I have an old QNAP TS-431K NAS. I replaced some 8 TB HDDs in it with 16 TB ones. I’m using some internal volume as storage for regular backups, like the Time Machine for my Mac. But I find it makes the drive active like crazy.
To reduce the wear and tear on the internal HDDs, I decided to reuse of the 8 TB drives as an external one, plugged in via USB. I wanted to use half of it for Time Machine and the other half for other backups.
But like I said… my NAS model is old and, to my surprise, with all the tools and options it offers for formatting and setting up RAID arrays, its Web GUI just doesn’t offer ways to partition an external drive.
To make things worse, when I try to partition the drive on my Mac, and then try to format the volumes with the NAS, it chokes and stays with “Formatting 0%”…
Fortunately, via the terminal, I found a way to find the drive, partition it, format the volumes, and even encrypt them.
However, before I begin, a warning…
⚠️ WARNING! Doing the following will destroy any data you have on your external drive. If the instructions are incorrectly followed, they may also lead to data loss on your internal drives. In any case, the details below are provided as-is, and I cannot be held responsible for any damages that may occur from following the instructions below.
Finding the drive
First, eject the drive from the GUI.
Then, while connected to the terminal of the NAS via SSH, plug the drive back in, and try the following:
dmesg | tail -n 20 | grep Attached
If it works, it should display something like this:
[ 5096.475384] sd 10:0:0:0: [sde] Attached SCSI disk
The middle part in square brackets ([]) is the name of the device. In my case, sde. So it can be found as /dev/sde.
Then, if the drive has any partitions already, you may want to confirm them:
cat /proc/partitions | grep sde
Partition the drive
By now, the GUI probably tried to mount the drive again. Eject it from there one more time. It won’t show up in the GUI anymore, but it will still be accessible via the terminal.
The drive I have has a large capacity. While fdisk is popular, it can’t handle that drive, as it’s mostly made to handle Master Boot Record (MBR) partition tables, which only works for drives of up to 2 TB.
In this case, we’ll use parted. Remember, my drive is /dev/sde but yours may be different. First, we’ll use it to list any partition table the drive may already have, which should be similar to /proc/partitions earlier:
parted /dev/sde --script print
Then, we’ll make a new GUID Partition Table (GPT), then two partitions of equal size, both made to handle the Linux ext4 file format:
parted /dev/sde --script mklabel gpt
parted /dev/sde --script mkpart primary ext4 0% 50%
parted /dev/sde --script mkpart primary ext4 50% 100%
As we made two partitions, that will create the numbered drives in /dev. In my case, /dev/sde1 and /dev/sde2.
Encrypt the partitions
As unlikely it may seem, I wouldn’t want someone to just steal my external drive, mount it on their computer, and just go through all my backup data on it. (Although, I’m quite sure my Time Machine backups are also encrypted on their own.)
Although optional, I still recommend we encrypt the drives before we format. For that, we’ll use cryptsetup to format both volumes, which is basically an encrypted wrapper for the actual ext4 volumes we’ll format in later:
cryptsetup luksFormat --type luks1 --cipher aes-cbc-plain --key-size 256 --hash sha1 --iter-time 500 /dev/sde1
Repeat the above for the second drive, e.g. /dev/sde2.
If you still don’t want to encrypt the partitions, you may skip to Format the volumes below.
Gotcha: Passwords are limited to 16 characters
You’ll be asked to pick a password, or key, to encrypt the volume.
I had some issues with that earlier. Then, I found this in the HTML of the GUI:
<input
type="password"
size="20"
autocomplete="off"
id="ext-comp-3406"
name="ext-comp-3406"
class="x-form-text x-form-field x-form-invalid"
style="width: 128px;"
maxlength="16" />
Ah… Even though luksFormat supports passwords of any reasonable length, QNAP forces you to pick a password of 16 characters or l