DPM 2012 - SharePoint Backup Event Id 23 source: volsnap

Hi,

I run a job in DPM 2012 to backup SharePoint server, I start backup up a week ago, It's run OK.

Yesterday I saw the job fail. there is event id 23 source: volsnap "There was insufficient disk space on volume C:\...a8a7-4ed1-9d70-a359e62e3581 to create the shadow copy of volume C:\...a8a7-4ed1-9d70-a359e62e3581.  Shadow copy storage creation failed."

all other jobs are running OK.

I got enough space in all disks.

need help with this issue.

Thanks