UnRAID Revisited with the LincStation N1

 

Tested Technology is approaching 2024 somewhat cautiously and frankly with little sign of optimism from a socio-political global perspective. But let’s look on the bright side. UnRAID is back!

Regular readers may remember that in 2020 we published a series about our adventures with the UnRAID NAS system, running on an out-of-warranty 8-bay QNAP server. The hardware held together just long enough for our 5-part series but in the early months of 2021 its soldered-in processor failed. QNAP couldn’t repair it and we were left with a bunch of drives but no UnRAID system to run them on.

If you’re going to have a massive hardware failure like this, UnRAID is probably the best NAS operating system for it to happen to. Unlike the RAID systems that QNAP depends on, UnRAID allows you to decide what data goes on what drives. It puts the files where you say you want them and optionally guards over them all with one or two dedicated “parity drives” that provide redundancy in the event of drive failure.

This design very much enhances the chance of easy data recovery not just when a drive fails but also when the entire NAS unit conks out. So when we heard about UnRAID’s new tie-in with the German hardware manufacturer LincPlus, we saw a chance to get back into the UnRAID adventure at a price that Tested Technology could just about afford.


Towards the end of 2023, LincPlus was pitching a small all-solid-state NAS on the crowd-funding site Indigogo. That campaign is now closed, as is the original offer price of £259. A second production run is scheduled for mid-March of this year, at the new price of £388.

The original price represented something of a bargain for a 6-bay NAS. The new price is still very much less than you have to pay for a typical 6-bay NAS like the £600 Terramaster T6-423. It buys you the hardware (without drives) and also includes a basic UnRAID licence, which would otherwise knock you back £47. The basic licence covers a single server running a maximum of six drives. The LincStation N1 can take more drives, however, using USB 3 expansion. If you want to add extra drives you can always extend the licence to cover up to a dozen drives for an additional £30.

Is UnRAID a Good Fit?

The headline announcement has to be No, it’s not! The LincStation N1 and the current version of UnRAID is not a marriage made in heaven. The mismatch isn’t a showstopper but it definitely gives pause for thought.

As a low-cost NAS device aimed at home and small office users, the LincStation N1 needs an operating system. Synology, QNAP and Terramaster know that manufacturing clever hardware is only half the solution and offer operating software designed in-house to match their hardware. LincPlus has not been developing its own software. Instead it has created a generic, Intel-based NAS capable of running a variety of NAS operating systems and bundled with a basic licence for UnRAID.

WiFi has never been a core component of NAS technology. In the past, wired Ethernet connections have been the preferred data transfer method for storage devices designed to serve data over the network simultaneously to multiple users. But the LIncStation N1 is small, light and portable, a NAS equally at home in a backpack as in the cupboard under the stairs or on a studio shelf. It makes complete sense that the N1 should offer WiFi and UnRAID’s current lack of support for this is a distinct shortcoming.
But this hardware doesn’t quite fit the operating system. The LincStation N1 has a couple of wireless features that traditionally the core of UnRAID has ignored. The NAS offers Bluetooth and WiFi connectivity. WiFi might be a great way of getting a notebook like our Framework laptop onto the LAN without having to fuss with wires, but a wireless connection isn’t optimal for a NAS. However, the N1 is small, light and portable and you might well want to hook up with it on the fly without messing with Ethernet cable. Tough. UnRAID says “no thanks”.

Additionally, a predominant cosmetic feature of the N1 is that strip of multi-coloured LEDs in the space below the flip-down SATA drive cover. On powering up for the first time this gives a brief Aurora Borealis effect, thereafter settling down to a persistent slowly pulsing blue glow. Clearly this hardware feature is overkill for the information it currently conveys: “Hello, World” and “I’m running”.

An operating system specifically designed for the hardware would want to do more than this: with different colours for “array running” and “array stopped”, perhaps. And quickly flashing red, for example, to signal an error condition. (We did test this by pulling a USB drive on the L1 we were temporarily sharing across the LAN, but the calm blue pulsing continued.)

The N1 has its own come-back, rejecting some important features of the bundled operating system. UnRAID’s unique approach to network attached storage offers an attractive alternative to conventional RAID, as we discussed here. But there’s a catch. Originally developed from a hobby project in the late 1990s, UnRAID has always focussed on hard drives, rotating disk storage—or, as the industry affectionately calls it—”spinning rust”.

The inclusion of solid state drives in UnRAID has been a very recent development, and their use in the classic UnRAID array still has some serious limitations.

