Error when adding --use-fs-snapshot Backup Flag

[kianfotovat]

Hello, I've used Backrest to add a Repository and configure a Plan. I'm using Backblaze B2 as my storage provider with the S3 backend in restic/Backrest (although I have the same issue with the B2 backend anyways).

I'm currently testing on some useless files in My Documents directory. This means I haven't run into file locks yet. When I first set up and ran my plan, I was able to backup without any issue. I can use Backrest's Snapshot Browser or other tools to explore the backup and download files.

After reading more of the restic docs, I decided to pass the --use-fs-snapshot flag since I will eventually want to backup most of this disk, including files that could potentially be in use. I added the flag like this:

but I keep getting the following error:

[restic] command: C:\Program Files\restic\restic.exe C:\Program Files\restic\restic.exe backup --json C:\Users\Kian\Documents -o sftp.args=-oBatchMode=yes --exclude-caches --tag plan:b2-desktop --tag created-by:backrest-server-desktop --parent [id] --verbose --use-fs-snapshot

[tasklog] 14:24:04.339Z error backup for plan "b2-desktop" task failed {"error": "failed to backup: command \"C:\\\\Program Files\\\\restic\\\\restic.exe backup --json C:\\\\Users\\\\Kian\\\\Documents -o sftp.args=-oBatchMode=ye...\" failed: exit code 1: backup failed\nprocessing command output: no summary event found", "duration": 3.0197118}

I also tried specifying -o vss.provider=MS but it had no effect.

I tried to run the restic command on its own (after adding the necessary -r flag and setting AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY in my cmd environment), specifically:

restic backup C:\Users\Kian\Documents -o sftp.args=-oBatchMode=yes --exclude-caches --tag plan:b2-desktop --tag created-by:backrest-server-desktop --verbose --use-fs-snapshot -r s3:s3.us-east-005.backblazeb2.com/[my-bucket-name]

This worked perfectly fine. I ran it a couple more times to be sure and it worked every time. Example output:

repository [id] opened (version 2, compression level auto)
using parent snapshot [id]
load index files
[0:00] 100.00%  3 / 3 index files loaded
start scan on [C:\Users\Kian\Documents]
start backup on [C:\Users\Kian\Documents]
creating VSS snapshot for [c:\]
successfully created snapshot for [c:\]
mountpoints in snapshot volume [c:\]:
 - c:\programdata\microsoft\windows\containers\baseimages\f2d5abdf-1a2a-4fc4-8473-4d92d5f407ce\baselayer\ (not snapshotted)
scan finished in 4.849s: 31848 files, 5.447 GiB

Files:           0 new,     0 changed, 31848 unmodified
Dirs:            0 new,   745 changed,     0 unmodified
Data Blobs:      0 new
Tree Blobs:      0 new
Added to the repository: 0 B   (0 B   stored)

processed 31848 files, 5.447 GiB in 0:19
snapshot d187ad9e saved

I suspect it has something to do with the double-outputting of restic's path in the Backrest-generated command, but the same command/plan without --use-fs-snapshot works fine (and still contains the double-output) so I'm really not sure.

Thanks in advance for the help, and thanks to the creator+maintainers for the great project :)

[garethgeorge]

Hi -- thanks for the report, I've seen a few reports of similar behavior on windows that I have yet to pin down. I've published a new binary 1.8.1 with some changes simplifying the command building logic and adding some additional clarity to the logging.

Would you mind retrying your backup on the new version?

[kianfotovat]

Thanks for the response! Just downloaded and installed 1.8.1 over 1.8.0. The double printing of my restic path is fixed but I still get the same error.

[restic] command: "C:\\Program Files\\restic\\restic.exe backup --json C:\\Users\\Kian\\Documents -o sftp.args=-oBatchMode=yes --exclude-caches --tag plan:b2-desktop --tag created-by:backrest-server-desktop --parent 56e66bceaa3f5aceef7464378747f7efcc9a630f88012850f41f69273fd0693e --verbose --use-fs-snapshot"

[tasklog] 07:51:44.029Z error backup for plan "b2-desktop" task failed {"error": "failed to backup: command \"C:\\\\Program Files\\\\restic\\\\restic.exe backup --json C:\\\\Users\\\\Kian\\\\Documents -o sftp.args=-oBatchMode=ye...\" failed: exit code 1: backup failed\nprocessing command output: no summary event found", "duration": 3.1315172}

Not sure if there are additional logs I could/should be looking at, if so please let me know and I'll be happy to provide them!

[downloaderfan]

I'm too facing the same issue on Windows(and macOS too, but I'm aware Restic doesn't support APFS snapshots yet so the parameter is moot).

Passing --use-fs-snapshot leads to error

 failed: exit code 1: backup failed
processing command output: no summary event found

Removing the parameter causes backup to run no problem.
Using v1.8.1.

Let me know if you need more details.

[downloaderfan]

@garethgeorge @kianfotovat Ok, decided to spend an hour on this issue today & figured it out.

On Windows, for any application to use VSS, it needs to run as admin. Backrest currently runs as a normal user on startup, thus when it tries to take a VSS snapshot, it fails.

The issue is, Backrest doesn't print the error properly from Restic, otherwise this would have been very clear. I copied the command Backrest generates and ran it in CMD, there I got the error clearly.

{"message_type":"exit_error","code":1,"message":"failed to load snapshot 2b4e22h5: \u003csnapshot/2b9e22c293\u003e does not exist"}

At %LOCALAPPDATA%\Programs\Backrest, there are 2 Backrest executables i.e. backrest-windows-tray.exe and backrest.exe.

backrest-windows-tray.exe is set to start at boot, which also starts backrest.exe automatically. So killing both processes using Task Manager and starting backrest-windows-tray.exe as admin would resolve the issue.

If you want to automate this, disable backrest-windows-tray.exe at Settings --> Apps --> Startup, then use Task Scheduler to start backrest-windows-tray.exe at boot as admin. (Plenty of guides available online for this.)

[kianfotovat]

Thanks for the update! I was away on vacation but I've just tested my backup again but with Backrest running as admin and it worked perfectly.

Thank you again for looking into this and creating backrest in the first place!