NAS vs DAS vs ?

Intro

A write-up of the 'story so far' when it came to my woes around storage needs. This is the history behind the two videos - to date - what they mean, where they came from - and ultimately where we're going.

Enjoy!

Running out of space

One of the drawbacks of being a major international film producer, coming up with videos that garner literally tens of views, is that it takes up rather a lot of disk space.

My Mac Studio has a 2TB internal drive. Record the footage, edit it, let Final Cut generate all the render files it likes to generate... and that 2TB goes quickly. A couple of weeks before I filmed Part 1, it ran out entirely.

So I looked at what I already had. There is a Synology NAS in the server box with four 4TB drives in it. Sounds like 16TB. It isn't. It runs in RAID 1, so half the space goes on keeping a copy, which leaves 8TB usable and most of that is already busy. Start loading movie assets onto it and I am back where I started by the weekend.

Right. Buy something then. But buy what?

First, work out which problem you have

This is the bit worth slowing down for, because there are three quite different reasons to add storage and they point at three different products.

• You just need more space. The machine is full and you can't easily crack it open and add a disk. A laptop, a Mac Studio, that sort of thing.
• You need it on the network. More than one machine has to reach it, or the telly wants to stream movies off it, or you want it running services.
• You need it to survive a disk dying. If a drive fails you would rather not lose what was on it.

Plenty of people buy for the second when they only have the first. I managed something slightly dafter, but we'll get to that.

DAS: the simple one

Direct attached storage. A disk, in an enclosure, with a cable, plugged into your computer. That's it.

You can buy it off the shelf as a sealed unit, or you can do what I do and keep a couple of bare enclosures around. They're 20 or 30 quid. Drop a spare drive in, cable it up, and it shows up as a disk. For pure speed you want an SSD in there.

Two drawbacks. It's only available to the machine it's plugged into, and a plain single-disk DAS gives you no redundancy at all. One disk. If it dies and you have no backup, that's that.

NAS: the one that's actually a computer

Network attached storage. A disk, or a bunch of disks, sitting on your network and available to everything on it.

The obvious use is media. Your DLNA-compliant NAS serves movies to the television and everyone's happy. But that's barely scratching it. A NAS box will run virtual machines, surveillance software, photo servers, Kubernetes clusters, all sorts. It has its own operating system on internal flash, it has RAM, it has a processor. It is a small computer that happens to hold disks.

Which is the question you need to ask yourself: do you actually need any of that? Because you're paying for it either way.

The Synology problem

I have been a Synology customer for a long time. There's a DS212 knocking about that must be late 2000s, a DS215 from around 2015, and the four bay box doing the real work now, running all our central media and the surveillance cameras.

So when the Mac Studio filled up, my first thought was the easy one. Get a modern two bay DiskStation, sit it next to the machine, done.

Then I remembered they'd gone evil.

It's the usual arc. Company starts small with a genuinely fantastic product, takes investment, and starts looking for ways to squeeze. In Synology's case that meant trying to enforce their own branded drives in the new DiskStations. Which is quite a thing to attempt when you have never been a drive company. Seagate, Western Digital and Toshiba have been designing drives for decades and understand how to do it. Synology were pushing into that market purely because they could lean on being the market leader in enclosures.

To be fair, by the time I recorded Part 1 they'd unwound it, and third party drives work again. Didn't matter. The moment I read about it I was out, and I suspect a lot of long-term customers felt the same.

The rest of the case against doesn't help either. The DS225 I was looking at was north of £300. The technology in it is old. You get a single 2.5 gigabit Ethernet port at best, and Intel processors that Intel themselves no longer sell.

If I do go back to a NAS enclosure, I'll be looking at UGreen. Everything I've seen so far is promising: fast Ethernet, 8 to 16GB of RAM on board, and modern mobile processors. New guy on the market, but they appear to be trying.

What I actually needed

Here's the thing my situation needed that neither answer gives you on its own.

I wanted the redundancy of a RAID array, because losing a project would ruin my week. But I also wanted it attached directly to the computer, because shifting big video files across my network is slow, and USB 3.2 gives me a headline 10 gigabits per second. Far quicker than the network was ever going to be.

So: a multi-bay DAS. RAID in a box, on the end of a cable.

I went with a TerraMaster D2-320. Two bays, USB 3.2, RAID mode set with a physical switch on the back. A hundred quid, against three hundred plus for the Synology I'd been eyeing. Into it went two Seagate IronWolf Pro NAS drives at 16TB each.

Two bays, three choices

With two disks you're picking one of these, and it is a straight trade.

• RAID 0 or JBOD. Both disks in one 32TB volume. Maximum space, maximum speed. Lose one drive and you lose everything.
• RAID 1. 16TB usable. One drive dies, you buy a new one, drop it in, nothing lost.

I went RAID 0. I wanted the 32TB monster.

Part 1 ends badly

I put the drives in, set it to RAID 0, plugged it in, and it beeped at me.

Beeping is not good.

I did the reset dance. Held the button, counted to five. Still beeping. Turns out one of the two brand new drives was faulty. Put it in on its own and the TerraMaster doesn't see it. Put the other one in on its own and it's absolutely fine. Both together, nothing.

A bit of a pain in the plums. Return it, wait for another one, and that's where Part 1 stops.

Part 2: the replacement goes in

New IronWolf Pro arrives, into the caddy, power on, and no beeping. Progress.

Then macOS decided to have an opinion.

Both drives were uninitialized, meaning no file system on them at all. macOS spots that and asks to initialize them, which is what you'd want. Except when you go into Disk Utility and hit erase, you get this:

Erase process has failed. The calling process or user
lacks the proper privileges to perform. Operation failed.

