A home networked server, what's not to like? It has been decades since I've set up something similar, and as I recently wrote in the Pi-Hole and digital music articles, it was time. It would allow me to have a (1) more than decent backup system and (2) the flexibility to install local services such as Navidrome for streaming my own music.

There are so many things to take into consideration when deciding to build or buy a home server---it's a bit daunting, to be honest, even for a tech person like me. I'll try to list the challenges I was struggling with here along with the approach I've taken to mitigate them.

1. Home built or store bought?

The first major struggle. Should you create your own NAS/server¹ or should you just get a Synology or something similar? That depends on a couple of things. Are you a tinkerer and do you like to fiddle with hardware and networked software? Do you care about power efficiency? Is it important to you to run only exactly the software you want?

Power efficiency. This excellent blog post on "DIY NAS or Synology" sheds light on the (hidden) costs of creating your own machine. If you build your own system, a truly low-powered setup is difficult to achieve. A simple home PC PSU comes with way too much Watts (500+), usually needed to power Ryzen CPUs that easily drain more than 20 W while idling. This is just the CPU: factor in motherboard, RAM, GPU, fans, ... and you've probably doubled that amount². The 2bay DS720+ I ended up buying consumes 16.44 W on access and 6.19 W in hibernation. According to Sugoi's blog post, the difference in power over eight years is a surplus cost of 71%! Given the ridiculous high prices of gas and electricity right now, I'd say store bought definitely wins here, even if you resort to smaller cases.

Our server is powered off between midnight and 7 AM. It's a local-only system, and even if it runs the DHCP and DNS server now, it's a great way to preserve both power usage and internet access at night. Self-constraints for the win!

Software. Synology machines aren't exactly cheap. Just like Apple machines, you do also pay for the provided software (and name, I guess). That said, will you be content with the DiskStation Manager (DSM) OS and its ease of use but weird deviations from a vanilla Linux distribution (what's up with no crontab and the weird /home user placement?)---or do you prefer total control? After poking around in DSM and ssh for a week on the Synology system, I can safely say that there's still ample room for "hacking" if that's your thing. Of course, if most provided by DSM is bloat in your eyes, then by all means go for FreeBSD or Arch.

If you decide to start from scratch, everything is possible, including trying out OpenZFS and different RAID setups (again, provided the technical expertise is there). Synology systems still come equipped with ample solutions for your hard disk needs: the Btrfs file system, hybrid RAID solutions, etc.

Install/config time. Another hidden cost would be the time to install and manage the server. Installing a Synology literally takes two minutes: plug it in, go to synology.local, click on "Install DSM", and done. Installing a Linux distribution---depending on the flavor and hardware compatibility, of course---is slightly more involved. If my system crashes, it's dead easy to restart from scratch. System admins will likely resort to Ansible scripts or something similar to keep their own server in top shape and decrease install/config time, but still, store bought also wins here.

I know that's a very subjective thing. It's the same reason why I stopped compiling everything from scratch with Gentoo Linux and resorted to MacOS: if I want, I can still open up a terminal, and it's still UNIX. Sure, that's completely different, and I won't get into licensing and other issues here, but my time is valuable, and I also have hobbies that do not have anything to do with tech. Deep down, as a tech nerd, I still wish I built it from scratch, but I'm content with what is now.

2. How many drive bays?

Growth factor. That'll entirely depend on how much garbage---erm, data---you've accumulated over the years. We don't have a lot. I tried calculating how much we'd need and how long we'd be able to work with x amount of terabytes, by dividing our data into the following categories:

• Music albums. Currently 1 GB. The average album is about 90 MB. If we add two a month, that's about 2.2 GB/year.
• My work git projects. Total size divided by how many years I've been working on it = 500 MB/year for a big one and 166 MB/year for Brain Baking, for instance. Multiply by ten or so projects? = another 2.1 GB/year.
• My digital notes. Currently 1.6 GB, add about 0.2 GB/year.
• Time machine backups. Two laptops, 1 TB rotated, fixed.
• Existing miscellaneous stuff on a USB SSD: 64 GB, fixed.
• Existing DVDs we plan to rip and put on it: 80 GB, fixed.
• Photos. The average album is 400 MB, times six a year = 2.4 GB/year.

That's a baseline of let's say (rounded up) 1.2 TB + 7.5 GB yearly. Let's play it safe and double that yearly amount: 15 GB of added data, yearly. Now let's play it even safer and add a yearly inflation of 20%. The first five years, that would be 15 + 18 + 21.6 + 25.9 + 31.1 = 111.6 GB in five years.

