File integrity preservation

In one embodiment of file integrity preservation in accordance with the present description, a file is subdivided into a plurality of subfiles, and a write update originally targeted for a portion of that file contained within one of the subfiles, is instead directed to a temporary copy subfile. As a consequence, the temporary copy subfile which is updated with the write data, may be scanned for viruses or other malware separately from the original file and its corresponding original subfile. If the temporary copy subfile passes the scanning test, the originally targeted file may be updated with the updated contents of the clean temporary copy subfile. Conversely, in the event that the write update introduced malicious software to the temporary copy subfile, the original file and its corresponding original subfile remain uncontaminated by the write update. Other aspects are also described.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The subject matter disclosed herein relates to data updates to files and to anti-virus file scanning.

2. Description of the Related Art

Files are often scanned for computer viruses and other malicious software frequently referred to as “malware.” Such malicious software includes a variety of forms of hostile or intrusive software. Examples of malicious software include computer viruses, worms, trojan horses, and ransomware. Still other examples include spyware, adware, scareware, and other malicious programs. Malicious software can take the form of executable program code, scripts, active content, and other software. Malicious software is often disguised as, or embedded in, non-malicious files to facilitate the spread and to increase the difficulty in detecting the malicious software.

In some systems, upon a write operation to update a file, the write data is committed to the file to update the file, and an anti-virus scan is initiated on the updated file. Also in some systems, in order to facilitate the scanning process, a file to be scanned is subdivided into subfiles which are scanned separately by one or more scan servers. If the last write command introduces malicious software, the anti-virus scan can frequently detect it, and an attempt may be made to repair the infected file. If the repair of the infected file fails, the entire file is typically quarantined to prevent subsequent read operations to the infected file which can spread the malicious software. Hence, users are typically denied access to a quarantined file. However, a read operation directed to an infected file which has not been quarantined, may permit spread of the malicious software.

SUMMARY

Provided is a method for preserving file integrity in connection with a write operation to update a file, in which a temporary copy subfile corresponding to the originally targeted portion of the file, is created. Instead of committing the write update data to the originally targeted portion of the file, the write data is directed instead to update the temporary copy subfile. The updated temporary copy subfile may be scanned for malicious software, and if the updated temporary copy subfile passes the scan, the originally targeted portion of the file may be updated with the scanned update data contained by the temporary copy subfile which was determined to be free of malicious software.

In one embodiment, as a consequence of updating the temporary copy subfile instead of the original file, the temporary copy subfile after it has been updated with the write data, may optionally be scanned for viruses or other malware separately from the original file or its original subfile. Accordingly, in one embodiment, read access to the original file including the corresponding original subfile, may optionally be permitted while the temporary copy subfile is updated and scanned.

Conversely, in the event that the write update introduced malicious software to the temporary copy subfile, the original file and its corresponding original subfile remain uncontaminated by the write update. Accordingly, in one embodiment, access to the original file and its corresponding original subfile may optionally continue since they remain uncontaminated and their integrity has been preserved.

Still further, should the contaminated temporary copy subfile be quarantined, the original file and its corresponding original subfile may optionally remain free of quarantine since their integrity has been preserved. Accordingly, access to the original file and its corresponding original subfile may optionally continue since they remain uncontaminated and unquarantined.

In one embodiment, a location for the temporary copy subfile may optionally be obtained from a pool of available temporary subfile locations. In another embodiment, one or more attempts may optionally be made to repair the temporary copy subfile to eliminate the malicious software before the temporary copy subfile is quarantined. In another embodiment, the update data may optionally be resent one or more times to update one or more additional temporary copy subfiles instead of the original file.

Other embodiments are directed to systems, apparatus and computer program products. Still other aspects are described.

DETAILED DESCRIPTION

In one embodiment of file integrity preservation in accordance with the present description, a file is subdivided into a plurality of subfiles, and a write update originally targeted for a portion of that file contained within one of the subfiles, is instead directed to a temporary copy subfile. In this example, the temporary copy subfile contains a copy of the originally targeted subfile of the file and thus corresponds to the originally targeted subfile of the original file. As a consequence of updating the temporary copy subfile instead of the original file, the temporary copy subfile after it has been updated with the write data, may optionally be scanned for viruses or other malware separately from the original file or its original subfile. Accordingly, in one embodiment, read access to the original file including the corresponding original subfile, may optionally be permitted while the temporary copy subfile is updated and scanned.

In another aspect of the present description, if the temporary copy subfile passes the scanning test, the originally targeted file may be updated with the updated contents of the clean temporary copy subfile. Conversely, in the event that the write update introduced malicious software to the temporary copy subfile, the original file and its corresponding original subfile remain uncontaminated by the write update. Accordingly, access to the original file and its corresponding original subfile may optionally continue since they remain uncontaminated and their integrity has been preserved.

Thus, in those instances in which a read command is executed before a write update targeted for the same file has been completed and scanned for malicious software, spread of the malicious software may be avoided since the read operation may optionally be directed to the original file or subfile while the write update which may be carrying malicious software is directed to the temporary copy subfile. Accordingly, should the write update data be infected with malicious software, the read operation does not come into contact with the infected update data.

Still further, should the contaminated temporary copy subfile be quarantined, the original file and its corresponding original subfile may remain free of quarantine since their integrity has been preserved. Accordingly, access to the original file and its corresponding original subfile may optionally continue since they remain uncontaminated and unquarantined.

As used herein, the terms “scan”, “anti-virus (AV) scan” and anti-virus (AV) program” refer to scans and programs for detecting any malicious software including but not limited to computer viruses. The term “repair” refers to processing an infected file detected to be infected with malicious software, to eliminate or render harmless the malicious software. The term “quarantining” refers to restricting or completely blocking access to an infected file which has been quarantined to eliminate or inhibit the spread of the malicious software from the infected file.

FIG. 1is a schematic block diagram illustrating one embodiment of a data processing system100which provides for file integrity preservation in accordance with one embodiment of the present description. The system100includes a plurality of servers110as represented by the servers110a-110dthat may scan files or provide a host function, or both. In addition, the system100includes a network120and a storage system. The network120may be the Internet, a router, a wide area network, a local area network, or the like. The storage system includes a first bus125, a second bus150, and one or more storage servers130as represented by the servers130a,130b, which provide a data storage function in connection with one or more storage subsystems140as represented by the storage subsystems140a,140b,140c. In one embodiment, one or more servers110as represented by the servers110e,110fare included in the storage subsystem.

One or more servers as represented by the servers110a,110b, for example, may provide a host function to store data to and retrieve data from the storage system180. In some storage systems, an anti-virus (AV) program runs external to the servers performing the storage function. Thus, the anti-virus software can be run on one or more dedicated servers such as the servers110cand110d, for example which are external to the storage system180, or servers110e,110f, for example, which are internal to the storage system180, to validate that the data contained within a storage unit of the storage system180is virus free. To speed the scanning of files and to provide for continued use of files, particularly large files while they are being scanned, it is known to subdivide a file into subfiles and to distribute the scanning of the subfiles to different servers so that the various subfiles of a particular file may be scanned by different servers operating in parallel or at different times. In addition, subfiles of a file may be accessed while other subfiles of the file are being scanned.

Previously, a storage system typically provided real time scan “on write” operations. For example, in connection with a write operation, the write data provided by a host server110a,110bwas previously committed directly to the targeted file, and an AV Scan was initiated on the updated targeted file in which typically the entire file was scanned after the write operation. If the last write command introduced malicious software, and the AV Scan detected it, a repair of the infected file was attempted. If the repair of the infected file failed, the infected file was typically quarantined, blocking access to the quarantined file. In some prior systems, an entire file which may be a terabyte in size or larger, may be quarantined notwithstanding that only a relatively small portion of the file is actually infected.

As previously mentioned, in accordance with one aspect of the present description, file integrity may be preserved by subdividing a file into a plurality of subfiles, and directing a write update intended for a portion of that file to a temporary copy subfile instead. The temporary copy subfile is a copy of the original portion of the file which was the target of the write operation. As a result, malicious software if contained within the write update data would contaminate the temporary copy subfile rather than the original targeted file or its subfiles. In this manner, quarantining of either the original file or its original subfile may be avoided.

