Mergerfs¶
I use mergerfs to create a "pool" several mixed-capacity drives under one mountpoint. I used to have this as my main storage strategy have switched to ZFS in that situation and now use mergerfs for my second copy. This is because I don't have enough drives to do another zfs pool yet but also because this gives me a little bit of "redundancy" in the sense that I haven't put all my eggs in the zfs basket as it were. That seems appropriate for someone who is still pretty new to ZFS and doing it all manually (not in TrueNAS).
If you want the latest updates, the command below pulls down the latest version of mergerfs from Github instead of relying on the apt repository which tends to lag behind the latest release. You can run it however often you want. If you already have the latest version, it will do nothing.
curl -s https://api.github.com/repos/trapexit/mergerfs/releases/latest | grep "browser_download_url.*$(grep VERSION_CODENAME /etc/os-release | cut -d= -f2)_$(dpkg --print-architecture).deb\"" | cut -d '"' -f 4 | wget -qi - && sudo dpkg -i mergerfs_*$(grep VERSION_CODENAME /etc/os-release | cut -d= -f2)_$(dpkg --print-architecture).deb && rm mergerfs_*.deb
I also like to put the command in an update_mergerfs.sh script and set it to run every 3 months at 3AM on a cron job. Run sudo crontab -e to open the crontab for the root user and then add the following line to the end of the file:
Install inxi to identify your drives.
sudo apt install inxi
inxi -xD # list drives
ls /dev/disk/by-id # list drives by their immutable ids
Then identify the current sdX mappings for each drive:
ls -la /dev/disk/by-id/ata-ST400VN006-3CW104_ZW62V162 # for example
/dev/disk/by-id/ata-ST4000VN006-3CW104_ZW62V162 -> ../../sdb # output
Take note of the mappings. We'll need them for our etc/fstab.
Run sudo su to switch user to root.
For new drives (no pre-existing data you want to keep), run gdisk /dev/sdX where X is the drive you want to format. This will drop you into an interactive session. Follow these instructions:
Press `o` to create a new empty GPT partition table
* Proceed? (Y/N) - Y
Press `n` to create a new partition
* Partition number (1-128, default 1): 1
* First sector (34-15628053134, default = 2048) or {+-}size{KMGTP}: <leave blank>
* Last sector (2048-15628053134, default = 15628053134) or {+-}size{KMGTP}: <leave blank>
* Hex code or GUID (L to show codes, Enter = 8300): 8300
Press `p` to validate that 1 large partition is to be created
* Model: HGST HDN728080AL
* Number Start (sector) End (sector) Size Code Name
* 1 2048 15628053134 7.3 TiB 8300 Linux filesystem
Press `w` to write the changes made thus far
* Until this point, gdisk has been non-destructive
* Confirm that making these changes is OK and the changes queued so far will be executed
After you have done that for all your drives, create an ext4 filesystem on each drive's newly created partition with mkfs.ext4 /dev/sdX1.
Now we can create mountpoints for our new partitions:
mkdir /mnt/disk{1,2} # or however many you need
mkdir /mnt/parity1 # adjust this command based on your parity setup
mkdir /mnt/storage # this will be the main mergerfs mountpoint
Finally, we can edit /etc/fstab to tell our OS to mount our new partitions to our newly created mountpoints. This will run every time our machine boots. Here's an example:
The last line contains numerous mergerfs config options.
In order to reload the new fstab entries you've created and check them before rebooting, use mount -a. Then verify the mount points with df -h. If you had any existing files on your data disks they will be visible under /mnt/storage.
Now's as good a time as any to change the owner of your new mergerfs pool to your non-root user so that when you start using samba and docker, you have write and read permissions at the Debian level: