# ZFS

## Why

london-b is my primary storage server with 8 spinning disks. ZFS was the obvious choice — it gives me data integrity via checksumming, flexible RAID configurations, and built-in snapshot support, all without needing a separate RAID controller.

The alternative (mdraid + ext4 or XFS) works fine but gives up checksumming, which means silent data corruption is possible. With 8 drives and 46+ TB of data, I'd rather know about corruption than discover it years later.

## Current Setup

Pool name: `hdd`

Configuration: 3× RAIDZ1 vdevs (each with 2-3 drives, 8 drives total)

| Metric | Value |
|---|---|
| Used | 46 TB |
| Free | 18 TB |
| Total | ~64 TB |
| Health | Scrub weekly (Sundays) |

RAIDZ1 tolerates one drive failure per vdev. Given the drive count and age, this is the right trade-off between capacity and redundancy.

## Scrubbing

A weekly scrub runs every Sunday. This reads all data and verifies checksums, catching any silent corruption or drive errors early. Scrub results are visible in Grafana via the smartctl exporter.

## Snapshots

ZFS snapshots are used for point-in-time recovery. Fast and space-efficient — snapshots only consume space for data that's changed since the snapshot was taken.

## Notes

ZFS is somewhat memory-hungry (ARC cache). london-b has 64 GB of RAM which gives ZFS plenty of headroom.