Consider “You install Microsoft Forefront Threat Management Gateway 2010 Standard Edition on Hyper-V virtual machine, and configure TMG 2010 to use all available space on one disk for Web caching. You protect this VM by using System Center DPM2010 or DPM2007. In this scenario, you cannot create recovery points for protected VM. Additionally, you receive error message (see pic),” revealed Microsoft via KB981948. This problem occurs because there’s no available space on disk used for Web caching, thus DPM cannot create a shadow copy. To resolve this problem, increase the capacity of volume used for Web caching: Click Start, point to Programs, point to Microsoft Forefront TMG, and then click Forefront TMG Management; In Microsoft Forefront TMG, expand TMGServerName, and then click Web Access Policy; Under Related Tasks in right side pane, click Configure Web Caching on Tasks tab; Click Cache Drives tab, and then click Configure; In Define Cache Drives dialog box, select a drive that has sufficient space. Then, type desired cache size in Maximum cache size (MB) box, click Set, and then click OK.