1691 SafeGuard Encrypted Virtual Disk Aggregate SafeGuard PrivateDisk is disk encryption software produced by Sophos. The .hdr file appears to contain header information, while the .vol file is the encrypted virtual disk. 1 Digital Preservation Department / The National Archives 06 Jun 2016 06 Jun 2016 fmt/887 PUID vol File extension hdr File extension 1236 PDisk (Private Virtual Disk) 507269766174654469736B205669727475616C204469736B {PrivateDisk Virtual Disk} 1 Absolute from BOF 0 0 507269766174654469736B205669727475616C204469736B