Failed Roon backup on Nucleus using exFAT thumb drive (ref#35CAKJ)

[Mark_Sealey]

What’s happening?

· Other

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Describe the issue

Where are the Roon logs (macOS 15.4.1) to help me diagnose a failed Roon backup, please?

Until ten days or so ago I was always able to make a successful backup of my Roon database on Titan from the Roon Backup screen using a 64GB (Patriot) thumb drive exFAT format.

When that failed, I bought a 128GB SanDisk drive, formatted it (again as ExFat). But I have only been able to run the backup once. Now it again fails with the attached screengrab - despite a restart of the server; and despite re-seating the thumb drive using a short extension (male to female) cable into my Nucleus.

Now neither the new Volume nor Device appears to mount at the filesystem level - as if (I will be wrong here, I'm sure) the very attempt to run the backup has somehow corrupted the thumb drive!

Everything else - including all APFS format backups - always work faultlessly on my Roon setup.

Thanks in advance… :-)

Describe your network setup

Nucleus Titan USB to external thumb drive

[vadim]

Hello @Mark_Sealey,

Thank you for reaching out to Roon Support.

Based on the diagnostic data we’ve collected from your account, it appears that the RoonBackups folder is currently mounted as a network share, rather than as a directly connected USB storage device on your Nucleus Titan.

192.168.0.170/RoonBackups on /roon/sys/storage/smbmounts/RoonStorage_d5885a631788396bd6979968715fc814c9e1ecf9 type cifs (...)

However, this network host appears to be unreachable or the mount point no longer exists:

df: /roon/sys/storage/smbmounts/RoonStorage_d5885a631788396bd6979968715fc814c9e1ecf9: Host is down

Could you please clarify whether your USB drive is physically connected to the Nucleus, or if it is connected to another device on your network? This information will help us guide you through the correct configuration for your backup location.

Looking forward to your response.

[Mark_Sealey]

Thanks, @vadim; I have two backup routines.

Yes, I do have a backup path on a permanently-connected Samba share to my iMac. That always works.

It’s on the USB Thumb drives which backups have started to fail - with two different USB Thumb drives:

64 GB Patriot
128 GB Sandisk.

Each has been temporarily mounted (then subsequently unmounted - which will be why your view into my diagnostics - THANK YOU! - reveal it as unreachable) via a short Male to Female USB extension cable directly from my Nucleus. The first one worked from the time I bought my Nucleus until about ten days ago.

I then bought the second (larger) thumb drive, on which the backup worked only once. It too now fails.

Each has been formatted using Apple’s Disk Utility to exFAT; and after a failed backup as described (the Roon backup process reaches the end of the 'Transferring x%); then fails), will no longer appear in either filesystem.

[Rugby (aka Daniel or Big Dan)]

Hi Mark,

Fellow user here.

Have you tried plugging the USB key directly into the Nucleus USB port? That would help test the possibility that the USB extension cable might be faulty.

-Daniel

[Mark_Sealey]

Thanks, @Rugby; Yes - that would certainly eliminate at least one possibility, wouldn’t it.

The Titan has two USB ports; I have tried both USB drives in each port. And would point out that I also shut down the Roon server from the web interface each and every time before experimenting with swapping the thumb drives around… no hot swapping IOW.

In the hope that it helps, @vadim, please let me know what the logs say and/or view yourself for two more fails between 10:53 and 11:00 PDT today (that’s just before 6 PM UTC).

May I also add that I have just (13:28 PDT or 8:28 PM UTC) run the latest SMB Roon backup to my iMac, as usual, which completed - as it always does - without error:

[benjamin]

Hey @Mark_Sealey,

Thanks for the additional information and insight! We were able to locate the failure in your Nucleus logs and saw the following error:

Warn: [backup] failed to sync: putfile hash: AttachedDir:/roon/sys/storage/mounts/TitanBackup_SanDisk_3_2_Gen_1_5B4C0AB0D882_6811-3197-p1/RoonBackups/cac1a178-32b7-4179-8afc-eebac8758421/ab/e3/abe3fb26bccb91bf0cdef2a44b6e8a2787c7d22980cc6fe0ffb551861b3962b3: Result[Status=UnexpectedError, ErrorText=System.IO.IOException: Input/output error : '/roon/sys/storage/mounts/TitanBackup_SanDisk_3_2_Gen_1_5B4C0AB0D882_6811-3197-p1/RoonBackups/cac1a178-32b7-4179-8afc-eebac8758421/ab/e3/.tmp-abe3fb26bccb91bf0cdef2a44b6e8a2787c7d22980cc6fe0ffb551861b3962b3'
   at Interop.ThrowExceptionForIoErrno(ErrorInfo errorInfo, String path, Boolean isDirectory, Func`2 errorRewriter)

