Troubleshoot file system transfers

This document describes how to troubleshoot and resolve transfer and agent issues, and where to find agent logs to help you troubleshoot issues.

Errors

The following table describes transfer error messages, and how to resolve them:

Error message	Error type	What the error means	How to resolve the error
Modified during transfer	FILE_MODIFIED_FAILURE	The source file was modified during the transfer each time that Storage Transfer Service attempted to copy the source file.	Prevent writes to the specified file during the next Storage Transfer Service operation.
Failed to transfer	PRECONDITION_FAILURE	The Cloud Storage object associated with the source file was modified each time that Storage Transfer Service attempted to upload the file.	Prevent multiple transfer jobs from writing the same file to the same Cloud Storage bucket by using unique Cloud Storage object prefixes when you create transfer jobs.
Source directory not found	SOURCE_DIR_NOT_FOUND	Either the specified source path is incorrect, or the path is correct but not all agents have access to the path.	Check the transfer job configuration and verify that: The listed source path is correct Each agent has access to the directory
Could not find the job's source or destination directory	ROOT_DIR_NOT_FOUND	Either the specified source/dest path is incorrect, or the path is correct but not all agents have access to the path.	Check the transfer job configuration and verify that: The listed source/dest path is correct Relevant agents have access to the directory
File not found	FILE_NOT_FOUND_FAILURE	The source file was found, but deleted before it was transferred to Cloud Storage.	If the file was mistakenly deleted, restore it so that the next transfer job can upload it.
Failed to find the destination bucket	BUCKET_NOT_FOUND	The destination bucket doesn't exist in Cloud Storage.	Verify that the destination bucket spelling is correct and that it exists.
Failed to find an internal metadata object	METADATA_OBJECT_ NOT_FOUND_FAILURE	Storage Transfer Service stores metadata in the destination bucket with the prefix `storage-transfer`. If the metadata files are deleted before their corresponding transfer operations complete, then this error is displayed.	Avoid deleting objects with the prefix `storage-transfer/` in the destination bucket until after all transfer jobs complete.
Failed due to invalid file name	INVALID_FILE_NAME	The path of a source file is invalid.	Verify and fix the specified file path. Verify that the path uses characters that are supported by Cloud Storage.
Failed due to invalid storage class	INVALID_FILE_STORAGE_CLASS	The storage class for the given source does not allow reads.	Find the documentation for your cloud provider to determine how to get the data into a storage class that allows copying the data out.
Failed due to invalid resumable upload session URI	SESSION_URI_INVALID	The resumable upload ID or session URI is expired or cancelled.	The failure is being retried incorrectly. Please contact support.
Failed due to invalid file size	INVALID_FILE_SIZE	The file size is invalid.	Verify file size is >= 0 and <= 5 TiB (max Cloud Storage object size) for transfers to Cloud Storage.
Failed due to permissions	PERMISSION_FAILURE and UNAUTHENTICATED	A transfer agent didn't have sufficient permissions to perform an operation. There are two possibilities for this error: An agent had insufficient Google Cloud permissions. An agent was unable to read a file or directory due to insufficient permissions on the source file system.	Verify the following: Ensure that your agents have the following IAM roles: `storagetransfer.transferAgent` `storage.admin` for all destination buckets Either of these roles can be granted to a service account that is used by the agents, or a user with these roles can use their default credentials when installing agents. Ensure that all paths on the source file system are readable by each agent.
Object is subject to bucket's retention policy and cannot be deleted, overwritten or archived	PERMISSION_FAILURE	The bucket has a retention policy in effect and the object already exists in the bucket. Storage Transfer Service cannot overwrite existing objects in the bucket. This error can be displayed if the file changed at the source, or if Storage Transfer Service attempts the upload twice due to network conditions and the first upload succeeded.	Verify that the data in your Cloud Storage bucket matches your expectations. You can confirm that the size and modified time (mtime) of the source files match their Cloud Storage object counterparts by re-running the job and confirming that there are no errors.
Service lacked sufficient permissions	SERVICE_PERMISSION_FAILURE	Storage Transfer Service didn't have sufficient permissions to perform an operation.	Storage Transfer Service uses a Google-managed service account, typically in the format of `project-PROJECT_NUMBER@storage-transfer-service.iam.gserviceaccount.com`, to access resources. To determine your specific `PROJECT_NUMBER`, use the `googleserviceaccounts.get` API call. Verify that the service account has the following roles: `roles/storagetransfer.serviceAgent` for the project. `roles/storage.admin` for all destination buckets.
Agent unsupported	AGENT_UNSUPPORTED_VERSION	The agent version is no longer compatible with Storage Transfer Service.	This is a temporary error, related to a bad agent update. If it occurs, do the following: Stop all of your agents. Pull the latest docker image by running: `sudo docker pull gcr.io/cloud-ingest/tsop-agent` Issue the Docker `run` command to start all of your agent containers. If the issue persists, reach out to your support team.
Failed due to hash mismatch	HASH_MISMATCH_FAILURE	Each time Storage Transfer Service tried to upload this file, the uploaded bytes were corrupted. This resulted in the hash of the on-premises file not matching the hash of the resulting Cloud Storage object.	This error may be caused by a number of potential issues. If you see a small percentage of hash mismatch failures (less than 1%) in a large transfer, retry the failed files. If you see a large percentage of hash mismatch failures (1% or greater), we recommend investigating potential memory, CPU, or other hardware failures on the agent machine.
Failed due to an unsupported file mode	UNSUPPORTED_FILE_MODE	Storage Transfer Service encountered a file with an unsupported mode, such as a device, socket, named pipe, or irregular file.	Remove these special file types from the source directory.
Failed due to an error in the file system	FILESYSTEM_ERROR	An agent encountered a file system or operating system error when performing a file system operation such as read, seek, or stat.	Read the failure description to understand which file system operation failed. Ensure the file system is accessible to the on-prem agent and responsive to basic file operations.
Failed due to an unknown error	UNKNOWN_FAILURE	An unexpected error occurred.	Read the failure description. If the failure description does not contain sufficient information to resolve the issue, please contact support.
Failed due to an invalid specification	INVALID_SPEC	The agent received a corrupted internal specification.	Check for data corruption on agent hosts and contact support if you cannot find any.
Failed due to an empty or invalid manifest file	CONFORMANCE_FAILURE	The agent cannot read or get valid CSV bytes due to invalid formatting or CSV entries.	Ensure that the manifest entries are valid file paths. If the failure description does not contain sufficient information to resolve the issue, please contact support.
Falling back to resumable uploads instead of multipart uploads due to permission denied error	PERMISSION_FAILURE	Multipart uploads have been enabled for this transfer, but the correct permissions have not been set on the bucket.	Refer to the Multipart uploads section of File system permissions for the required permissions.

