Virtualized boot block with discovery volume

• US 8,510,352 B2
• Filed: 10/24/2008
• Issued: 08/13/2013
• Est. Priority Date: 10/24/2008
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Mehra, Karan, Thind, Ravinder S., Moss, Darren G., Ou-Yang, Darwin
• Primary Examiner(s): Casanova, Jorge A
• Application Number:
  US12/257,938
• Publication Number:
  US 20100114990A1
• Time in Patent Office: 1,754 Days
• Field of Search: 707/795, 707/796, 707/812, 707/831
• US Class Current: 707/831
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: G06F 16/1727 Details of free space management performed by the file system saving storage space on storage systems G06F3/0608; management of blocks in storage devices G06F3/064
• CPC Class Codes: G06F 16/1847 specifically adapted to static storage, e.g. adapted to flash memory or SSD
• CPC Class Codes: G06F 16/188 Virtual file systems
• CPC Class Codes: G06F 9/441 Multiboot arrangements, i.e. selecting an operating system to be loaded

Abstract

A file system independent virtualized boot block with discovery volume and cover files renders a volume visible when accessed by an accessing system which differs from a source system. For example, a downlevel operating system recognizes that data is present on a volume created in an uplevel operating system, even where the uplevel data itself may not be accessible.

Claims

1. A method comprising:

moving contents of an original boot block of a primary volume from a beginning of the primary volume to a new location in the primary volume;

providing a discovery volume in the primary volume;

configuring a virtualized boot block for the discovery volume;

providing one or more pointers in the virtualized boot block for referring a boot block access request to the new location of the original boot block for the primary volume; and

positioning at least the virtualized boot block for the discovery volume at the beginning of the primary volume so as to be initially accessed when the primary volume is accessed.

2. The method of claim 1, wherein the discovery volume is a file allocation table (FAT) volume and the primary volume is not a FAT volume.

3. The method of claim 1, wherein the discovery volume contains one or more cover files, the one or more cover files configured to appear to an accessing system to occupy physical storage media actually occupied by the primary volume.

4. The method of claim 1, further comprising returning contents of the original boot block when a read request comprising a boot block location is received.

5. The method of claim 1, further comprising using the one or more pointers for redirecting a write request to the original boot block such that the original boot block is written to and not the virtualized boot block at the beginning of the primary volume.

6. The method of claim 1, further comprising providing multiple virtualized boot blocks concurrently at more than one level in an operating system.

7. The method of claim 1, wherein the one or more pointers point to a metadata data structure comprising information referring to the original boot block.

8. The method of claim 1, wherein data on the primary volume is encrypted and the virtualized boot block is not encrypted.

9. A system comprising:

a processor; and

an operating system executable by the processor to perform operations, the operations comprising;

reading a virtualized boot block provided at a beginning of a primary volume;

following a pointer stored in the virtualized boot block pointing to a data structure comprising information referring to an original boot block for the primary volume, the original boot block having been relocated to a new location within the primary volume;

returning contents of the original boot block when a read request comprising a boot block location is received; and

redirecting a write request comprising a boot block location to a location of the original boot block such that the contents of the original boot block are overwritten and not the data in the virtualized boot block at the beginning of the primary volume.

10. The system of claim 9, wherein the virtualized boot block comprises a discovery volume boot block for a discovery volume in the primary volume.

11. The system of claim 10, wherein the discovery volume comprises entries for one or more cover files, the one or more cover files configured to appear to an accessing system to occupy physical storage media actually occupied by the primary volume.

12. The system of claim 9, the operations further comprising providing multiple virtualized boot blocks concurrently at more than one level in an operating system.

13. The system of claim 9, the operations further comprising mounting the primary volume in an operating system.

14. The system of claim 9, wherein the virtualized boot block is located in a boot sector of a partition of a physical storage device, the partition corresponding to the primary volume.

15. A computer readable storage memory storing data comprising:

a data structure written in a boot sector of a primary file system, the data structure including a discovery volume having a virtualized boot block positioned to be initially accessed when the primary file system is accessed;

an information file included in the discovery volume to indicate that at least a portion of the primary file system is encrypted; and

a pointer in the data structure pointing to at least one of;

an original boot block for the primary file system, the original boot block having been relocated from the boot sector to another portion of the primary file system;

or

a metadata data structure in the primary file system which points to a location of the original boot block.

16. The computer readable storage memory of claim 15, wherein the information file comprises a human readable information file providing further information regarding the primary file system.

17. The computer readable storage memory of claim 15, wherein the data structure further comprises one or more cover file entries in the discovery volume configured to appear to an accessing system to occupy portions of the computer readable storage media actually occupied by the primary file system.

18. The computer readable storage memory of claim 15, wherein a file system format of the discovery volume is file allocation table (FAT)12, or FAT16, or FAT32, or exFAT, or universal disk format (UDF), or new technology file system (NTFS), or second extended file system (ext2), or fourth extended file system (ext4), or Joliet file system, or Tux3 file system.

19. The computer readable storage memory of claim 15, wherein the data structure further comprises access software in the discovery volume, the access software enabling reading of the primary file system.

20. The computer readable storage memory of claim 15, wherein the original boot block for the primary file system is located within a metadata data structure on the computer readable storage media at a location other than at a beginning sector of the computer readable storage media.