It appears that Roon was attempting to write a file (PutFile) during the backup process but encountered a low-level filesystem error. This could indicate a few potential areas of issue:

1. Hardware-level issues with the drive: the drive may be experiencing hardware degradation or temporary failure, like overheating, failing, or losing power intermittently. Since you mention this is a new drive, it would be surprising if this was the case.
2. Filesystem corruption: the target filesystem (exFAT) may be corrupted, preventing safe write operations. Again, this would seem odd since you were able to successfully perform a backup recently.

@Mark_Sealey

The Titan has two USB ports; I have tried both USB drives in each port.

We’re seeing the same failure for the Patriot drive as well, and since you’ve already tested both across both USB ports, this is telling that the issue is not isolated to the drive or the specific port.

As a first step, perhaps accessing the webUI and performing a RoonOS reinsatll may be helpful here - let me know if you’re able to perform this and test another backup.

Did you format both drives the same way? Completely separate of Roon and the Nucleus, would you be able to test the drive on another computer for signs of hardware issues?

Running disk diagnostics certainly wouldn’t hurt as well - On macOS: use Disk Utility > First Aid. I’m wondering if there’s an odd failure occurring from the drive format process from Apple’s Disk Ultility.

One other thing to try would be reformatting one of the drives to EXT4 if you’re comfortable doing that. I’d be curious to see if you run into the same failures.

[Mark_Sealey]

@benjamin

@benjamin

…We were able to locate the failure in your Nucleus logs and saw the following error…

Many thanks for your quick and helpful reply!

May I respond to the possibilities which you kindly suggest as causes as follows:

I agree that it’s extremely unlikely (though always possible) that each of the two external USB Thumb drives in question has failed. Especially since the 128 GB was of a high quality, new and did work once.

…this is telling that the issue is not isolated to the drive or the specific port…

Nor - I would have thought (and please do correct me if my assumption is faulty - that the Roon database is corrupt: it backs up perfectly every time over the SMB share to my iMac.

I know that exFAT is not the most reliable of formats.

Particularly under these circumstances: from the Nucleus via USB.

And - perhaps even more relevant - when it was formatted using Apple Disk Utility.

As a first step, perhaps accessing the webUI and performing a RoonOS reinsatll may be helpful here - let me know if you’re able to perform this and test another backup.

I’m a little nervous doing this, wanting to leave well alone on my Nucleus - particularly since it’s that same RoonOS which works so well every time when running a Backup (from Roon, of course) to my APFS volume.

== Now to what seems to me like the most telling factor ==

Did you format both drives the same way? Completely separate of Roon and the Nucleus

As far as I can remember the 64 GB Patriot, Yes: it arose from this thread when I first got my first Nucleus at the end of 2023.

The recent 128 GB Sandisk definitely.

would you be able to test the drive on another computer for signs of hardware issues?

Unfortunately not. That’s the really strange thing, Benjamin: after these two successive failures each of the thumb drives becomes unmountable on macOS (in my case 15.4.1). Neither at the command line with the likes of diskutil, nor in the Apple Disk Utility, nor on third party apps like OwlFiles will either of the thumb drives show up!

(Although the Roon backup dialog seems to see it.)

It’s as if they’re irretrievably corrupted and will no longer mount after a/the database backup failure.

In a way, I am happy to cut my losses with the first, cheaper, Patriot 64 GB one. But the 128 GB Sandisk now seems to be irrecoverable and unable to perform any of the steps you suggest.

In fact I was also able to try to see what was on it (e.g. parts of the database) on my MacBook. Also 15.4.1. Same thing. Will not mount.

Maybe you know of a(nother) Mac app or routine (I’m comfortable with the Command line) which can let me see what state the SanDisk is in; and even try reformatting it.

