This article describes the cause and possible solutions for the error: Fatal I/O error on .datto: #112 on write: there is not enough space on the disk.
The error code -112 is an official Microsoft System Error code for "There is not enough space on the disk."
For more information about the error code, check out the Microsoft knowledge base:
There are a number reasons this error can occur such as:
- This is commonly seen on machines which have protected volumes that have less than 20% free space.
- This can also appear if the Datto device doesn't have enough space to accept the backup.
- There may be corruption in transfer of the backup image across the network.
- Rule out any processes that are taking up large amounts of resources. Datto recommends maintaining at least 30% free space per protected volume. A minimum of 20% free space per protected volume, and 1 GB of RAM, must be available at all times on the production machine. If resources fall below these thresholds, backups will fail. Figure 1 explains utilization levels in detail.
0 – 70%
Utilization is good.
71 – 80%
Utilization is outside optimal limits. Monitor the volume growth and look at cleaning up unnecessary files and moving non-essential data to other storage.
81 – 100%
Volume is becoming critical. Snapshots will start to fail, disk queue lengths will increase. Create space.
- Exclude all Recovery or SRP partitions from the Advanced Options on the agent tab.
- Check networking and other connections to the target machine.
- This error may appear if multiple base images are running from the same protected machine.
- Try to write a Shadow Copy of the volume as a test from the Shadow Copy or a Windows Backup to determine if the VSS writers can actively write a copy.
- Have Datto technical support verify the device storage pool is healthy.