Rclone get killed randomly when trying to sync from AWS S3 with DO Space

Yan_Cheng_Cheok · March 11, 2025, 4:36pm

What is the problem you are having with rclone?

Using Dockerized rclone/rclone:1.69

Trying to sync from source (AWS S3) to backup (Digital Ocean Space)

Randomly get killed after few hours run.

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

/data # rclone version
rclone v1.69.1
- os/version: alpine 3.21.2 (64 bit)
- os/kernel: 5.10.25-linuxkit (aarch64)
- os/type: linux
- os/arch: arm64 (ARMv8 compatible)
- go/version: go1.24.0
- go/linking: static
- go/tags: none

Are you on the latest version of rclone? You can validate by checking the version listed here: Rclone downloads

Yes. Latest version

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

Using AWS S3 as primary source. Using Digital Ocean Space as backup.

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

rclone sync s3:wenote-b spaces:wenote-b --metadata --verbose

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

/data # rclone config redacted
[s3]
type = s3
env_auth = false
access_key_id = XXX
secret_access_key = XXX
region = eu-central-1
location_constraint = eu-central-1
acl = private
provider = AWS

[spaces]
type = s3
env_auth = false
access_key_id = XXX
secret_access_key = XXX
endpoint = fra1.digitaloceanspaces.com
acl = private
provider = DigitalOcean

[wasabi]
type = s3
env_auth = false
access_key_id = XXX
secret_access_key = XXX
region = eu-central-1
endpoint = s3.eu-central-1.wasabisys.com
acl = private
provider = Wasabi
### Double check the config for sensitive info before posting publicly
/data #

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

/data # rclone sync s3:wenote-b spaces:wenote-b --metadata --verbose -v
2025/03/11 16:34:51 DEBUG : rclone: Version "v1.69.1" starting with parameters ["rclone" "sync" "s3:wenote-b" "spaces:wenote-b" "--metadata" "--verbose" "-v"]
2025/03/11 16:34:51 DEBUG : Creating backend with remote "s3:wenote-b"
2025/03/11 16:34:51 DEBUG : Using config file from "/config/rclone/rclone.conf"
2025/03/11 16:34:51 DEBUG : Creating backend with remote "spaces:wenote-b"
2025/03/11 16:34:54 DEBUG : user-1004/android-wenote-sqlite.zip: Size and modification time the same (differ by 0s, within tolerance 1ns)
2025/03/11 16:34:54 DEBUG : user-1004/android-wenote-sqlite.zip: Unchanged skipping
2025/03/11 16:34:54 DEBUG : user-10/android-wenote-sqlite.zip: Size and modification time the same (differ by 0s, within tolerance 1ns)
2025/03/11 16:34:54 DEBUG : user-10/android-wenote-sqlite.zip: Unchanged skipping
2025/03/11 16:34:54 DEBUG : user-100/android-wenote-sqlite.zip: Size and modification time the same (differ by 0s, within tolerance 1ns)

p/s I have ensure there is sufficient resource when running rclone. Here is the output from top

Mem: 1145624K used, 891108K free, 124056K shrd, 10968K buff, 272344K cached
CPU:   2% usr   1% sys   0% nic  95% idle   0% io   0% irq   0% sirq
Load average: 0.25 0.34 0.33 3/891 119
  PID  PPID USER     STAT   VSZ %VSZ CPU %CPU COMMAND
  101    14 root     S    1258m  63%   2   4% rclone sync s3:wenote-b spaces:wenote-b --metadata --verbose
   14     0 root     S     1792   0%   3   0% sh
  111     0 root     S     1764   0%   3   0% sh
  119   111 root     R     1692   0%   0   0% top
    1     0 root     S     1684   0%   0   0% /usr/sbin/crond -f -l 8

asdffdsa · March 11, 2025, 4:46pm

welcome to the forum,

what is the total number of files in the souce and the dest?
might test --disable=ListR
might test sync for directories with lots of entries. This should fix the memory usage problems.

Yan_Cheng_Cheok · March 11, 2025, 5:08pm

Hi, the number of files should be in the range of 600,000 to 700,000

The file is usually image file less than 1MB

Currently, when it fails, I will just keep re-run the same command again.

My question is, will the destination be "eventually" properly sync, or some files will be corrupted?

Thanks. I will try your suggestions.

asdffdsa · March 11, 2025, 5:09pm

if rclone is getting killed with OOM, have to assume there could be corrupt partial uploads taking up space in cloud.

--s3-leave-parts-on-error

Yan_Cheng_Cheok · March 11, 2025, 5:21pm

I didn't use --s3-leave-parts-on-error in my command, and it seems the default value is false.

If DigitalOcean Spaces implements this correctly, I assume there won't be any corrupted files.

