Overview of ZFS Snapshots in Unraid
ZFS (Zettabyte File System) is a powerful file system that offers advanced features such as snapshots, which are crucial for data management and recovery. Implementing ZFS on Unraid can enhance your storage capabilities, particularly for users looking to maintain robust data integrity and backup solutions. This guide will provide a detailed approach to setting up and managing ZFS snapshots within an Unraid environment.
Setting Up ZFS on Unraid
Prerequisites
- Unraid Installation: Ensure you have Unraid installed and running.
- ZFS Plugin: Install the ZFS plugin from the Unraid Community Applications.
- Scripts and Cron Jobs: Familiarize yourself with setting up scripts and cron jobs, as these will be essential for automating snapshot creation.
Creating a ZFS Pool
To begin using ZFS, you need to create a pool:
zpool create mypool raidz /dev/sdX /dev/sdY /dev/sdZ
Replace mypool with your desired pool name and /dev/sdX, /dev/sdY, /dev/sdZ with your disk identifiers.
Managing ZFS Snapshots
Creating Snapshots
Snapshots in ZFS are read-only copies of the file system at a specific point in time. To create a snapshot, use the following command:
zfs snapshot mypool/dataset@snapshot_name
Replace mypool/dataset with your dataset name and snapshot_name with a descriptive name for the snapshot.
Automating Snapshot Creation
To automate the creation of snapshots, you can use a script combined with cron jobs. Below is an example script that creates snapshots at specified intervals:
#!/bin/bash
# zfs-auto-snapshot.sh
# Define variables
POOL="mypool"
DATASET="dataset"
SNAPSHOT_NAME="$(date +%Y-%m-%d_%H-%M-%S)"
# Create snapshot
zfs snapshot ${POOL}/${DATASET}@${SNAPSHOT_NAME}
Save this script in a directory such as /mnt/user/scripts/zfs-auto-snapshot.sh, and make it executable:
chmod +x /mnt/user/scripts/zfs-auto-snapshot.sh
Setting Up Cron Jobs
To schedule the script, edit the crontab:
crontab -e
Add the following line to run the script daily at midnight:
0 0 * * * /mnt/user/scripts/zfs-auto-snapshot.sh
This will ensure that a new snapshot is created every day.
Managing Snapshot Retention
To manage how many snapshots you keep, modify your script to include logic for deleting old snapshots. For instance, to keep only the latest 28 snapshots:
#!/bin/bash
# Define variables
POOL="mypool"
DATASET="dataset"
SNAPSHOT_NAME="$(date +%Y-%m-%d_%H-%M-%S)"
# Create new snapshot
zfs snapshot ${POOL}/${DATASET}@${SNAPSHOT_NAME}
# Delete old snapshots, keeping only the latest 28
zfs list -H -o name -t snapshot | grep "${POOL}/${DATASET}@" | sort | head -n -28 | xargs -r zfs destroy
Accessing Snapshots via Samba
To access snapshots through Samba, configure your SMB settings in Unraid:
- Navigate to Shares > Add Share.
- Set up the share path to your dataset.
- Add the following configuration in the SMB settings:
[data]
path = /mnt/user/mypool/dataset
browseable = yes
guest ok = yes
writeable = yes
read only = no
create mask = 0775
directory mask = 0775
vfs objects = shadow_copy2
shadow: snapdir = .zfs/snapshot
shadow: sort = desc
shadow: format = zfs-auto-snap_%S-%Y-%m-%d-%H%M
shadow: localtime = yes
This setup allows users to browse snapshots through Samba shares.
Monitoring and Scrubbing Pools
Regularly monitor your ZFS pools using:
zpool status -v mypool
Additionally, perform scrubs periodically (recommended monthly) to ensure data integrity:
zpool scrub mypool
Conclusion
Implementing ZFS on Unraid provides users with powerful data management capabilities through its snapshot feature. By automating snapshot creation and retention management, users can ensure their data is consistently backed up and recoverable. Regular monitoring and scrubbing of pools further enhance data integrity, making ZFS an excellent choice for advanced users looking to optimize their Unraid systems.