VIRTUALIZED BOOT BLOCK WITH DISCOVERY VOLUME

• US 20100114990A1
• Filed: 10/24/2008
• Published: 05/06/2010
• Est. Priority Date: 10/24/2008
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Thind, Ravinder S., Ou-Yang, Darwin, Mehra, Karan, Moss, Darren G.
• Granted Patent: US 8,510,352 B2
• Time in Patent Office: Days
• US Class Current: 707/809
• 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 of rendering a volume visible across multiple accessing systems, the method comprising:

initializing a discovery volume;

initializing a boot block in the discovery volume;

moving the contents of one or more existing original boot blocks of a volume from a beginning of the volume to a new location in the volume or creating a boot block and writing the boot blocks in the volume at a location other than the beginning;

constructing one or more pointers in the boot block pointing to a data structure containing information referring to an original boot block for a primary file system; and

writing the one or more pointers to the boot block.

2. The method of claim 1, wherein the discovery volume is a FAT volume.

3. The method of claim 1, wherein the discovery volume contains one or more cover files.

4. The method of claim 1, further comprising:

returning contents of the original boot blocks when a read request comprising a boot block location is received.

5. The method of claim 1, further comprising:

redirecting a write request to a boot block to the original boot blocks such that the original boot block is written to and not the boot block at the beginning of the volume.

6. The method of claim 1, the method further comprising:

virtualizing the boot blocks concurrently at more than one level in an operating system.

7. The method of claim 1, wherein the data structure comprising information referring to the original boot blocks comprises a metadata data structure.

8. The method of claim 1, wherein the method is stored on a storage medium.

9. A method of utilizing a virtualized boot block, the method comprising:

reading a boot block in a volume;

following a pointer stored in the boot block pointing to a data structure comprising information referring to an original boot block;

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 blocks location to the location of the original boot block such that the contents of the original boot block are overwritten and not the data in at the boot blocks at the beginning of the volume.

10. The method of claim 9, wherein the boot block comprises a discovery volume boot block.

11. The method of claim 10, wherein the discovery volume comprises entries for cover files.

12. The method of claim 9, the method further comprising:

virtualizing the boot blocks concurrently at more than one level in an operating system.

13. The method of claim 9, the method further comprising:

mounting the volume in an operating system.

14. The method of claim 9, wherein the method is stored on a storage medium.

15. A computer readable storage media storing a data structure, the data structure comprising;

a data structure written in one or more boot blocks of a discovery volume; and

a pointer in the data structure pointing to one or more original boot block for a primary file system or a metadata data structure in the primary file system which points to the original boot block.

16. The data structure of claim 15, wherein the discovery volume further comprises a human readable information file.

17. The data structure of claim 15, further comprising:

one or more cover file entries in the discovery volume configured to claim space on the underlying real volume.

18. The data structure of claim 15, wherein the discovery volume is FAT 12, or FAT16, or FAT32, or exFAT, or UDF, or NTFS, or ext2, or ext4, or Joliet, or Tux3.

19. The data structure of claim 15, further comprising:

a file entry in the discovery volume, the file entry configured to claim a remainder of the volume or consume directory entry space.

20. The data structure of claim 15, wherein the original boot blocks for a volume is within a metadata data structure.