In addition, it is recognized herein that previously an anti-virus scan may have been insufficient to protect a file in the event that a “read” operation and a “write” operation occurred at the same time. For example, in many prior systems, an AV Scan had typically been initiated only on an “open for read” operation or a “close after a write” operation. Accordingly, an AV Scan was frequently not initiated on every read operation. As a result, if a process opened a file for a read operation while another process was writing to the same file and the write operation introduced malicious software, the read process in a prior storage system might have read that introduced virus before the AV scan and any subsequent repair or quarantine were completed.

As previously mentioned, in accordance with one aspect of the present description, file integrity may be preserved by subdividing a file into a plurality of subfiles, and directing a write update originally targeting a portion of that file to a temporary copy subfile instead to the original file itself or its subfile. Accordingly if a process opens a file for a read operation while another process is writing infected data which had been originally targeted for the same file, as a result of file integrity preservation in accordance with the present description, the read process would not encounter that malicious software in the original file or its subfiles since any malicious software would be introduced to the temporary copy subfile rather than to the original file which is being read.

Each storage subsystem140ofFIG. 1may include one or more controllers160that control one or more storage devices170. The storage devices170may be hard disk drives, optical storage devices, micromechanical storage devices, semiconductor storage devices, and the like. Storage servers130may manage and control the storage system180. The storage servers130may communicate with the network120and the storage subsystems140through the first bus125and second bus150respectively.

The storage devices170may store files, directory information, metadata, and the like, referred to hereafter as files. The servers110e,110fmay scan the files for the purpose of detecting and mitigating any malware that may be stored in a file. The servers110may be external to the storage system180and/or internal to the storage system180as described above.

Files in the storage system180can grow to various sizes; very small to very large file sizes can exist. Scanning such large files with a single server110in some systems may require an inordinate amount of time. In addition, a large file that is being scanned may be inaccessible during the long scan time. Having a file inaccessible for such a long period of time is burdensome for important files. As previously mentioned, to speed the scanning of files and to provide for continued use of files, particularly large files, it has been known to subdivide a file into subfiles and to distribute the scanning of the subfiles to different servers so that the various subfiles of a particular file may be scanned by different servers operating in parallel or at different times.

FIG. 2is a schematic block diagram illustrating one embodiment of a file200, the integrity of which may be preserved in accordance with the present description. The file200may be stored in the storage system180ofFIG. 1, for example. As previously mentioned, a file such as the file200may be quite large. For example, in one embodiment, the file200may have a size in excess of 1 Terabyte (TB). Here, the file200is divided into a plurality of subfiles205as represented by the subfiles205a,205b,205c,205d. . . . In one embodiment, each subfile205is no larger than a specified size. The specified size may vary in range, such as 1 Megabyte (MB) to 1 Gigabyte (GB), for example. In another example, the file200may be divided so that each subfile205is no larger than a specified size of 10 GB. It is appreciated that the size of a subfile may vary, depending upon the particular application. This subdivision process may be initiated multiple times until the entire file scan is completed by the prior subdivided file scanning procedure.

In accordance with one aspect of the present description, division of files into subfiles may be utilized for preservation of file integrity by redirecting a write update targeting, that is intended for, a portion of a particular file, to a temporary copy subfile containing a copy of the targeted portion of the original file.FIG. 3shows an example of such file integrity preservation in connection with a write update operation for write update data sent by a host server such as the host server110a. The write update data from the host server110atargets data contained within a subfile205bof the file200. Instead of immediately committing the write update data to the targeted original subfile205bof the file200, a first temporary copy subfile205b1corresponding to the first original subfile205bis created and the contents of the original subfile205bare copied over to the temporary copy subfile205b1.

In one embodiment, a temporary copy subfile such as the temporary copy subfile205b1(FIG. 3) may be created by obtaining a temporary memory location for the particular temporary copy subfile from a pool210(FIG. 4) of available temporary locations210a,210b,210c. . . . In this example, the pool of available temporary locations210a,210b,210care provided by disk drive storage locations. However, it is appreciated that in other embodiments, the pool of available temporary locations210a,210b,210cmay be provided by volatile or nonvolatile memory or by storage locations provided by other types of storage devices, depending upon the particular application.