Another point is this: the Patriot worked from December 2023 until late April this year. It also successfully backed up from my original Nucleus, which was replaced with a Titan earlier this year. I wonder - pure speculation - whether perhaps a recent Roon update changed the workings of RoonOS and exFAT.

No accusations!

Just a possible troubleshooting step. I ask this because - as I say - the Patriot worked perfectly until… perhaps its first fail does co-incide with the most recent Roon update. Just a thought.

Although this would seem to be contradicted by the fact that I did get the newer, 128GB Sandisk to back up once - before it too failed.

One other thing to try would be reformatting one of the drives to EXT4 if you’re comfortable doing that. I’d be curious to see if you run into the same failures.

I can certainly try to do that if I can get either of the thumb drives to mount!

Thanks again for your persistence and insights. I’ll await your suggestions, Benjamin!

[benjamin]

Hey @Mark_Sealey,

Thank you for the follow-up! I think all your thoughts above are absolutely valid - just as a refresher for me, do you host your local library within the internal storage SSD within the Nucleus itself?

After looking at another fresh diagnostic report from your Nucleus, we did find a point of corruption - but not with your current Nucleus database, we believe it to be a corrupted backup folder within both drives.

Specifically, the manifest file (b_20250202205818_...) inside a previous backup is unreadable or incomplete. This doesn’t mean your current database is corrupt — just that Roon can’t use that particular backup as a restore point.

Let’s see if manually removing the specific folder may help.

Locate the folder: /RoonBackups/b_20250202205818_4ed00e30-4565-4ad0-8619-9a239e25a057 and delete it manually.

After deleting the corrupt entry, run a new backup and see how things go.

[Mark_Sealey]

Hi @benjamin; thanks for your follow up!

My replies inline:

@benjamin

…do you host your local library within the internal storage SSD within the Nucleus itself?

Yes; that’s right.

And - until now - I’ve been running two backup routines (from Roon’s Settings > Backups > Backup now > Select Location.

1. via a SMB share - permanently mounted to my iMac, where the Roon app is located. Daily (sometimes more frequent: I’m obsessive!)
2. to one of these two exFAT-formatted Thumb drives, only mounted once a week and run then.

After looking at another fresh diagnostic report from your Nucleus, we did find a point of corruption - but not with your current Nucleus database, we believe it to be a corrupted backup folder within both drives. Specifically, the manifest file (b_20250202205818_...) inside a previous backup is unreadable or incomplete. This doesn’t mean your current database is corrupt — just that Roon can’t use that particular backup as a restore point.

That’s encouraging, isn’t it

Would it account for the fact that, when I start the exFAT/Thumb drive backup Roon does show everything from ‘Select this folder’ (where it can always actually see the Thumb drive) to the end of ‘Transferring’; and only then does it fail?

Let’s see if manually removing the specific folder may help.
Locate the folder: /RoonBackups/b_20250202205818_4ed00e30-4565-4ad0-8619-9a239e25a057 and delete it manually.

Thanks, Benjamin. Will do. But I fear I’m going to ask you for another piece of help, please:

1. is that manifest file in a(n originally source) backup on my Nucleus, or a backup completed - albeit with corruption - on my iMac? Or even only on the Thumb drive, which - I can see - would defeat a backup routine?
2. in either case, may I ask you for what you expect would be the full(er) path, please… I only see two digit directory names like ‘0b’ and longer files nested inside each but so far I can’t find any with an underbar/underscore.

Would you kindly explain what you advise is the best way safely to delete it once I know where it is, please, Benjamin. Thanks again!

[benjamin]

Hi @Mark_Sealey,

@Mark_Sealey

Would it account for the fact that, when I start the exFAT/Thumb drive backup Roon does show everything from ‘Select this folder’ (where it can always actually see the Thumb drive) to the end of ‘Transferring’; and only then does it fail?

I believe so, yes!

@Mark_Sealey

is that manifest file in a(n originally source) backup on my Nucleus, or a backup completed - albeit with corruption - on my iMac? Or even only on the Thumb drive, which - I can see - would defeat a backup routine?

Based on your Nucleus logs, we’re only seeing the error tied to the thumb drive - if locating the specific folder is proving difficult, you could also simply relocation/delete all older backups (or, at least the backups that date to the time you started experiencing this issue) and see if that clears things up for you.

