should be avoided (double-check if you are unsure!). ### What are Hardlinks > [!NOTE] > **What are hardlinks?** > - [**Short answer**] Having a file in multiple locations without using double your storage space. > - [**Long answer**] Hardlinks allow a copy operation to be instant and not consume space for those additional copies. > > Every file is a hardlink: some metadata that points at blocks on the file system, **which is why they're restricted to the same file system**. There can be as many metadata files pointing at those blocks as needed, and the blocks know how many links point to them. Once the blocks have 0 links, they're considered deleted. > > This means: > > - You can delete any "copy" without impacting other instances (hardlinks). > > Your download client can remove its "copy" without impacting the library "copy". The library "copy" can also be removed by Plex, Sonarr/Radarr, or manually without impacting your download client's "copy". > > - Space is only reclaimed once all "copies" of hardlinked data are deleted. > > - Modifying any copy of a hardlinked file will impact all "copies". > > For example, modifying the id3 tags of a .mp3 download after import would change the download client "copy", breaking the torrent. > > [More info from Wikipedia, the free encyclopedia](https://en.wikipedia.org/wiki/Hard_link) > > > [!WARNING] > > **Don't forget to read the [Hardlinks limitations](https://trash-guides.info/File-and-Folder-Structure/Hardlinks-and-Instant-Moves/#hardlinks-limitations)** ### What are Instant Moves (Atomic Moves) > [!NOTE] > **What are Instant Moves (Atomic Moves)?** > This is a real move, not a copying of a file from the download folder to the media folder and then deleting the file from the download folder. ### What are the Starr Apps > [!NOTE] > **What are the `Starr Apps`?** > Sonarr, Radarr, Lidarr, etc. ### Permissions, ownership, and UMASK > [!NOTE] > **Permissions, ownership, and UMASK** > Hardlinks and instant (atomic) moves require all paths to be on **one filesystem**, but they also depend on **permissions**: every app must be able to read — and the apps that import, upgrade, or delete must be able to write — each other's files. This is governed by the **user and group your apps run as**, the **`UMASK`**, and **ownership** — assumed knowledge here and explained in detail in the [Servarr Docker Guide](https://wiki.servarr.com/docker-guide). > > How the user and group are set depends on the image: many images (for example LinuxServer.io) use the `PUID` and `PGID` environment variables, while others use Docker's native `--user` / `user:` directive (a `uid:gid` pair). Either way, pick one of the two setups below and apply it consistently: > > | Setup | Users | `UMASK` | Resulting default permissions | > | --- | --- | --- | --- | > | **Per-app user + shared group** (recommended) | a separate user per app, all in one shared group | `002` | folders `775` (`drwxrwxr-x`), files `664` (`-rw-rw-r--`) | > | **Single shared user** (simpler, less strict) | one user for every app | `022` | folders `755` (`drwxr-xr-x`), files `644` (`-rw-r--r--`) | > > `UMASK 002` keeps the **group-write** bit, so files and folders created by one app can be read and written by the others. The single-user setup can use `022` because one user owns everything. > > > [!WARNING] > > Don't use `UMASK 000` (folders `777`, files `666`) — it makes everything readable and writable by **everyone**, which is poor Linux hygiene.