Backup Cache Size Exceeded

How to address Job Session errors indicating that Backup Cache Size has been exceeded

Background

What is the Veeam Backup Cache?

The Veeam Backup Cache is an optional setting that can be configured on your eSilo backup job.  It is a helpful feature that enables backups jobs to complete, even if the eSilo Backup Cloud repository is unreachable.  This can happen when the network connection drops or is unstable, or if cloud resources are busy at the time of the backup.

Where are Backup Cache files stored?

The Backup Cache is a folder on the host machine.  It’s default location is C:\VeeamCache, although you should check the cache settings in the backup job to confirm the location.  The location can be set to a removable USB.  The default size of the Backup Cache for eSilo jobs by eSilo is 20GB.  See this link for more information on Backup Cache for Veeam Agents for Windows 4.0.

What causes the Backup Cache Size to be Exceeded?

When functioning normally, cached restore points automatically sync, or upload, to the eSilo Backup Cloud once the connection is re-established, starting with the oldest first and proceeding chronologically.  After a cached restore point is synced, it is automatically deleted from the cache.  This prevents the cache from growing indefinitely.

However, if restore points accumulate in the local backup cache and it becomes full before having an opportunity to sync all restore points to the eSilo Backup Cloud, the job will error.  This error prevents the job from completing, and new restore points are not saved.  Once this happens, future backup jobs may fail until the cache is cleared–by either syncing restore points or if necessary, manually purging cached backups and retrying the cloud job.

Issue & Error Description

Backup job fails with an “Error” and one of the below messages is displayed:

“Job session for [Job Name] finished with error. Backup cache size has been exceeded”

Resolution Steps

Option 1:  Attempt to Restart the Backup Cache Sync

1. Open your system tray by clicking on the small  “ ^ ”  icon on your taskbar
2. Right click on the Veeam icon  
3. Select Pause Sync.  Select 10 minutes.
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4. Wait a few minutes, then repeat steps 1 & 2.
5. Select the option to Resume Sync (or simply wait the 10 minutes)
6. Repeat steps 1 & 2 again.  Click on Control Panel to open the Veeam Agent for Windows.
7. Select the backup job and click Backup Now.
8. Monitor the backup to confirm it completes without error.  If this does not work, proceed to Option 2.  If you have difficulty with the steps above, see this Veeam KB article.

Option 2:  Delete the Backup Cache

1. Repeat steps 1 & 2 above and select View Cache.
2. If that option is not present, you may instead select Control Panel to open the Veeam Agent for Windows
3. Click the three horizontal lines in the upper left corner to expand the menu
4. Hover over the eSilo Cloud Connect job (usually prefixed “eSilo…”) to expand the menu.
5. Select Open Backup Cache from the menu.
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6. In the Backup Cache view, click Delete Cache.
7. In the window notifying that restore points will be deleted from the backup cache, click Yes.
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   2. Note:  The first backup job session following the deletion of restore points from the backup cache must complete successfully and create backup files on the target location. During this session, Veeam Agent for Microsoft Windows will create a new map of target location data blocks in the backup cache. If you delete restore points from the backup cache, and then run the backup job when the target location is unavailable, the backup job will fail.
8. Rerun the backup job by clicking Backup Now.  If you have difficulty with the above steps, consult this Veeam KB Article on Deleting Restore Points from Backup Cache

Further Troubleshooting

If after deleting the Backup Cache files, the next job run still fails to complete, this may be an indication of an outdated reference (e.g. link_id referring to a deleted restore point) in the Backup Job metadata file (.vbm).

To resolve, eSilo Support may need to rename the existing metadata file in the repository (ex: appending “.old” to the end of the .vbm file extension) and then rerun the backup job. This will cause the Agent to regenerate the metadata file based on the Veeam Agent for Windows database residing on the local machine, and also push those that update to eSilo servers.  (Veeam Case reference 04293018).