Which is not remotely helpful, and isn't really about privileges. It's a limitation of the Disk Utility interface. The fix is to go around it.

diskutil list
sudo diskutil unmountDisk force /dev/disk6
diskutil eraseDisk APFS TDS1 disk6

Find your disk, force it to unmount, then erase it. I used APFS because this disk is only ever going near a Mac. If it might end up on Windows or Linux, pick exFAT instead. Remember that choice, it comes back to bite me later.

Turning two disks into one

Next, out of JBOD and into RAID 0, so the enclosure stripes the pair together and hands the Mac one 32TB volume.

On the TerraMaster that's a screwdriver job. Flip the switch on the back, then do the reset dance again. It came back almost instantly showing 32TB, which was more graceful than I expected. Erase it the same way as before and it's done.

And it worked. One big quiet drive. I moved three terabytes onto it and sat back feeling pleased.

Speeds were fine, around 500MB/s. You are never going to see the 10 gigabits USB 3.2 promises, that's the interface not the disks, but it's perfectly decent.

Then the two actual problems turned up

Neither of these is really the TerraMaster's fault. Both are mine, and I probably should have seen them coming.

Mechanical drives spin down. macOS tries to be helpful with power saving. It watches whether disks have been used recently and if it reckons they haven't, it parks them. So every time you touch the drive there's a pause while it spins back up. Constant lag on everything.

There's a setting for this. I set it in the UI. I set it in the terminal. I set it to 0 for never, and I set it to 60 for an hour. No change. I spoke to TerraMaster, and there's no firmware on the D2-320 at all, so there is no enclosure-side way to control idle behaviour. It is entirely down to the operating system. Which meant for about a week the thing sat on my desk plugged in and switched off.

They're just not fast enough. Even spinning happily, and they are genuinely quiet, mechanical drives are not quick enough for disk-intensive work. Which video editing very much is.

So I'd solved capacity and redundancy, and made my day-to-day worse.

NVMe, and the new plan

Which brings us to NVMe. Non-Volatile Memory Express, and yes I had to look that up on camera.

It's what most modern machines ship with, usually installed internally on the PCI Express bus, but there is nothing stopping you running one in an external enclosure. So I bought a Crucial T710 4TB Gen 5, about the fastest thing on the market right now, and a UGreen Thunderbolt caddy to put it in. The Mac Studio has Thunderbolt, so the interface can actually keep up with the drive, which matters. A fast disk behind a slow port is just an expensive slow disk.

The plan, then. NVMe becomes the day-to-day editing drive. The TerraMaster stops pretending to be a working disk and becomes long-term storage, hanging off the Synology so it's available across the network. When the NVMe fills up, shift the finished stuff over to it and carry on.

Almost too easy. And at every previous stage something had gone wrong, so...

The filesystem trap

Synology can't read APFS. It wants something like exFAT.

I had formatted the TerraMaster as APFS. And it was full of data. And you cannot change the file system without wiping it.

So the order of operations becomes: move 3.5TB off the TerraMaster, reformat it to exFAT, move the data back, then plug it into the Synology. Which needs somewhere to put 3.5TB in the meantime. Bugger.

The NVMe solved that too, as it happens. Plugged in, initialized first time without a word of complaint, which after the week I'd had felt almost rude. Started the copy. Twenty hours. Nineteen hours.

The bit where I'm an idiot

While that was running I noticed the total wasn't 3.5TB, it was 2.7TB.

Before you archive a Final Cut Pro library you can tell it to delete the render files it generated. I'd done that on a couple of libraries almost without thinking, and it had knocked nearly a terabyte off.

Nearly a terabyte. On a 2TB machine. Which had run out of space.

I am trying not to dwell on the fact that if I had just done that at the very beginning, I could have deferred this entire problem well into the future and saved myself two videos, a hundred quid, a faulty drive and a fortnight.

Live and learn.

Where it landed

For the record, the end state is good, even if the route was daft.

• Crucial T710 NVMe in the UGreen Thunderbolt caddy. The working drive. Everything I'm actively editing lives here.
• TerraMaster D2-320 in RAID 1, formatted exFAT, plugged into the Synology. 16TB of redundant bulk storage, on the network, available to everything.
• The Synology carries on doing what it always did. Media and surveillance.

When the NVMe fills, finished projects go across the network onto the TerraMaster. Fast where I need fast, redundant where I need redundant, and nothing pretending to be both.

Worth saying out loud though, because it would be easy to look at that list and feel sorted. The RAID 1 in there protects me from one disk dying. It does not protect me from me. Delete the wrong folder, or have the enclosure give up entirely, and redundancy shrugs. I have resilience. I do not yet have a backup.

I started Part 1 as a straightforward "here's how to choose between NAS and DAS". I finished Part 2 having learned that there are a lot more options than I made out, and that I'm an idiot. Hopefully me getting it this wrong saves you some of it.

Fittingly, I had to stop recording Part 2 because the SD card in the camera filled up.

What's coming

Two threads left to pull on, and they go in opposite directions.

Part 3 goes back to that cheap enclosure I waved about near the start. There is a solid argument for a budget DAS box that lets you reuse the disks already sitting in a drawer, and that argument gets stronger every month RAM and storage prices climb the way they are. Not every answer has to be a new 16TB drive and a hundred quid of enclosure.

Part 4 goes the other way entirely. If a NAS is really just a small computer with disks in it, and I've now said that twice, then what is actually stopping you building one out of old hardware and some open source software? I want to find out what you give up when you do.

Neither is filmed yet, so no promises on timing. But that's where this is going.

And the thing I've swerved in both videos is still sitting there looking at me. Everything above is redundancy, not backup. Whether that turns into a video or just a quiet weekend of sorting it out, it needs doing.