Even if there is corruption, can rclone detect it and replace the corrupted file from the source?

asdffdsa · March 11, 2025, 5:24pm

IMO, not correct to assume.
if rclone hard crashes, then rclone might not be able to "call abort upload on a failure"
my point is no way to know for sure.

maybe or maybe not. never tested that.

asdffdsa · March 11, 2025, 6:01pm

Remove unfinished multipart uploads

Yan_Cheng_Cheok · March 14, 2025, 4:34pm

Hi, I manage to resolve the OOM issue by following the steps at

Going forward, may I know what is the recommended way, to keep both S3 and DO's Space in sync, daily?

Is using

rclone sync s3:wenote-b spaces:wenote-b --metadata --verbose

still being recommended? Or, I should use the workaround mentioned in Big syncs with millions of files · rclone/rclone Wiki · GitHub ?

Thank you.

kapitainsky · March 14, 2025, 5:17pm

Short term, workaround you mentioned is really only way.

Moving forward hopefully the proper fix already mentioned earlier will be included in the latest rclone release. If you want you can try it now. Here you can download beta version with relevant patch.

And please provide feedback here:

github.com/rclone/rclone

Excess memory use when syncing millions of files in one directory

opened 08:44AM - 25 Jul 24 UTC

zackees

bug

## Background - Amazon S3 rclone problems I'm trying to backup a datalake wit…h 100 million files at the root. They are mostly small files < 1mb. rclone was simply not designed for this use case and will eat up all available memory and then crash. There was no machine instance that I could throw at it that would fix this issue. Even running locally in a docker instance would eat up all available memory and then crash. All advice in the forums did nothing to help the situation. And a lot of people seem to be running into this. Therefore I wanted to post this here so that anyone searching for this problem can try our solution. ## Solution in a nutshell: PUT YOUR FILES INTO FOLDERS!!!! What's interesting is the behavior: rclone would never start transferring files, it would always sit there saying 0 files transferred, 0 bytes transferred, eat up all available memory before crashing with an OOM. I tried all the suggestions in the forums, reducing the buffering memory, reducing the number of checkers and transfers. Nothing worked. ## Cause & Fix Without looking at the code or doing any profiling, my hypothesis was that rclone scans an all files in a"directory" into RAM before executing on it. This seems true whether not `--fast-scan` is used or not. Obviously, having 100 million files at the root was causing our org a whole bunch of problems anyway and it's been something that I've wanted to fix for a while, so this problem gave me enough reason to go ahead and re-organize our entire datalakes. Since each file is referenced in our database with a datestamp, I was able to write python scripts that would move these files from the root into folders by the service and year-month (for example name.html -> service/2023-04/name.html) This worked extremely well and I was able to now run rclone and have it at least start transferring some files. However, there were still folders with 5+ million files, and eventually ran into the same out-of-memory error. So again, I further re-organized the files in our datalake into service/yrmo/day. And now that seems to have done the trick. rclone now consistently runs under 2GB memory and I've been able to increase the number of transfers and checkers up to 100 each and have 3mb of buffer per transfer. ## Dead ends All the advice about adjust memory buffers and number of transfers is mostly wrong. They will only cut your minimum memory usage by a constant factor, but will do very little to prevent the absolute unbounded memory that rclone uses for extremely large "directories". If you have this same problem, no amount of setting tweaking will work... you MUST re-organize your data into folders or rclone will just run out of memory every single time. If you have too many files at the root, rclone will simply never start transferring anything and just crash. If one of your subdirectories is too big, you'll get a memory pattern that looks like this: ![image](https://github.com/user-attachments/assets/cad7926e-48b7-46f7-be81-543edc896460) ## Recommendations to the Devs of rclone Please serialize your directory scans to disk if you start exceeding a certain threshold of memory or files in the current directory. You can probably just get away with just always doing that since the disk is so much faster than network anyway. I'm currently doing an inventory scan of our datalakes and 50 million files entries is only taking up 12 gb of disk without any fancy compression. I know you are storing a lot more file information, like metadata, so it could easily be double or triple that. But it is simply so much easier and cheaper to allocate disk space to a docker instance than it is to get a machine with much more ram. An additional pain point about an out of memory issue crash is that when the rclone process gets a kill signal, it will **exit 0** making it look like it succeeded. According to this thread https://github.com/rclone/rclone/issues/7966 this is a feature of linux and you must get the exit code from the operating system instead of the return value of the exited rclone process. This is super scary if you are relying on rclone to backup your datalake but in reality, it starts failing because one of your directories has millions of files in it. I know on Digital Ocean it's easy to see that a docker instance has failed, on Render.com however you'll get a "Run Succeeded" and it's not until you look at the run history that you'll see that in fact your instance ran out of memory. I'm not sure about the other hosting providers. Anyway, I'm glad this huge task is finally over with, and we have started syncing up our data for redundancy and backup purposes. So far so good! ![image](https://github.com/user-attachments/assets/5c2b7096-ade2-45d7-993e-4fd0b0f52196)