US Patent 9817840 Common file caching for virtual private servers

A host runs an operating system kernel. A plurality of virtual private servers (containers) is supported within the kernel. The containers use the same files. A template cache has pre-calculated file checksums. The checksum is calculated each time the file is created and/or modified. Each file has an inode containing an attribute indicating whether the checksum is calculated and stored along with the file. If the checksum is present, the process is redirected to access the file with the same inode in the shared disk cache.