Otherwise, you can locate a specific backup like b_20250202205818_4ed00e30-4565-4ad0-8619-9a239e25a057:

1. Open the root backup folder (e.g. /RoonBackups).
2. Use your operating system’s file search function to search for part of the backup name — for example, search for just b_20250202205818 or 4ed00e30 (without quotes).
3. You should find a file (not a folder) with the full name you’re looking for, nested somewhere inside one of the hashed directories.

Let me know if this helps at all!

[Mark_Sealey]

Hello again, @benjamin; thanks for your reply!

@benjamin

…we’re only seeing the error tied to the thumb drive…

which I’m encouraged by - for obvious reasons !

But I’m still not having any success searching for b_20250202205818 or 4ed00e30 etc.

You may remember that neither thumb drive appears usable after each backup failure: neither mounts to APFS on my iMac.

Nor using OwlFiles.

Would you advise of another way to do this, please - diskutil list also fails to reveal the (exFAT-formatted) thumb drive when mounted directly to the Nucleus.

I can see it from both the Roon Settings > Backup > Backup now > Backup > Select Location, however, and Settings > Backup > Finds backups > Browse…

But after single-clicking on, say, RoonBackups I can see how to and/or am not familiar with searching in that hierarchy from Roon.

Where I can get to a database backup, however is mounting my Nucleus from the iMac’s Finder and navigating to:

/Volumes/Data/Storage/TitanBackup_SanDisk_3_2_Gen_1_5B4C0AB0D882_6811-3197-p1

However strings corresponding to that file do not show up in a search:

iMac-Pro:TitanBackup_SanDisk_3_2_Gen_1_5B4C0AB0D882_6811-3197-p1 mark$ find ./RoonBackups b_20250202205818_4ed00e30-4565-4ad0-8619-9a239e25a057
… … …
find: b_20250202205818_4ed00e30-4565-4ad0-8619-9a239e25a057: No such file or directory

So I know I must be doing something wrong.

I just ran - and had fail - another Backup. Does the log for 12:33:31 PDT show the full path to the file, and its location? I think I must have to look on the Thumb drive, mustn’t I?

And not on the Nucleus itself?

Thanks in advance for your correction/direction, Benjamin, please… .

[vadim]

Hello @Mark_Sealey,

Thank you for providing the timestamp — it greatly helps with our investigation.

Upon reviewing the logs, I noticed that each time the file upload reaches approximately 92–93%, the following error occurs:

05/09 19:33:31 Trace: [backup] uploading files. bytes transferred: 658741758/706967164 (93%)
05/09 19:33:31 Warn: [backup] failed to sync: putfile hash: AttachedDir:/roon/sys/storage/mounts/TitanBackup_SanDisk_3_2_Gen_1_5B4C0AB0D882_6811-3197-p1/RoonBackups/cac1a178-32b7-4179-8afc-eebac8758421/ab/e3/abe3fb26bccb91bf0cdef2a44b6e8a2787c7d22980cc6fe0ffb551861b3962b3: Result[Status=UnexpectedError, ErrorText=System.IO.IOException: Input/output error : '/roon/sys/storage/mounts/TitanBackup_SanDisk_3_2_Gen_1_5B4C0AB0D882_6811-3197-p1/RoonBackups/cac1a178-32b7-4179-8afc-eebac8758421/ab/e3/.

This indicates that Roon was unable to complete the backup due to an I/O (Input/Output) error related to your external USB drive (TitanBackup_SanDisk_3_2_Gen_1).

Simultaneously, your system logs show:

exFAT-fs (sdb1): error, found bogus dentry(510) beyond unused empty group(509)
exFAT-fs (sdb1): Filesystem has been set read-only

Summary of the Issue:

• The backup is failing due to filesystem corruption on your exFAT-formatted drive.
• The OS has automatically remounted the drive in read-only mode to prevent further damage.

Recommended Steps:

On Windows:

1. Eject the drive and connect it to a Windows computer.
2. Open Command Prompt and run:

chkdsk X: /f

3.(Replace X: with the actual drive letter of your USB drive.)*

This will scan and attempt to repair the file system.

On macOS:

• macOS does not include built-in tools to repair exFAT.
• You may try third-party utilities such as DiskWarrior, but success is not guaranteed.
• Alternatively, reformatting the drive using Disk Utility can help, but please be aware that this will erase all data.

