File system implementing write once read many (WORM)

Patent metadata

Field	Value
Publication number	US-9659028-B2
Application number	US-201414491208-A
Country	US
Kind code	B2
Filing date	Sep 19, 2014
Priority date	Oct 24, 2013
Publication date	May 23, 2017
Grant date	May 23, 2017

Abstract

The embodiments deal with files that are already present in a storage when mounting the storage in a file system and files created after the mounting as different groups. (Metadata of) the files is classified. The files are each divided into metadata (index) and a file main body and are recorded on different storage areas, that is, an index partition (IP) and a data partition (DP), associated with each other. This file system is effective in a storage format in which a new file is merely written and an already written file is not updated or deleted (for example, a tape medium used in the LTFS). The embodiments implement a WORM file system by rejecting a request to update or delete a file that is present at mounting as a WORM file and permitting update or deletion of a file that is created after mounting until the storage is unmounted.

First claim

The invention claimed is:

1. A data processing system comprising:
a storage device, wherein the storage device stores computer usable program code; and
a processor, wherein the processor executes the computer usable program code, and wherein the computer usable program code comprises:
computer usable code for a file system, the file system classifying files in a mounted storage in a storage format in which the files are each divided into metadata and a file main body and are recorded in association with each other, and in which a new file is merely written, and an already written file is not updated or deleted, wherein the file system when executing on the data processing system performs operations comprising:

making a first determination whether a file present in the mounted storage has already been present in the storage when the storage is mounted;
classifying, responsive to the first determination being affirmative, the file as belonging to a first group as a Write-Once-Read-Many (WORM) file;
rejecting, responsive to the file belonging to the first group, at least one of an update and a deletion of the file;
classifying, responsive to the first determination being negative, when the file is written after the mounting, the file as belonging to a second group as a Read/Write (R/W) file;
permitting, responsive to the file belonging to the second group, at least one of the update and the deletion of the file;
making a second determination, when the mounted storage is accessed from outside the data processing system, that an access target belongs to the first group, the access target including the file; and
rejecting by the file system, responsive to the second determination, at least one of the update and the deletion of the file;
making a third determination, when the mounted storage is accessed from outside the data processing system, that an access target belongs to the second group, the access target including the file; and
permitting by the file system, responsive to the third determination, at least one of the update and the deletion of the file.

2. The data processing system comprising the file system according to claim 1 , further comprising:
returning from the file system, responsive to the rejecting the at least one of the update and the deletion of the file, an error in response to the access from the outside.

3. The data processing system comprising the file system according to claim 1 , wherein
the mounted storage is a tape medium; and
the computer usable code for the file system further comprises computer usable code for a table that stores a result of the classifying as the first group and a result of the classifying as the second group.

4. The data processing system of claim 1 , wherein the classifying responsive to the first determination being negative comprises classifying the metadata of the file, and the at least one of the update and the deletion of the file comprises at least one of an update and a deletion of the metadata of the file.

5. A computer readable article of manufacture tangibly embodying computer readable instructions which, when executed, cause a computer to carry out steps of a method for operating a file system comprising a table in which a plurality of files in a mounted storage are classified, and in which a new file is merely written, and an already written file is not updated or deleted, the method comprising:
dividing, using a storage format of the storage, each file in the plurality of files is divided into metadata and a file main body;
recording, in the storage, the metadata and the file main body in association with each other;
making a first determination relative to a file, whether the file has already been present in the storage when the storage is mounted;
classifying, responsive to the firsts determination being affirmative, the file under a first group as a Write-Once-Read-Many (WORM) file;
rejecting, responsive to the file belonging to the first group, at least one of an update and a deletion of the file;
classifying, responsive to the first determination being negative, when the file is written after the mounting, under a second group as a Read/Write (R/W) file;
permitting, responsive to the file belonging to the second group, at least one of the update and the deletion of the file;
storing the table as two data structures in a memory connected to the file system;
making a second determination, when the mounted storage is accessed from outside the data processing system, that an access target belongs to the first group, the access target including the file; and
rejecting by the file system, responsive to the second determination, at least one of the update and the deletion of the file;
making a third determination, when the mounted storage is accessed from outside the data processing system, that an access target belongs to the second group, the access target including the file; and
permitting by the file system, responsive to the third determination, at least one of the update and the deletion of the file.

6. The computer readable article of manufacture tangibly embodying computer readable instructions which, when executed, cause the computer to carry out further steps of the method for operating the table according to claim 5 , wherein
the table is a hash table.

Assignees

• IBM

Inventors

• Abe Atsushi
• Ashida Takashi
• Ishimoto Takeshi
• Masuda Setsuko
• Oishi Yutaka
• Washizawa Masahide
• Watanabe Terue

Classifications

• G06F16/116

  Details of conversion of file system types or formats · CPC title

• G06F16/181 Primary

  providing write once read many [WORM] semantics · CPC title

• G06F21/00

  Security arrangements for protecting computers, components thereof, programs or data against unauthorised activity · CPC title

• G06F17/30076

  Physics · mapped topic

• G06F17/30188 Primary

  Physics · mapped topic