# SnapRAID & MergerFS Storage Setup

## Problem

Managing a collection of mismatched hard drives as a single pool while maintaining data redundancy (parity) without the overhead or risk of a traditional RAID 5/6 array.

## Solution

A combination of **MergerFS** for pooling and **SnapRAID** for parity. This is ideal for "mostly static" media storage (like MajorRAID) where files aren't changing every second.

### 1. Concepts

- **MergerFS:** A FUSE-based union filesystem. It takes multiple drives/folders and presents them as a single mount point. It does NOT provide redundancy.
- **SnapRAID:** A backup/parity tool for disk arrays. It creates parity information on a dedicated drive. It is NOT real-time (you must run `snapraid sync`).

### 2. Implementation Strategy

1. **Clean the Pool:** Use `rmlint` to clear duplicates and reclaim space.
2. **Identify the Parity Drive:** Choose your largest drive (or one equal to the largest data drive) to hold the parity information. In my setup, `/mnt/usb` (sdc) was cleared of 4TB of duplicates to be repurposed for this.
3. **Configure MergerFS:** Pool the data drives (e.g., `/mnt/disk1`, `/mnt/disk2`) into `/storage`.
4. **Configure SnapRAID:** Point SnapRAID to the data drives and the parity drive.

### 3. MergerFS Config (/etc/fstab)

```fstab
# Example MergerFS pool
/mnt/disk*:/mnt/usb-data /storage fuse.mergerfs defaults,allow_other,cache.files=off,use_ino,category.create=mfs,minfreespace=20G,fsname=mergerfsPool 0 0
```

### 4. SnapRAID Config (/etc/snapraid.conf)

```conf
# Parity file location
parity /mnt/parity/snapraid.parity

# Data drives
content /var/snapraid/snapraid.content
content /mnt/disk1/.snapraid.content
content /mnt/disk2/.snapraid.content

data d1 /mnt/disk1/
data d2 /mnt/disk2/

# Exclusions
exclude /lost+found/
exclude /tmp/
exclude .DS_Store
```

---

## Maintenance

### SnapRAID Sync

Run this daily (via cron) or after adding large amounts of data:

```bash
snapraid sync
```

### SnapRAID Scrub

Run this weekly to check for bitrot:

```bash
snapraid scrub
```

---

## Tags

#snapraid #mergerfs #linux #storage #homelab #raid