Right, so how much do hard disks costs? At first, I wanted to go for SSDs, not because of the speed or reliability, but because of the noise! There are data sheets available for that kind of info, as are for reliability, such as the well-known Backblaze hard drive stats. At the moment, 4 TB of NAS storage (slightly more expensive than a regular HDD) costs about €95. Will four tera suffice? 111.6 GB is 9% of a terabyte! Even within ten years, I cannot see how I can fill that entire disk. The Backblaze buyers guide features a capacity calculator formula, but the growth factor multiplier there is just ridiculous.

RAID setup. Another important note: HDDs are known to eventually fail. To protect your data, you're best off installing multiple hard drives that function as a carbon copy. In case one fails, the other takes over. This is called a "RAID" setup, and there are multiple possibilities here. Of course, with only two bays, you're limited to RAID-1: one HDD is an exact copy of the other. That means that if you buy 2 x 4 TB, there's not 8 TB but only four available for you. If you buy a 4-bay system, you can resort to a hybrid setup or RAID-5: only one HDD will function as a copy, and there's room for expansion. The DS720+ does offer an external port that can connect with an (expensive) expansion bay, and two USB 3.0 ports that can connect 1 TB USB HDDs.

If you were to rely on SATA SSDs, a Western Digital Red SA500 NAS SATA costs about €525 for 4 TB. Ouch! Just 1 TB is still about €120, and you'd need two of them for a RAID setup. Just one tera is more than the fixed data we already have, so that's a no-go. Mechanical drives it is---just make sure to dump that server in the basement or somewhere where the HDD rattle doesn't bother you.

Unless I've made a grave mistake, two bays with 4 TB disks more than suffices for us. The extra cost of four bays---"just in case"---from DS720+ to DS920+ (delta of about €120) is just not worth it.

3. How much computing power?

Services. What are you planning to run on it? Synology's home NAS solutions come with either 2 or 4 CPU cores, and usually with only 2GB of DDR4 RAM. That's kind of meager, but should be enough if backup and storage is your priority. However, if you plan to deploy a lot of Docker containers, expect to buy a SODIMM RAM expansion. A home grown solution clearly shines here. Official "Synology memory" is very expensive (€90 for 4 gigs, what the hell??), and these machines are very finicky when it comes to RAM compatibility. Believe me, I've tried. A reliable Kingston DDR4 stick for €30 made the system crash every few hours.

I went with the DS720+ instead of the lower priced 220+ for the extra juice as running PhotoPrism with facial recognition can get a bit intensive, plus I wanted to fool around with other services. At the moment, it runs Pi-Hole, Photoprism, Navidrome, and the built-in Video Station (more containers will likely come). If you're into video transcoding and HD/4K streaming, a bit of extra power is likely to be welcome, although I haven't tried Plesk-like solutions just yet. We're not big into video streaming (except for ripping and streaming our De Kampioenen DVDs, of course!).

Again, the pricey hardware might put you off. In that case, by all means, build something custom with spare parts! I only have Athlon CPU processors lying around from the year 2000, so that would be a no-go.

4. How to backup?

Besides the aforementioned services, our NAS primarily acts as an automated Time Machine (and VPS) backup manager. Before, we'd have to manually insert an USB HDD---which we'd forget, meaning no backups at all.

But, as the 3-2-1 backup strategy dictates, what of the backup of the backup? Ideally, that has to be off-site, but since the whole point of this venture is to keep my data local, I didn't like that solution, even if it's encrypted-at-rest somewhere "in the cloud". Besides, uploading terabytes with our cheap ISP is not going to end well. The Synology software is, again, very easy to use when it comes to backups, whether it's cloud or USB-based. For now, a 1 TB USB HDD is responsible for that, and incremental and compressed backups are automatically pushed onto that drive.

Wait, your capacity is 4 TB and your USB backup is 1 TB? Yeah, that's a problem, isn't it? Luckily, selective backups are possible, and I opted to ignore the /music and /video folders. If needed, I could re-rip those: the CDs and DVDs are the third backups. Furthermore, I always exclude folders like /Applications, /private/var/vm, ~/Library/Caches etc from Time Machine backups. In theory, that still doesn't suffice, but we haven't reached the threshold just yet, and I hope the compression technique used will help in prolonging that moment. It currently only uses 118 GB using the Hyper Backup tool.

I could go on, but let's stop here. I think that the Synology systems are not cheap, but are at the right price point, considering the ease-of-use benefit from the software and the excellent build quality and power efficiency. Let's see in the coming months how stable this thing really is.