Error: Topology. Assigning a second disk to existing pool error

TrueNAS General
1

Error: topology

Disks have duplicate serial numbers: None (sda, sdb).

Hello, Truenas community. I’m a brand new homelabber with my father, after getting him a Direct Attached Storage enclosure and a mini PC. We Frankensteined a homelab server together.

The DAS is a 4 Bay enclosure that attaches to the server via a USB-C connection (sigh), this is basically a JOBD on the network. My father is supplying the jellyfin content and I’m spearheading the tech aspect of this op. We arnt that concerned with redundancy and we have backups elsewhere. anywho, after scrolling for a fair bit I’ve only found solutions for VM instances of Truenas. I’m posting to see if anyone has any solutions for this situation.

Issue recreation

  1. Created a main pool with a 7TB WD HDD. Server is going well with jellyfin and such, SMB too.
  2. upon trying to add the 3TB WD HDD, this error appears.

As mentioned before, the drives reside in a DAS enclosure that interfaces via USB-C.

System Stats

Server (Computer)

OptiPlex 3060

Truenas CE 25.10.1 - Goldeye

Intel(R) Core™ i3-8100T CPU @ 3.10GHz 6MB Cache 4C/4T

16GB DDR4 memory; 256GB M.2 NVMe SSD

Integrated Intel UHD Graphics 630

“unknown ssd name, 193687804806” 238.47GB SSD (Root, Boot)

sdb WD-WMC4N0F66JZV 2.73TB

sda WD-RD2XEL3H 7.28TB

Direct Attached Storage enclosure

QNAP TR-004 4 Bay USB Type-C Direct Attached Storage (DAS) with hardware RAID

Hard Disk Interface: Serial ATA

Hardware Connectivity: USB 3.0

Truenas Shell

bash: lsblk -f

sda

└─sda1 zfs_member 5000 PoolMain 5232796613009461571

sdb

└─sdb1 ext4 1.0 DAS2(3TB) 1235bb0c-f809-4930-9c2d-d794681d4340

nvme0n1

├─nvme0n1p1

├─nvme0n1p2 vfat FAT32 EFI 58C7-B6BA

└─nvme0n1p3 zfs_member 5000 boot-pool 14663386175945677

ls /dev/disk/by-id

ata-WDC_WD30EFRX-68EUZN0_WD-WMC4N0F66JZV

ata-WDC_WD80EAAZ-00BXBB0_WD-RD2XEL3H

usb-QNAP_TR-004_DISK00_51595642323032353037-0:0

nvme-WDC_PC_SN730_SDBQNTY-256G-1001_193687804806_1 usb-QNAP_TR-004_DISK01_51595642323032353037-0:1

(there were lines that were omitted since copy and pasting from truenas shell is unsupported. I copied from inspect element tediously.)

I’m a homelab rookie, i tried to look around the best I could but it seems USB is the worst type of connection for this setup. Making this expensive ass DAS enclosure a waste of money. Whats next for me here yall?

2

So that enclosure has its own raid controller. The config software for that is only available for Windows or Mac, but there should be DIP switches to change the configuration.
You could try jbod and see if both disks are passed through with serial numbers, and create two pools with one disk each.

That would lead to the highly unrecommended and advised against configuration of a) single disk pools with no redundancy b) a usb connected enclosure with c) a raid controller (instead of zfs mirrors/raidz).

You could use the two disk to create a mirror, but it would only use 3TB of the larger disk.

I guess you could also stripe the disks together as two vdevs, but that would be even worse, you’d loose all data if one of the disks fails.

Really truenas is not made for this type of hardware, you’d want at least two disk of similar size, connected individually to a hba or onboard sata and configured as a mirror.
Maybe omv or unraid could make better use of the hardware you have right now.

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3

Thank you for the suggestions. it is very true that jbod with stripe is straight up stupid, but redundancy is something me and my dad talked about, we got several stable backups elsewhere. the purpose of this truenas is to facilitate our decade running movie collection via jellyfin.

I’ll take a look at the hardware raid, and with any luck we’ll be able to get just RAID0. I’ll post my findings

4

Just re-read the original post, is truenas virtualized, too?

Using the inbuilt hardware raid was not what I meant, that will likely make matter worse.

The DAS has a single disk feature, I guess that means combining different drives and presenting it as one drive, likely with one serial. That might trick truenas into thinking there is just one usb drive attached with 10TB. Use that to create a single disk usb pool. This might work, but it is not a good solution.

Also, did you create a separate vdev for the second drive before striping it to the existing pool?

5

Our server is not virtualized. We were unable to add the second drive as a vdev because of the Missing serial error. we talked about your suggestion and that is the best way to go. however we figured that adding a significantly older 3TB drive into the pool was a risk too signficant in general. (even tho we’re still being risky, idk). either way we’re looking to upgrade the bay with another 8TB WD. and then ill update later down the line.

Edit: There is a “individual mode” on the DAS. but there is also a JBOD and raid configs. The plan is to use JBOD with 2 similar drives (age speed capacity). HDDs that size are a chunk of change so its gonna be a bit LOL

Off topic question, do posts on this forum necrotizen/auto archive after inactivity in the thread? i wanna keep this thread updated to help people possiblely but idk how long down the line it’ll be till we grab another drive.

6

Okay, missing serial is likely, maybe related to this, if you have not found the thread yourself.

In the end it depends how the usb enclosure presents the drives.

Threads are not closed automaticalla afaik.

7

That’s the one you want to use, it should (hopefully) pass each disk through as an individual device, complete with independent serial numbers.

And threads don’t archive or auto-close here. :slight_smile:

1 Like