External SSD not visible for backups after reconnection to Nucleus+ (ref#CFT2M4)

Support
1

Hi! What’s not quite right with Roon?

· None of the above quite fits

None of the above quite fits

· None of these quite match

Tell us what's going on

· After disconnecting and reconnecting the external SSD (used to perform database backups) to my Nucleus+, the external disc is no longer visible in the “backup now” section of the Roon app on my iPad

Tell us about your home network

· Nucleus+ connected with RG45 cable to home network

2

Did you disconnect the disk while the Nucleus was running or did you shut down the Nucleus before unplugging the disk?

And which file system format does the disk have?

3

If the drive was not unmounted properly it may need to be “repaired” before it is seen again.
Try connecting it to your PC/MAC and scanning the disk for errors and repair them, then properly eject the disk from the PC/MAC and try it again on the Nucleus+.

You may also want to check what format the disk is, as the recommended format is exFat or ext4 for compatibility.

4

Just to add to @bearFNF excellent suggestion, it doesn’t matter if the drive repair utility reports no errors it still will “reset” the drive ready to use again so don’t be despondent if it says no error found.

5

The Nucleus was running at all times

6

Meaning that the disk wasn’t cleanly removed, i.e. the operating system didn’t have a chance to sync all in-memory data to disk.

Other operating systems give you the option in the UI, e.g. the „Safely remove hardware“ task bar button in Windows or the unmount option in the Mac Finder, but the Nucleus doesn’t, and you should shut it down before yanking disks.

Different file system formats are sensitive to this in different degrees. Hence why I asked what your disk uses.

The Windows NTFS format doesn’t like it at all and the disk is always automatically flagged as dirty, requiring a disk check in Windows. Without such a check, Nucleus won’t mount it again because it can’t guarantee its integrity.

7

I use the external SSD only for Roon database backup. Does that apply to my case too?

8

It would make it more compatible and reliable if it used one of the recommended formats.
Especially if you are relying on it for back-up of your database.

NTFS has shown issues in the past on the forum with the Linux.

9

Hi @Ant_Wos,

Thanks for writing in and for sharing your report!

A fresh Nucleus diagnostic report shows us the issue clearly - the external SSD is a WD Elements SE 500GB, and critically it’s formatted FAT (likely FAT32), not exFAT or ext4:

  • FAT-fs (sda1): utf8 is not a recommended IO charset for FAT filesystems
At disconnect, the OS had unflushed data in memory:
  • usb 2-4: USB disconnect → immediately followed by blk_update_request: I/O error, dev sda, sector 2048 op (WRITE) ... lost async page write
That "lost async page write" is the answer. The drive was pulled while the Nucleus still had a pending write to the partition's boot sector/FAT area, so the filesystem was left in an inconsistent (dirty) state. On reconnection the Roon Server can't cleanly mount it, so it doesn't appear as a backup target. @bearFNF, @Suedkiez, @AceRimmer) diagnosed this correctly.

Proper next steps for you:

  • Repair the filesystem on a PC/Mac. Connect the SSD to a computer and run a disk check, chkdsk X: /f on Windows, or Disk Utility → First Aid on Mac. Even if it reports no errors, this clears the dirty flag so Roon Server will mount it. Then safely eject before unplugging.
  • Reconnect to the Nucleus+ and re-check "Backup Now." It should reappear once the dirty flag is cleared.
  • Reformat to exFAT (recommended) going forward. Since the disk is only used for backups, reformatting to exFAT avoids the FAT charset warning and is far more tolerant of the Nucleus' lack of a safe-eject button than NTFS. Back up any existing backup files first.
  • Always shut down the Nucleus+ before unplugging the disk in future, the Nucleus has no "safely remove" option, so a clean shutdown is the only way to guarantee writes are flushed.
Hope this helps! 👍