Each column represents a bit of data written to the drive. The parity drive records a zero or a one depending on whether the total number of ones in the row is even or odd. Zero ones counts as even.

The parity drive or pair of drives (let’s call this the parity check mechanism) is watching over each and every drive in the active UnRAID array.

Maintaining parity for traditional UnRAID involves checking the state of each bit newly written to the main array and writing a corresponding bit to the parity check mechanism. So each UnRAID write to the array requires a second (and possibly third) write to the parity checker.

Solid state drives aren’t ideal guardians of parity in situations like this. While new information written to a hard drive can simply overwrite outdated information already on the drive, SSDs can’t do this. Before an SSD can store new information over old, even if it’s only to change a single byte, it has to operate a “scorched earth” strategy that clears the way by sending a high negative voltage into an entire block of storage space (which might be as large as 512KB) to wipe it clean. (The requirement to store all that information temporarily somewhere else before the erase further complicates the process.)

TRIM“—in this context typically spelt using all caps— looks as if it might be an acronyn. It isn’t. It literally means “trimming the SSD”, an automatic process that maintains the performance of the storage device by deleting invalid information and making space available for new information. TRIM kicks in periodically to help the SSD perform better and last longer.
Writes and erases like this have to be managed judiciously, as each operation to some degree diminishes the capacity of the medium to retain data. So SSD controllers have an important task that traditional hard drives don’t need to carry out. “Wear leveling” spreads out writes across the SSD memory so no one area wears out prematurely. Another process, TRIM, run by the operating system, kicks in from time to time to erase areas of stale data in preparation for new writes.

The current version of UnRAID (at the time of writing, version 6.12.6) doesn’t support TRIM on the main array. Without it, the parity checking role accelerates wear. 

For this reason, Lime Technology doesn’t recommend using solid state drives for the primary UnRAID array. They’re planning a fix for an upcoming release. But we understand that TRIM on primary UnRAID arrays using SSDs will be limited to a maximum of two devices, still an important restriction. 

So we won’t be running an UnRAID array on the LincStation N1?

But hold on a moment… There’s more to it than just the array. Although UnRAID originally centered on the idea of a bunch of independently functioning storage devices watched over by a single parity check mechanism, in January of 2015 Lime Technologies introduced the concept of “Unassigned Devices”. This allowed the operating system to acknowledge the presence of devices within the NAS but outside the main array. A year later, the UnRAID community made this feature usefully available with the “Unassigned Devices plugin”, providing an easy way to share unassigned devices across the LAN.

This development meant that an UnRAID NAS could optionally run as a JBOD (just a bunch of drives) server. Alternatively, multiple storage devices could be combined into a conventional Linux storage pool and be run outside the UnRAID array as an unassigned virtual device. This would include sophisticated Linux storage pool configurations using BTRFS (introduced into UnRAID in 2015) and ZFS (2023).

These storage pools have provision for their own methods of redundancy, so running them as unassigned devices needn’t risk data loss. Now information can be stored in unassigned devices no less safely than inside the main UnRAID array.

It would be true to say that recent UnRAID development has made the foundational concept of UnRAID, er, redundant.


**Slackware is being super-cautious here: technically, major version 5 is the latest “stable” version suitable for production environments. However, major version 6 has been widely relied on by users and industry for the past couple of years.
UnRAID is based on Slackware, an ancient Linux distribution still actively maintained, although with no particular sense of urgency—its current Linux kernel is a major version behind most other current distributions**. But this is something Lime Technology has fixed and UnRAID currently uses kernel major version 6 like most other modern Linux distros. 

However, the current 6.12.6 version of UnRAID won’t work without the implementation of a primary UnRAID array. So here’s the paradox: to run UnRAID on all-SSD hardware like the LincStation N1, you must have an original-style UnRAID array. This kind of array isn’t currently isn’t recommended on all-SSD hardware, due to the lack of TRIM support.

UnRAID on a Solid State System

The donation of the LincStation N1 was managed by Lime Technology’s Marketing Manager, Spencer Jones, who also helped with some early suggestions about tailoring the UnRAID installation. At first these ideas seemed to incorporate their own paradox.

The simplest option, Spencer suggests, is to go ahead and use the two SSD SATA drives as a regular UnRAID main array. Spencer says: “There may be minor degradation due to the current lack of TRIM support, but it will be resolved in an upcoming release.”

At the time of writing there’s no official date for this upcoming release, and so no time limit to the possible degradation. Spencer’s alternative suggestion was only very slightly more complicated.