In one embodiment, file integrity preservation in accordance with the present description may be invoked with a command line interface (CLI) command having a suitable name such as “Preserve File Integrity on Write” for example. Upon invoking this command, to enable the file integrity preservation process for a particular file such as the file200, the file integrity preservation process creates storage space as represented by pool210(FIG. 4) of available temporary locations210a,210b,210c. . . using a storage controller160and the storage devices170to contain temporary copy subfiles for the file200. In one embodiment, the size of the pool210may be dependent upon the size of the file200for which the file integrity preservation command was invoked, and the frequency of write updates to the file200. It is appreciated that the size of the pool210may vary, depending upon the particular application.

In this example, the temporary copy subfile205b1is created using an available temporary copy subfile location210bof the pool210of available temporary locations. Accordingly a data structure for the temporary copy subfile205b1has a file location pointer (as represented by an arrow212a) pointing to the temporary copy subfile location210bof the pool210of available temporary locations, as the location of the temporary copy subfile205b1. The contents of the targeted original subfile205bare copied over to the location of the temporary copy subfile205b1so that the temporary copy subfile205b1corresponds to the targeted original subfile205b.

When a host sends a “write command” to update a file, and the CLI command “Preserve File Integrity on Write” is enabled on the file, the write data associated with the “write command” is committed to the temporary copy subfile in the storage location instead of the original file. Thus, in this example, once the temporary copy subfile205b1corresponding to the targeted original subfile205bis available, the write update data received for the write operation and intended for the original subfile205b, is committed to update the temporary copy subfile205b1as indicated by the Write Data Update process arrow ofFIG. 3, instead of being committed to update the original subfile205b. As a consequence, the temporary copy subfile205b1which is updated with the write data, may be scanned for malicious software as indicated by the Anti-Virus Scan process arrow ofFIG. 3, separately from the original file200and its corresponding original subfile205b. Accordingly, in one embodiment, access to the original file200including the corresponding original subfile205b, may be permitted while the temporary copy subfile205b1is updated and scanned.

If the temporary copy subfile205b1passes the scanning test, the original file200may be updated with the scanned and updated contents of the clean temporary copy subfile205b1as indicated by the Scanned Write Data Update If not Infected process arrow ofFIG. 5. In one embodiment, the original file200may be updated by copying the scanned, updated contents from the temporary location210b(FIG. 4) of the temporary copy subfile205b1to the location of the targeted original subfile205b. Upon successful updating of the original file200with the scanned, updated contents of the temporary copy subfile205b1, the temporary memory or storage space utilized by the temporary copy subfile205bmay be released for use by other processes. Thus, the temporary copy subfile location210bmay be released and returned to the pool210of temporary copy subfile locations.

Another example of a technique for updating the original file200with the scanned, updated contents of the temporary copy subfile205b1is referred to herein as a switch subfile pointer process and is described in connection withFIG. 6below. It is appreciated that the original file200may be updated with clean update data from the temporary copy subfile205b1using other techniques, depending upon the particular application.

As previously mentioned in connection withFIG. 4, the temporary copy subfile205b1has a file location pointer (as represented by an arrow212a) pointing to the temporary copy subfile location210bof the pool210of available temporary locations, as the location of the temporary copy subfile205b1. Similarly, the targeted original subfile205bhas a file location pointer (as represented by an arrow212b) pointing to the original subfile location within the file200, as the location of the targeted original subfile205b. Instead of copying the data of the updated and scanned temporary subfile205b1from the temporary copy subfile location210bof the pool to the targeted original subfile205bat its original location within the file200, the file pointers of the temporary copy subfile205b1and the targeted original subfile205bmay be updated by switching them as depicted inFIG. 6.

Once switched, the targeted original subfile205bhas a file location pointer (as represented by an arrow212c) pointing to the temporary copy subfile location210bof the pool210of available temporary locations, as the location of the targeted original subfile205b, since the temporary copy subfile location210bcontained the updated data which has been scanned and confirmed as free from malicious software as described above. In this manner, the targeted original subfile205bof the file200may be updated with the scanned write update data without actually copying it from the temporary copy subfile205b1to the original subfile205b. Similarly, once switched, the temporary copy subfile205b1has a file location pointer (as represented by an arrow212dpointing to the original subfile location within the file200, as the location of the temporary subfile205b1. This location may now be released to the pool210of temporary copy subfile locations.

