Expanding Storage on TrueNAS Media Server

TrueNAS General
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What I currently have:

I built a media server using 6x 8TB HDDs (Western Digital Red NAS drives). I also have a “Western Digital 500GB WD Blue SN550 NVMe Internal SSD - Gen3 x4 PCIe 8Gb/s, M.2 2280, 3D NAND” SSD which is the “boot-pool” essentially running the OS. This server is running TrueNAS Core 13.0, and these 6x 8TB drives (which are 48TB total) are raided using RAID-Z1. These disks are part of a pool that we will call “komrad”. This pool has a total capacity of roughly 34.5 TB. I am near full capacity.

What I want to have:

I purchased an additional 2x 8TB HDDs (same as the others, Western Digital Red NAS drives). I want to expand the capacity of this pool by (hopefully) 16TB total. I already connected these drives to the available bays and SATA ports in my server. The new disks are already appearing in the TrueNAS UI, but they are currently not assigned to any pools.

I’m trying to add these to the pool, so I go to Storage > Pool and I click on the option to “Add Vdevs”

On the next page, I attempt to add these two new HDDs to the Data VDevs.

But when I try this, I get the following issues:

“This type of VDEV requires at least 3 disks” and “Caution: Addint data vdevs with differnet numbers of disks is not recommended. First vdev has 6 disks, new vdev has 2.”

Not only does it not let me do it, but it’s saying I would only get ~8TB out of it (rather than my expected or hoped for 16 TB).

What should I do to expand my storage? I suppose the worst case scenario is I would have to destroy the pool completely and re-build it and re-create the raid-z1 using 8x 8TB from scratch. However, to do that I would have to lose all my data, and to avoid that, I would have to somehow be able to back up like 34TB of data. Is this my only option? If so, how would you recommend I find a 34+TB backup storage solution?

Is there anything else I can do to expand my storage here? Is creating a new and entirely separate pool the only other thing I can do? If I do that, would I be able to set up a way to continue adding to my data in the “komrad” pool and have it spill over to the new pool once “komrad” is full?

How would I be able to expand my Z1 with one drive at a time, is there a way to do that?

What are all my options? What should I do?

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You can’t with TrueNAS Core.

RAIDZ expansion is only available on SCALE (that ships with OpenZFS 2.3.x), and will never be available with Core.

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You have a few problems. Raid-Z1 with large drives isn’t recommended due to rebuild risk and time when a drive fails and you don’t seem to have a backup of your current data.

Upgrading to Scale is currently has you doing a few upgrades for Scale or a clean install of the latest Scale version per the Documents. Fangtooth Scale, to be released later this year, is supposed to be a direct upgrade path.

“TrueNAS users wanting to migrate from 13.0-U6 (latest) or 13.3 to TrueNAS 24.10 or later can migrate to 24.04 and earlier using the UI, but must clean install if migrating to later releases. Attempting to migrate directly to 24.10 or later releases fail and cannot be done.”

Post your detailed hardware and software setup so we can make informed suggestions.

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So, you can use RaidZ Expansion in Electric Eel and beyond to do what you want.

There are some caveats, the biggest being that space reporting is wonky afterwards.

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So does that mean I should probably upgrade to TrueNAS Scale then? I’m currently running an Emby jail on my server and I think (it’s been a few years) I recall reading that only Core supports jails and Scale does not? Or rather, perhaps Scale uses another system?

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Well, in my OP I already mention what kind of storage devices I have. My cpu is a Ryzen 5 and the primary purpose of this media server is to provide backup storage to my personal PC, but also run an Emby server on a jail to access my media over the internet.

It’s currently on TrueNAS-13.0-U6.4

So, do you recommend I wait until Fangtooth releases to upgrade (do you know exactly when that will be?) or can I just go ahead with the current version?

What other details do you want that I have not yet included in this post or in the OP?

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What is “Electric Eel”? Is that the name of the current latest version of TrueNAS Scale?

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It is the name for TrueNAS Scale 24.10 (The “E” release that was released in October 2024)

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I would look at the forums for Fangtooth version that is upcoming. Listing of Scale versions below. Fangtooth will have LXC, which is like jails. You have to research your Emby to see how it would be set up to run under Eel or Fangtooth. If you have a spare computer or wish to play with it in a VM, you can look at the nightly of Fangtooth. Just for testing.

Knowing your hardware details would help us know whether you have a SAS HBA and can attach a lot more drives or if you are out of SATA connections. Your other expansion of pool space option is replacing your current 6 drives with larger models, one at a time, six times until they are big. Problem is you are keeping Raidz1 and have made drive recovery even worse with larger units.

Another option is buying four of largest drives, like 22TB, and creating a RaidZ2 pool and transferring the data.

25.04 Fangtooth - guessing April?
24.10 Electric Eel - current
24.04 Dragonfish - previous

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Why do you think RAIDZ2 better than RAIDZ1? Also, with regards to switching over to TrueNAS Scale ElectricEel, would the best way do to that be via the browser GUI? I can log into my machine via browser, go to System > Update and from the dropdown menu select TrueNAS Scale ElectricEel 24.10 [release] and follow the steps there?

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Raid-Z1 VDEVs with large drives are at risk of the pool dying if it loses a single drive and also during the resilver process when you replace the failed drive with a new one. That would mean losing all your data. You would have to have a complete backup of the data to rebuild and recover your pools.

Raid-Z2 gives you two drives of redundancy so it is less risky when you have replaced a single failed drive and while the system is doing the resilver. The issue is you are using two of your four drives for redundancy so you only get half of your raw capacity. It is the same as having two mirrored vdev pairs of two drives

Currently, upgrading from Core to scale you have two options.
GUI updating Core to Dragonfish Scale (24.04) then to Electric Eel (24.10)
or
Core with a completely new install to Electric Eel (24.10) You have to use a USB with the ISO written to it to boot and install. You should be able to import your pools but you would have to set up shares, networking, etc. Apps and Jails would need to be recreated from scratch under the equivelent in Electric Eel (24.10)

primers on ZFS and pool layout
BASICS

iX Systems pool layout whitepaper

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@SmallBarky @Stux Okay, I’ve successfully upgraded my server to TrueNAS Scale ElectricEel 24.10. What is the process now for expanding my disk storage?

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Documentation section for your version. Make sure to expand and read some of the hidden sections before you start.

@Stux Can you only add one disk at a time or can two more disks be added and then the Raid-Z expansion can be called / activated?

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One disk at a time. I know, I had to go through 4 sequential expansions.

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Thanks. I was able to expand my pool adding the two new drives one at a time (it took roughly 6 days to complete this process). So now I’m at about 48TB of total usable capacity (up from like 36TB) with my 8 x 8TB setup in RAIDZ1. I’m primarily using my TrueNAS as a media streaming server (with its secondary function being a backup storage for my main desktop PC). In the future if I want to expand the drives or maybe replace each one with a larger one wouldn’t using RAIDZ2 (like you suggested) eat up even more of my usable drive storage space?

In general for the application I told you, what would you say would be the best RAID type? You still think RAIDZ2?

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Raid-Z2 would eat up one more disk for redundancy but is recommended due to the Raid-Z1 being venerable to a total pool loss if a single drive dies and if the replacement drive and resilver don’t happen.

If you have backups of all the data or it is considered easy to replace the data, Raid-Z1 and max capacity is fine. For example, you can download Linux ISOs if you lost them to a pool failure. It is a trade off you would have to accept.

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