Some little-used features of UnRAID give us wiggle room here. Firstly, you can have a perfectly viable UnRAID main array without protecting it with a parity drive. And despite its name, your array can be just a single drive. What’s more, the array doesn’t even have to be running—you can use your unassigned drives, and, indeed, many of the UnRAID features, with the main array powered down.

So we followed Spencer’s radical second suggestion while awaiting the upcoming release of the next UnRAID version. The idea is to create a dummy UnRAID main array and leave it idle. This is absurdly easy to do cheaply: just insert any old small capacity USB stick into one of the N1’s USB sockets, set this up as an unprotected, single drive main array, and never run it up.

This is in anticipation of a promised future version of UnRAID (not the upcoming release that introduces TRIM to the solid state main array) that will allow the UnRAID system to run entirely on unassigned drives, with no requirement for the traditional UnRAID main array.

So in what sense, we’re left wondering, will this continue to be UnRAID?

The UnRAIDing of UnRAID

This means that although initially designed for hard drives, UnRAID can run on an all-SSD setup by taking advantage of the unassigned drives feature. We tested this with our initial very basic installation, using a single 2GB USB stick in one of the L1’s two rear USB sockets, as a powered-down non-parity-protected main array. The only other data storage in the L1 at this point was a 2TB SSD in the left-hand 2.5″ drive bay.

Image description Individual apps like this one from maintainer dlandon of Georgetown, Texas tend to have their own UnRAID support forum

We installed two apps on this system, starting with the Community Applications app. This in turn allowed us to install the Unassigned Devices app, which makes it easier to manage storage not included in the main array.

One of the defining features of UnRAID is that it stores its entire system on a USB stick. This distinguishes it from NAS systems like Terramaster’s TOS 5, which have the boot loader on USB but run the system from the hard drive.

UnRAID boots from the USB stick but then the whole system is transferred across to a virtual disk drive. As this is created in RAM it’s very fast.

Simple plugins like the two we’ve installed are also stored in the USB boot drive in the /boot/config/plugins directory. The internal 4GB boot USB supplied with the L1 comes with the operating system ready to run and leaves about 3.5GB of free space on the USB. This is plenty for plugins, that tend to be only a few kilobytes in size.

This is our initial test configuration. With the main array—the 2GB USB stick—permanently idle and the 2TB SATA SSD we had originally used as cache in our first UnRAID series now serving as an unassigned network share, we’re starting with what is probably the simplest possible NAS setup while we wait for the upcoming UnRAID developments from Lime Technology.

The current version of the UnRAID operating system requires the main array to be running before you can install dockers. Although the design intention is clearly that the dockers be installed on the main array, it should be possible to edit the individual docker install configs to place the installation elsewhere. We’ll be testing this in part 2.
We have a couple of Seagate-donated 2TB NVMe drives standing by for our next hardware expansion and we’re looking forward to installing more of the Community Applications. The catch here is that many of these are docker-based apps or are built on virtual machines. These will be pre-configured to install on the main UnRAID array, which in our case we have not got. Happily, Community Applications present their default configurations prior to installation, so directing the installation to the SATA SSD should be a simple text edit.

It may well be that the next version of UnRAID, providing TRIM for the main array, will have arrived in time for part two of this story. As mentioned, it’s our understanding that TRIM will only be applicable to two-drive SSD arrays. This would be a serious restriction because a two-drive array consisting of a data drive and a parity drive is the exact equivalent of a RAID 1 array, which simply mirrors the data across the two drives. A large part of the appeal of UnRAID lies in the economy of using a single parity mechanism to watch over an array of multiple drives. Efficiently saving storage space becomes an important consideration when you’re employing SSDs.

Not a Conclusion

We’d initially thought our adventure with the LincStation N1 would be picking up from our original UnRAID story from two years ago. But this is turning out to be a whole new ball-park. We’re privy to an inflection point for UnRAID as it remodels itself to accommodate a new kind of storage that’s evidently destined to become ubiquitous.

While Lime Technology’s UnRAID developers work on the general fundamentals—TRIM support and the ability to opt out of a conventional spinning rust UnRAID main array—it will fall to the UnRAID community (or, less probably, to LincPlus) to exploit any specifically N1 refinements like WiFi and the possibilities of the pulsing frontal colour strip. The extent to which those N1 features might be developed, of course, will depend on uptake of the product by UnRAID users.

And here there are no guarantees. But even if we get no further than the hypnotically pulsing blue colour strip and if its WiFi is doomed to lie fallow, the all-solid-state LincStation N1 is a valuable challenge to Lime Technology’s developers and is likely to remain a handy option for UnRAID users.


Chris Bidmead

 

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