Unraid: Unleash Your Hardware

This is an automated archive made by the Lemmit Bot.

The original was posted on /r/unraid by /u/TMWNN on 2023-10-01 16:56:48.

BACKGROUND

For some years my home environment has been VMs on VirtualBox on Linux on HP MicroServer Gen7. I've run a very large software RAID array in the past, but it's been 12TB in JBODs on Gen7, mostly because I would have to back up the data, create a RAID array (and lose 25% of capacity), then restore.

I'd risked my data long enough. After obtaining a large-enough external drive I began the long process (whether the drive is plugged into USB 2 on Gen7 or USB 3 on Raspberry Pi via wireless) of backing up the JBODs. I needed to decide what OS to run. My choices:

• Stay with the existing Linux setup, but just create an mdadm software RAID as in the past. Pro: Minimal work needed. Con: I wanted ZFS if possible, but wanted it built into the OS, as opposed to ZoL. Further, I wanted the overall environment to be as self-contained as possible.
• Install VMware ESXi or Proxmox. Pro: Super-sophisticated mature VM setup. Con: Gen7 doesn't have hardware passthrough, and I'd heard horror stories about attempting to run ZFS (or software RAID in general) from a VM via RDM.
• Install TrueNAS (Scale, because I have no experience with BSD). Pro: Self-contained, sophisticated, mature, and with native ZFS support the lack of hardware passthrough would not be a problem. Con: Not much, except the inflexibility of ZFS (or standard mdadm RAID) regarding future expansion. Did I really want to again lock myself into a single-sized array until and unless I build an entirely new, separate one?

UnRAID emerged late in the process. I'd heard of it going back 15 years but had never seriously looked at it. I knew of the flexible RAID expansion ability, but think that said flexibility contributed to my dismissing it in the past because it sounded like a gimmick; after all, if it were so easy to do reliably, surely ZFS and mdadm would have added the ability a long time ago? But the uniformly positive reviews persuaded me to purchase a Basic license.

THOUGHTS

Overall, UnRAID has been excellent.

Pro:

• Ease of use. The UI is simple and straightforward. Having help blurbs available almost everywhere is great.
• The documentation, while not complete, is very detailed yet friendly and approachable.
• The enormous amount of community discussion, both here and at the UnRAID forums. I was impressed by how a) said forums a) go back almost all the way to UnRAID's debut, and b) someone took the time to make sure lime-technology.com/forum/ links still work despite the migration to new forum software. Thoughtful touches like that are evident in many places in UnRAID.
• Being able to search for and install Docker containers and plugins from the UI is great.
• Updates with significant new functionality, such as ZFS. I subscribe to commercial software that hasn't received new functionality (or real bug fixes) in years of anywhere the scale that UnRAID regularly gains.

Con:

• The biggest disappointment is the VM support. I had been happy with VirtualBox, but KVM in UnRAID is a "real Type 1 hypervisor" so had to be better, amirite fellas? Boy, was I shocked when I saw how poor the VM functionality is compared to VirtualBox.

(Yes, I know that UnRAID's GUI does not contain all the functionality virsh has (I've heard that the next major release will improve on this). None of that changes the fact that KVM snapshots don't survive beyond reboots, making it impossible to do what I took for granted when running VMware or VirtualBox: Rebooting the server and expecting that my VMs will gracefully and automatically save, restart, and continue on.)

• As I wrote elsewhere:

Unraids "Cache" has always felt like a joke to me, or a lie. The Unraid "cache" drives are only caches in the most indirect sense. They don't speed up reads, they're not read-ahead or read-behind, or write-through, or like, any of the types of systems that we commonly associate with caches.

Yes. I'm new to UnRAID, but almost immediately noticed its idiosyncratic use of "cache". It should be called "fast storage" or "high-priority storage" something else, not a word that has a specific, well-established definition in computing of short-term, transient storage.

As I understand it TrueNAS uses SSD in the traditional cache sense.

I realize that for the typical UnRAID use case as a media server the TrueNAS cache approach isn't necessarily very helpful. But it would still be preferable in terms of architectural hygiene, if that makes sense, especially given ...

• mover's general ricketyness. Such functionality should in no way be dependent on a userspace shell script, of all things. I keep backups going back years in a homegrown variant of rsnapshot, which means many, many hard links, and mover just gets overwhelmed, running forever and ever. mover also fails to move socket files, causing the directory tree they are in to stay on the cache even if everything else is moved.
• The built-in support for Apple Time Machine, as appearing in the official documentation, is flat-out broken. I did multiple full backups of my MacBook, each time finding that subsequent backups would not work, thinking that I'd done something wrong, erasing the backup, and starting over again. A search for discussions on the topic revealed that it wasn't just me. Thank goodness for mbentley's TimeMachine container, which actually works; as another said, it really, really needs to be adopted as the official method, whether by actual incorporation into UnRAID or at least in the official documentation the way other user-contributed utilities are cited.

CONCLUSION

The above criticisms come in a spirit of wanting a good thing to be even better. I meant what I said about UnRAID's overall high quality. I didn't list the most important pro, the flexible expansion, above because it's the whole raison d'etre for UnRAID in the first place. But to paraphase Seinfeld "it's real, and it's spectacular". I finished moving the data back onto the new UnRAID array last week and almost immediately needed more space. I am in the process of swapping in larger drives, one at a time; knowing in advance that it works in theory is not the same as actually experiencing the seemingly miraculous ability to do so. Still time-consuming, but not as much time (or money for the resulting capacity) as the alternative of again migrating off the array, rebuilding it completely with new disks, then migrating back on. Thank you, UnRAID.