Storage Vault Locks

Magnus Box lets multiple devices back up into a shared Storage Vault at the same time. A retention pass first examines the existing data chunks, then deletes the unused ones. A backup job checks the existing chunks, uploads new ones, and uploads a backup snapshot. Multiple backup jobs can run at once safely. In Magnus Box 21.9.4 and later, backup and retention jobs can also run concurrently, using a mark-and-sweep algorithm to delete data chunks safely while other backup operations proceed.

How lock files work

To coordinate these concurrent operations, Magnus Box writes temporary text files (lock files) into the Storage Vault to signal when a retention pass is running. This mechanism works across all vault types (local disk, SFTP, S3, and so on). Other jobs read these files to detect operations already in progress.

The downside of lock files

If Magnus Box stops suddenly (for example, a PC crash), the lock files are left behind and are not deleted. Other processes then cannot tell that the original job has ended. Magnus Box surfaces this by failing the affected jobs with an error message that identifies the device and job responsible, so you can investigate before removing anything.

Example error text includes:

"Locked by user '...' on this device (PID #...) since ... (... days ago)"
"Locked by user '...' on computer '...' (PID #...) since ... (... days ago)"
"However, the responsible process might have stopped."
"If you investigate this process, and are absolutely certain it won't resume, then it's safe to ignore it and continue."

Clearing stale lock files

Once you have confirmed the responsible process is genuinely stopped and will not resume, you can remove the lock files two ways:

From the Magnus Box client: open the Account pane, right-click the Storage Vault, choose Advanced, then Clean up lock files.
Remotely, from the Magnus Box web dashboard: go to Accounts > Users > the user of the Storage Vault > Devices tab > Storage Vault tab > Unlock. This clears the lock files. After unlocking, run Apply Retention Rules Now from the same Storage Vault tab.

Warning: only unlock when you are certain no job is still running against the vault. If lock files are removed while an operation is in progress, data loss is highly likely.

Automatic unlock

Magnus Box automatically deletes stale lock files when it can determine that doing so is safe. When Magnus Box is running on the same PC as a potentially stale lock file, it checks the running processes to see whether the originating process is still active before clearing the lock.

Backup strategies to avoid lock file issues

If lock file errors show a duration of 5 minutes or less, reschedule the backups so they do not overlap.
If you see longer lock issues (hours to days), move the affected devices to separate Storage Vaults.

Recovering from unsafe unlock operations

If you see the error "Packindex '...' for snapshot '...' refers to unknown pack '...', shouldn't happen", a data file has been erroneously deleted inside the Storage Vault and data has been lost. Contact Magnus Box support for assistance.

Error: "Found X packs in index but not appearing on disk. Reindex needed!"

This means the index files reference data chunks that are no longer found in the Storage Vault. Common causes are manual file deletion, data loss on the storage platform, unsafe use of Unlock, or a retention pass running backward after a VM snapshot resumption.

To resolve it:

Toggle on Admin > Advanced Options.
Go to Accounts > Users > name > Devices tab > click Online > Storage Vault tab > Reindex.
Toggle off Admin > Advanced Options.
Return to Accounts > Users > name > Devices tab > click Online > Storage Vault tab > Apply Retention Rules Now.
Check Accounts > Users > name > Actions > View Job History > Report.
No errors indicates success: the missing chunks were located in the Storage Vault and reindexed.

Error: "<packindex/pppppppp> says <snapshot/ssssssss> depends on missing pack <data/dddddddd>, non-restorable!"

Like the reindex error above, this means a specific backup snapshot refers to data chunks that are no longer available, making that snapshot non-restorable. The causes are the same as those listed above. Contact Magnus Box support for assistance.