Server freeze when Status: Snapshot - for 20 Seconds

Hello,

i have here a Windows Server 2008 R2 Standard Server with a Raid 6  - 47 TB Volume ... File Share Services running with 25 Shares

Backup Exec 2012 is running.

Problem: Backup Process:  Snapshot runs, freeze the Server for 20 Seconds ... when the Snapshot is ready, it's all ok.

In the 20 Second is the Server complett not available ( Ping, Share, RDP ...etc )

The Backup failed with: Communication Error

Any Idea ?

Regards,
Christian