Rclone rcat + chunker backend still spooling to local disk causing "no space left on device" (Target: 1fichier)

Suspected Bug
1

Hello rclone community,

I am trying to stream a large backup (~460GB) directly to 1fichier without storing it locally, as the source machine has limited free space on the system partition (~90GB).

I am using tar to create an archive on the fly and piping it to rclone rcat. Since 1fichier does not support streaming files of unknown size, I set up a chunker backend to chop the stream into segments.

However, rclone insists on spooling data to /tmp/rclone-spool... until the disk fills up, causing a crash. It seems it's trying to buffer the whole file (or very large parts of it) despite my attempts to force pure streaming.

Environment:

  • OS: Linux (Ubuntu 24.04)

  • Rclone Version: v1.72.1 (latest)

  • Source: Local files (piped via tar)

  • Destination: 1fichier (via chunker)

Configuration (rclone.conf):


[rmodo]

type = fichier

api_key = REDACTED

[rmodo_stream]

type = chunker

remote = rmodo:rmodo

hash_type = sha1

I rely on default chunk_size (2G) or override it via flags, but the issue persists.

The Command I'm running:

cd /path/to/source && \
tar -cf - . | \
rclone rcat "rmodo_stream:backup.tar" \
  --transfers=1 \
  --retries 5 \
  --no-check-dest \
  -v

The Error:

ERROR : backup.tar: Post request rcat error: failed to copy to temporary spool file: write /tmp/rclone-spool846153648: no space left on device
NOTICE: Failed to rcat with 2 errors: last error was: failed to copy to temporary spool file: write /tmp/rclone-spool846153648: no space left on device

What I have tried:

  1. Upgraded to rclone v1.72.1.
  2. Set --transfers=1 to prevent parallel buffering of chunks.
  3. Used --no-check-dest to avoid pre-checks.
  4. Tried setting chunk_size explicitly to 256M.
  5. Configured the remote via connection string (:chunker,remote='rmodo:rmodo',chunk_size=256M:) and via rclone.conf.

Question:
Is there a way to force rclone rcat -> chunker -> 1fichier to be strictly streaming (read stdin -> upload chunk -> repeat) without spooling significant data to tmp? Why is the spooler being triggered here despite the chunker backend?

Any help would be appreciated!

2

is this forum alive ? Bumped

3

Sure is. You missesd using the template we have for support and also including a debug log.

4

my bad, I believed it was only for "help and support" sub forum.

What is the problem you are having with rclone?

Is there a way to force rclone rcat -> chunker -> 1fichier to be strictly streaming (read stdin -> upload chunk -> repeat) without spooling significant data to tmp? Why is the spooler being triggered here despite the chunker backend?

Run the command 'rclone version' and share the full output of the command.

rclone v1.72.1

  • os/version: ubuntu 24.04 (64 bit)
  • os/kernel: 6.8.0-88-generic (x86_64)
  • os/type: linux
  • os/arch: amd64
  • go/version: go1.25.5
  • go/linking: static
  • go/tags: none

Which cloud storage system are you using? (eg Google Drive)

1fichier

The command you were trying to run (eg rclone copy /tmp remote:tmp)

cd /path/to/source && \
tar -cf - . | \
rclone rcat "rmodo_stream:/backup.tar" \
  --transfers=1 \
  --retries 5 \
  --retries-sleep 30s
  --no-check-dest \
  -vv

Please run 'rclone config redacted' and share the full output. If you get command not found, please make sure to update rclone.

[backupvm]
type = crypt
remote = rmodo:backup
password = XXX
password2 = XXX
description = encrypted repo

[rmodo]
type = fichier
api_key = XXX
description = remote modo

[rmodo_stream]
type = chunker
remote = rmodo:rmodo
hash_type = sha1

A log from the command that you were trying to run with the -vv flag

2026/01/31 23:20:05 DEBUG : rclone: Version "v1.72.1" starting with parameters ["rclone" "rcat" "rmodo_stream:/backup.tar" "--transfers=1" "--retries" "5" "--retries-sleep" "30s" "--no-check-dest" "-vv"]
2026/01/31 23:20:05 DEBUG : Creating backend with remote "rmodo_stream:/"
2026/01/31 23:20:05 DEBUG : Using config file from "/home/modo/.config/rclone/rclone.conf"
2026/01/31 23:20:05 DEBUG : Creating backend with remote "rmodo:rmodo"
2026/01/31 23:20:07 DEBUG : Chunked 'rmodo_stream:/': Target remote doesn't support streaming uploads, creating temporary local FS to spool file
2026/01/31 23:31:44 ERROR : backup.tar: Post request rcat error: failed to copy to temporary spool file: write /tmp/rclone-spool1993608178: no space left on device
2026/01/31 23:31:44 DEBUG : 3 go routines active
2026/01/31 23:31:44 NOTICE: Failed to rcat with 2 errors: last error was: failed to copy to temporary spool file: write /tmp/rclone-spool1993608178: no space left on device
5

That would be it there as rclone doesn’t think it can support streaming so it writes local.