[Mark_Sealey]

Hello, @vadim - and thank you yet again for your quick and comprehensive reply!

@vadim

Thank you for providing the timestamp — it greatly helps with our investigation.

Always happy to help you help me .

Upon reviewing the logs…
== snipped ==

I see. Thanks. Do we still believe, Vadim, one of these three explanations:

1. that this is an actual (‘hardware’) error at the same place (<10% before completion) on each of the two thumb drives
2. that there is a specific file (@benjamin previously identified b_20250202205818_4ed00e30-4565-4ad0-8619-9a239e25a057 but I am unable to find that)
3. that the external thumb drive could - of all things - actually be FULL!

?

Recommended Steps:

On macOS:

• macOS does not include built-in tools to repair exFAT.
• You may try third-party utilities such as DiskWarrior, but success is not guaranteed.

As I say, I am concerned here: I would expect the second drive to fail - as it did - if there is a corrupted file (circumstance #2 above).

But because I bought the second (128 GB) thumb drive and it also failed at my second attempt to perform the backup, regretfully, I am wary of bying yet another one and having it too fail for the same reason. Money wasted. I’m sure you can understand that .

• Alternatively, reformatting the drive using Disk Utility can help, but please be aware that this will erase all data.

As I say, neither of the exFAT thumb drives mounts or is in any way visible on my iMac.

So, may I ask you to explain, please, how exactly I can find the apparently corrupt file, b_20250202205818_4ed00e30-4565-4ad0-8619-9a239e25a057 using either a Roon tool or process etc - and delete it in the hope that the backup can then proceed?

Thanks!

[vadim]

Hello @Mark_Sealey,

Could you please attach a new thumb drive to the Titan? I’d like to review the output of the mount command as captured in our diagnostic data.

[Mark_Sealey]

@vadim,

Of course .

It’s a very old thumb drive (< 1GB!).

ExFAT successfully formatted by Apple Disk Utility just now.

Mounted as shown here around 12:30 PDT (c. 19:30 UTC).

Still attached…

Thanks!

[vadim]

Hello @Mark_Sealey,

Based on the diagnostic data, we can see that the following thumb drive has only 62.3 MB of available space:

/dev/sdb2  62.3M  32.0K  62.2M  0%  /roon/sys/storage/mounts/ExFAT_Thumb_M-Sys_DiskOnKey_0B0DB304200083F8_6822-4AC8-p2

This suggests that the drive—and possibly your other thumb drives—may not have been formatted to use their full storage capacity.

[Mark_Sealey]

No, they were 64 GB and 128 GB.

This was a test: rather than risk damaging a new (larger) one, I dug out a very old one I have no use for - except to allow you to see what might be going on.

What else can you deduce from this, @vadim + OK to unmount now?

[vadim]

Hello @Mark_Sealey,

Could you kindly attach the 128GB drive to the Nucleus and let us know once it’s connected? Since it’s a new drive, there’s no risk of losing any data.

Once it’s connected, I’ll check its size and make sure everything is recognized properly.

[Mark_Sealey]

Gladly, @vadim!

@vadim

…attach the 128GB drive to the Nucleus and let us know once it’s connected…

It’s just after 11:00 PDT (18:00 UTC).

Attached.

Roon sees it:

No backups run.

Since it’s a new drive, there’s no risk of losing any data.

Just to be 100% clear, please: that drive is not ‘new’. It’s the replacement I bought when the 64 GB failed. This one (the 128 GB Sandisk) ran only one backup successfully; and then either failed/became corrupted or was put into Read Only state. I cannot mount it on macOS.

Once it’s connected, I’ll check its size and make sure everything is recognized properly.

Understood. Thanks.

Also, given that @benjamin suspects at least one corrupt file, please will you tell me how I can locate that and remove it.

Was that helpful, please, @vadim? I shut down the server and ejected the thumb drive at about 14:24 PDT (21:24 UTC) because it was getting warm

Thanks!

[benjamin]

Hi @Mark_Sealey,

As a simple next step - since you only have a single backup on the issue drives, could you attempt to reformat the drives using another method outside of Disk Ultility via your Mac?

This would clear any issue files, and would present a clean state to see if the issue reproduces. Let me know if this is possible!