Backup process makes client show no free space left on a Windows 7 dynamic volume

Hi everyone,

I have a Windows 7 client for which I back up files. The files that are backed up are stored on a dynamic volume made up of two 4 TB hard drives and, at the moment, there is approximately 1.5 TB of free space on this volume.
But when a backup occurs, the free space on the backed up volume drops to 0 just after the file indexing step, stays at 0 for a while, and then returns to the normal value. The backup process does not seem to be affected, but I have software running on this client which then fails due to an insufficient disk space error.

Is this an expected behavior of the backup process ? Is there a way to prevent it ?

In the UrBackup Administrators Guide, see 8.1.14 Global soft file system quota. Set this to a smaller percentage such as 90% or smaller to leave room for shared use of your backup storage volume.

Thank you for your answer, but I think you misunderstood me.
The remaining free space on the client’s hard drive drops to 0, not the remaining space on the backup storage volume.
I will modify my original message to be clearer.

Sorry for misunderstanding you. UrBackup uses Windows Shadow Storage to allow backing up open files that may change during backup. The size of the shadow copies depends on how much is changing while the backup is running. If you are unable to free additional space on the Client hard drive (Disk Cleanup, delete files in AppData\Local\temp and \Windows\temp, etc.) you may need to reduce the number of items being backed up. Managing the space used for shadow copies is discussed elsewhere.

UrBackup comes with a standard list of excluded files/folders, but I have needed to add to that list, mostly to avoid backups of rapidly-changing data such as antivirus signatures and Internet browser cache files. This data is both temporary and automatically rebuilt as those programs run, and only waste time and space for backups. Many of these folders lie hidden in the \AppData hierarchy which is automatically included when selecting C:\Users.

If you really need all the files currently selected, you might want to split the backup into virtual sub clients to perform your backups in two or more pieces. This process is covered in more detail in various messages in this forum.

I found out that it is possible to manage the way Shadow Storage works for a specified volume.
I will try to use the vssadmin command line to reduce the max space available to shadow storage to see if I can workaround my problem that way (something like vssadmin Resize ShadowStorage /For=D: /On=D: /MaxSize=5GB or eventually to move the shadow storage on another drive).