I’d imagine if you tested 1Filchier and that streams, it would be a chunker issue.

If you simplify and test with 1filchier and then the combo to rule out any oddness with rcat by just doing a quick test file.

rclone copy somesmallfile.txt -v to rmodo -vv and check the log and to the chunker and check the log and validate it’s chunker as the problem.

6

Thank you for your support.
However, I don't quite get it. What should I look for ? a chunker problem due to the cloud provider 1fichier?

transfering a small file without chunker:

 modo@modo at 󰋜 ~ via🌱 main[$!+?] rclone copy /home/modo/regex.txt rmodo:rmodo -vv
2026/02/02 08:46:18 DEBUG : rclone: Version "v1.72.1" starting with parameters ["rclone" "copy" "/home/modo/regex.txt" "rmodo:rmodo" "-vv"]
2026/02/02 08:46:18 DEBUG : Creating backend with remote "/home/modo/regex.txt"
2026/02/02 08:46:18 DEBUG : Using config file from "/home/modo/.config/rclone/rclone.conf"
2026/02/02 08:46:18 DEBUG : fs cache: renaming child cache item "/home/modo/regex.txt" to be canonical for parent "/home/modo"
2026/02/02 08:46:18 DEBUG : Creating backend with remote "rmodo:rmodo"
2026/02/02 08:46:18 DEBUG : regex.txt: Need to transfer - File not found at Destination
2026/02/02 08:46:22 DEBUG : regex.txt: size = 78 OK
2026/02/02 08:46:22 DEBUG : regex.txt: whirlpool = 497f78d8423af4ff75e115ac1f07ee49cdba41e583c9ff100dd0db8a5ad037b232112573dc438750b1f71774ed91cbd10d86c6772803cd6cc702149f1793007a OK
2026/02/02 08:46:22 INFO  : regex.txt: Copied (new)
2026/02/02 08:46:22 INFO  : 
Transferred:             78 B / 78 B, 100%, 25 B/s, ETA 0s
Transferred:            1 / 1, 100%
Elapsed time:         3.9s

2026/02/02 08:46:22 DEBUG : 5 go routines active

transfering a small file with chunker:

 modo@modo at 󰋜 ~ via🌱 main[$!+?] rclone copy /home/modo/regex.txt rmodo_stream: -vv
2026/02/02 08:43:09 DEBUG : rclone: Version "v1.72.1" starting with parameters ["rclone" "copy" "/home/modo/regex.txt" "rmodo_stream:" "-vv"]
2026/02/02 08:43:09 DEBUG : Creating backend with remote "/home/modo/regex.txt"
2026/02/02 08:43:09 DEBUG : Using config file from "/home/modo/.config/rclone/rclone.conf"
2026/02/02 08:43:09 DEBUG : fs cache: renaming child cache item "/home/modo/regex.txt" to be canonical for parent "/home/modo"
2026/02/02 08:43:09 DEBUG : Creating backend with remote "rmodo_stream:"
2026/02/02 08:43:09 DEBUG : Creating backend with remote "rmodo:rmodo"
2026/02/02 08:43:10 DEBUG : regex.txt: Need to transfer - File not found at Destination
2026/02/02 08:43:10 DEBUG : regex.txt: skip slow SHA1 on source file, hashing in-transit
2026/02/02 08:43:16 INFO  : regex.txt.rclone_chunk.001_tsgp1a: Moved (server-side) to: regex.txt
2026/02/02 08:43:16 DEBUG : regex.txt: size = 78 OK
2026/02/02 08:43:16 INFO  : regex.txt: Copied (new)
2026/02/02 08:43:16 INFO  : 
Transferred:             78 B / 78 B, 100%, 12 B/s, ETA 0s
Checks:                 1 / 1, 100%, Listed 0
Renamed:                1
Transferred:            1 / 1, 100%
Server Side Moves:      1 @ 78 B
Elapsed time:         6.1s

2026/02/02 08:43:16 DEBUG : 5 go routines active

Does rclone try to stream with the chunker (skip slow SHA1 on source file, hasing in-transit) ?

7

We are looking to see when this:

2026/01/31 23:20:07 DEBUG : Chunked 'rmodo_stream:/': Target remote doesn't support streaming uploads, creating temporary local FS to spool file

Gets dropped in as that’s the issue for the local copy.

I don’t see that on either copy you did.

Last one would be trying rclone copy to the crypt and if that works, it’s some interaction with rclone cat.

8

Yes, the logs show that rclone copy works fine and does not trigger the spooling error. The error only appears when using rclone rcat (streaming). Since chunker is supposed to enable streaming by splitting the file, should rcat not be able to upload chunk-by-chunk without spooling the entire file locally?