Disks

I had the good fortune to get a nice deal on some Seagate EXOS hard drives from serverpartdeals.com

These are "manufacturer-recertified" HDDs, so they used to live in a datacenter somewhere.

SMART testing the disks

It stands for Self-Monitoring, Analysis and Reporting Technology"

This is a self-reporting diagnostic tool provided by a drive's firmware.

You can also try writing 0 to every single sector on the drive and see if any sectors are not all 0.

Tools

I tried badblocks originally, but it can't handle a hard drive with more than 2³² blocks.

In a pinch, Arch Wiki recommends smartctl or writing 0 to the device. I decided on a long smart test.

      # could also write 0s
      # cryptsetup open /dev/sda new_hard_drive_1 --type plain --cipher aes-xts-plain64
      # shred -v -n 0 -z /dev/mapper/new_hard_drive_1
      # cmp -b /dev/zero /dev/mapper/new_hard_drive_1
      man smartctl # is your friend
      # Decided to use smartmontools
      # Sketches me out that it was recognized at /dev/sda. Nevertheless.
      sudo smartctl -t long /dev/sda # starts long test, it says to wait 1742 minutes (~29 hours) to finish. I started
      about 2025-01-08 13:00.
      sudo smartctl -a /dev/sda # "Print a large amount of SMART information for drive /dev/sda"
    

Power draw

HDDs draw both 5V and 12V power; spinning a platter 7200 times a minute is hard work.

Based on the product manual for my HDDs, that looks like:

Board

Power

Assuming I want to scale this out to 5 drives at some point, and erring on the side of caution:

I would need at least 30 W of 5V, and 150 of 12V

Even with a couple of fans, 200W might be enough. that's a pretty small PSU.

: : : :

I decided to go with a Corsair CX-550

Putting it all together

I wasn't sure how to set my disks up -- I have two to spare for this (I'm using my 3rd in my desktop)

However, I found a rather helpful reddit post:

I have a few Synology NASes here. With the last one, a RackStation 1619xs+, as an experiment, I started with two drives and expanded the array from RAID type to RAID type. I started with a simple mirror, RAID 1. I added another drive and changed the RAID type to RAID 5. The machine rebuilt the array to incorporate the new drive. There was no data lost. I then added additional drives until there were eight. After the array was rebuilt incorporating the new drives, I converted it to RAID 6, which required me to add a ninth drive. The conversion of RAID 5 with eight drives to RAID 6 with nine drives took almost exactly three months. I did not use the NAS during that time, though I could have. I all cases, I was able to expand the array and add drives as necessary or desired. There was never any data loss.

So, I'll start with RAID 1, which is simple mirroring.