A modular, extensible DIY NAS

We were running some services on a stack of older Dell servers with mostly identical hardware. The RAID controller and mainboard on one of them let the magic smoke out. We (a sysadmin team of three) promptly decided to move the RAID array to another unused server in the stack in order to avoid a lengthy reinstall and manual restoring of daily backups – this happened before the almost-one-click provisioning of devops and virtualization tools was the norm.

The other server lacked the RAID license dongle that was on a pin header on the mainboard, so we just tried to cannibalize it from the server corpse that barely had stopped smoking. The new mainboard promptly rejected the license because the service tag differed, and the only way to change it was to install Windows 95 or 98 and run the tag changer tool. In addition, we had to downgrade the controller firmware to match that of the old one. One nightlong unattended rebuild later, the server was up and running the next morning.

When we upgraded the server hardware a bit later, we migrated it over to mdraid and haven't had any problems with hardware failures since.

Moral of the story: If you are depending on certain hardware features, you need to have a cold spare available with identical hardware and firmware. If you cannot afford one, it's better to either use a software implementation, have a really good service contract with the vendor or just let a VM provider take care of your infrastructure.

[1] https://davidstephens.uk/ansible-nas/

I’m very surprised you went through the trouble of building such an amazing NAS and skipped ZFS! Definitely give it a try. It’s especially useful for combatting disk rot. Not to mention how easy it is to setup and use.

I went for a Chenbro SR301 case (I don't know what's changed in the still-available SR301 Plus model) + modest commodity parts over the HP or Supermicro turnkey boxes in a similar form-factor mostly because it takes standard components (mini-ITX boards, ATX PSU, standard fans... nothing I couldn't overnight from any major vendor for cheap) for easy replacement. It was also a little cheaper.

I did btrfs "RAID10" instead of RAID. Hardware RAID is always a hassle, btrfs is in-kernel, and it has all the nice modern data integrity features (two spindle rule, I have a timer that scrubs it periodically for to verify checksums, etc.) - I've been really pleased with that except for the lack of good automated monitoring/notification tools for btrfs.

Documentation I wrote at the time, more about the backup scheme than the machine at https://pappp.net/?p=1627 I'm still using that setup, eventually I'll need to swap some discs as capacities increase, but that machine has required zero fucking around since it was set up.

I found it very strange the guy is happy with & measured 100 Mbps throughput over the network. Any 2+ drive NAS from the last 5 years should be able to saturate a 1Gbps link.

RAID6 makes sense for 5-8 drives.

You install it on a USB stick, and the web interface has you up and running within like 2 minutes. The only hard rule is that your parity drives must be as large as or the same size as your data drives, but other than that you’re completely free to add or remove disks one, two, or ten at a time and all it takes is like 3 button clicks.

The community is large so there’s always someone to help should you run into trouble but in general the whole thing is pretty brainless. Click button, server work.

I'm really impressed with how stable it is - never had any issues with it and no dataloss, even with a couple of hard drive failures along the way.

I know many of you will prefer to customise everything and take a deep dive into the way things are set up, but I really do enjoy the simplicity of Unraid.

I would say that a good router is the way to go and I think I should replace the one my ISP has given me. Can anyone point me in the direction for a guide to a hardware router and appropriate firmware, so I can be sure to control what the NAS (or any other device within the network) can connect to on "the internet"?

I always use /dev/disk/by-id/* .

The only somewhat difficult part was preserving data from the old disks as QNAP has custom extensions to LVM or MDRAID which work nowhere else. So there were a few back and forth of removing a few disks from the pool, rebooting to a normal linux, formatting them without the custom garbage, booting back and copying over.

In the end I decided to go with NixOS as I've already used it on my laptop/desktop for about 5 years. I also wanted a modern CoW file system and went with bcachefs. Getting it working with NixOS takes some fiddling, especially if you also want encryption but it works. It now runs samba, matrix-synapse and soon maybe nextcloud. Not quite there yet with everything but quite happy that I went down this route.

The only thing missing from the HW side is an SSD, but the box has USB3 and UAS support so I might add an external one that bcachefs can use as a faster tier.

[1] https://www.qnap.com/quts-hero/en/

Why? Because storing a single copy of your data on a single local RAID array doesn't protect you from disasters such as fire, theft, accidental fluid spills, small children/pets, a power surge after a lightning strike, flooding, and so on. Basically, a lot of the stuff you'd fine in your home insurance policy.

RAID doesn't guarantee data integrity either. You lost data after an unintended deletion or corruption by some computer program? RAID won't help you get your data back any more then a single disk scenario would. If the original file got overwritten and mirrored across the array, and all you had was that one copy, you won't be able to go back to that original.

A more exceptional scenario would be a drive silently failing and RAID happily mirroring corrupted data across the entire array. Unless you use a filesystem that implements checksums - like ZFS - you wouldn't notice this unless it was too late. [1]

[1] https://superuser.com/questions/112683/does-raid-1-protect-a...

I'm not advising against RAID. I think there's merit in using RAID when it comes to convenience and availability. Like, your data remaining available when you experience a sudden disk failure, and not having to spend hours or days getting everything back on line again.

I'd say that RAID and backups are complementary.

So, what about backups then? The 3-2-1 backup strategy is a good start: 3 copies, 2 local, 1 physically remote. That could be as simple as copying your drives every week to a separate HD or SSD drive, and every month to another separate drive which is safely stored outside of your home, i.e. a family member, friend, or at the bank.

You could step it up a notch and choose to rsync your data across two connected drives, while rsync a third copy to specialized cloud storage service such as Borgbackup or Wasabi. Add in scripts that perform regular checksums control and reports the results daily and you've got a pretty solid solution.

The final step is looking at your data and differentiating between the stuff you absolutely can't afford to lose (e.g. family albums) and the stuff you may afford to lose (e.g. software downloads). The goal here is to calculate the costs associated with required storage volume and bandwidth, and land on an appropriate backup solution that matches your budget and your needs.

Finally, that's just safeguarding your data in the present and short term future. Neither RAID or backups are a long term preservation strategy. Which is a whole other can of worms, including such challenges as migrating obsolete data formats (Yeah, I have WordPerfect 5 and AutoCAD files in my own personal archive), or dealing with obsolete hardware I/O (Yeah, I have a bunch of old IDE drives in a cardboard box for which I had to buy an I/O converter).