Viewing agent logs

Agent logs contain information relevant to agent processes, and can help you troubleshoot agent connection problems. If your agents are listed as connected in Google Cloud console and you are experiencing transfer failures, see Viewing errors to view a sample of transfer errors. To view logs that contain a record of every file Storage Transfer Service considered during a transfer, see Viewing transfer logs.

By default, agent logs are stored in /tmp. You can change the location with the --log-dir=logs-directory command-line option.

The logs are named:

agent.hostname.username.log.log-level.timestamp

Where:

hostname - hostname the agent is running on.
username - username running the agent.
log-level is one of:
- INFO - informational messages
- ERROR - errors encountered during transfer, but that don't prevent the transfer job from continuing.
- FATAL - errors encountered that prevent the transfer job from continuing.
timestamp - timestamp in YYYYMMDD-hhmmss.thread-id format.

The logs directory contains symlinks to the most recent logs for each of the priority levels:

agent.ERROR
agent.FATAL
agent.INFO

Slow transfer speed

If your data is taking a long time to transfer, check the following:

The read throughput of your file system should be approximately 1.5 times your desired upload speed. You can use FIO to test the read throughput of your file system.

Install fio:
```
 sudo apt install -y fio
 
```
Create a new directory fiotest:
```
 TEST_DIR=/mnt/mnt_dir/fiotest
 sudo mkdir -p $TEST_DIR
 
```
Test read throughput:
```
 sudo fio --directory=$TEST_DIR --direct=1
    --rw=randread --randrepeat=0 --ioengine=libaio --bs=1M --iodepth=8
    --time_based=1 --runtime=180 --name=read_test --size=1G
 
```
After you run the commands above, Fio generates a report. The line labeled "bw" represents the total aggregate bandwidth of all threads, and it can be used as a proxy for read throughput.
Use iPerf3 to check your available internet bandwidth to Storage Transfer Service.
Make sure each of your transfer agents have at least 4 vCPU and 8GB of RAM.

If you've checked the conditions above and are still experiencing long transfer times, you can add additional agents to increase the number of concurrent connections to your data's file system.

For more information on how to maximize the performance of your transfer agents, see Agent best practices.

Troubleshooting agent errors

The following sections describe how to troubleshoot and resolve transfer agent errors:

Agents are not connected

If transfer agents are not displayed as connected within Google Cloud console:

Verify that agents can connect to Cloud Storage APIs:
1. Run the following command from the same machine as the transfer agent to test the agent's connection to Cloud Storage APIs:
  
  gcloud storage cp test.txt gs://my-bucket
  
  Replace:
  
  my-bucket with the name of your Cloud Storage bucket.
If your project uses VPC Service Controls, view the agent logs for errors. If VPC Service Controls is misconfigured, the INFO agent logs will contain the following error:

Request is prohibited by organization's policy. vpcServiceControlsUniqueIdentifier: id

In this output:
- id is the VPC Service Controls error's unique id

Agents are connected but jobs fail

If agents are displayed as connected but transfer jobs fail, check the error details of the failed jobs.

Proxy rejects IP addresses

If you run behind a proxy like Squid and you use an allowlist, you may see requests being denied because of IP addresses being used instead of hostnames.

To resolve this issue, use the docker run command to run the agents and add the following flag:

--transfer-service-endpoint=storagetransfer.googleapis.com:443

If you use an alternative endpoint to reach googleapis.com (e.g. for Private Service Connect), replace googleapis.com with the alternative endpoint.