In this manner, updating the original targeted subfile205bwith the updated and scanned contents of the temporary copy subfile205b1includes updating a file pointer for the original targeted subfile205bto identify the temporary copy subfile location210bof the temporary copy subfile205b1as the location of original targeted subfile205binstead of identifying the original location within the file200as the location of the original targeted subfile205b. Furthermore, updating the pool pointer for the temporary copy subfile205b1to identify the location of the temporary copy subfile205b1as the original location targeted subfile205bwithin the file200instead of identifying the original temporary copy subfile location210bof the temporary copy subfile205b1. In some embodiments, updating file pointers in accordance with the process described herein may be achieved more quickly and efficiently as compared to copying the scanned updated data from the temporary copy subfile to the original subfile.

Conversely, in the event that the AV scan reveals that the write update introduced malicious software to the temporary copy subfile205b1, the original file200and its corresponding targeted original subfile205bremain uncontaminated by the write update. Accordingly, access to the original file200and its corresponding original subfile205bmay continue since they remain uncontaminated and their integrity has been preserved.

An attempt may be made to repair the infected temporary copy subfile205b1as indicated by the Attempt Repair if Infected process arrow ofFIG. 3. The temporary copy subfile205b1which had been updated with the write data, may be rescanned for malicious software following the repair attempt as represented by the Anti-Virus Scan process arrow ofFIG. 3, again separately from the original file200and its corresponding original subfile205b.

If the repaired temporary copy subfile205b1passes the rescanning test, the original file200may be updated with the rescanned and updated contents of the clean temporary copy subfile205b1as indicated by the Scanned Write Data Update If not Infected process arrow ofFIG. 5using update techniques such as those described above. Conversely, in the event that the AV rescan reveals that the repair of the temporary copy subfile205b1failed such that the temporary copy subfile205b1remains contaminated from the write update, the temporary copy subfile205b1may be quarantined as represented inFIG. 7. As a result, the storage space210b(FIG. 4) occupied by the quarantined temporary subfile205b1is marked unavailable for use. It is appreciated that the number of repair attempts and failed rescans before the temporary copy subfile is quarantined may vary, depending upon the particular application.

Still further, should the contaminated temporary copy subfile205b1be quarantined, the original file200and its corresponding original subfile205bmay remain free of quarantine as shown inFIG. 7since their integrity has been preserved because the subfile205b1in the temporary location is in a quarantined state and has not been committed to a location within the file200. Accordingly, access to the original file200and its corresponding original subfile205b1continues since they remain uncontaminated and unquarantined.

However, upon quarantining the temporary copy subfile205b1, the file200will not contain the latest updates represented by the quarantined write update data. In one embodiment, the original host server110awhich provided the original write update data may be requested to resend the write update data. In another aspect of the present description, in the event that the first temporary copy subfile205b1is quarantined, a second temporary copy subfile as represented by the temporary copy subfile205b2(FIG. 8) may be created. In one embodiment, a second temporary copy subfile such as the temporary copy subfile205b2(FIG. 8) may be created by obtaining a temporary storage location in a manner similar to that described above in connection with temporary copy subfile205b1. In this example, the temporary copy subfile205b2is created using an available temporary copy subfile location210dof the pool210of available temporary locations. Accordingly a data structure for the temporary copy subfile205b2has a file location pointer (as represented by an arrow212e) pointing to the temporary copy subfile location210dof the pool210of available temporary locations, as the location of the temporary copy subfile205b2. The contents of the targeted original subfile205bare copied over to the location of the temporary copy subfile205b2so that the temporary copy subfile205b2corresponds to the targeted original subfile205bin the same manner as the first temporary copy subfile205b1.

Once the temporary copy subfile205b2corresponding to the targeted original subfile205bis available, the write update data resent by the original host server110afor the write operation intended for the original subfile205b, is committed to update the temporary copy subfile205b2in the same manner as described above in connection with temporary copy subfile205b1. Accordingly, the temporary copy subfile205b2which is updated with the write data, may be scanned for malicious software in the same manner as described above in connection with temporary copy subfile205b1.

If the temporary copy subfile205b2passes the scanning test, the original file200may be updated with the scanned and updated contents of the clean temporary copy subfile205b2in the manner described above in connection with temporary copy subfile205b1. Upon successful updating of the original file200with the scanned, updated contents of the temporary copy subfile205b2, the temporary memory or storage space utilized by the temporary copy subfile205b2may be released and returned to the pool210of temporary copy subfile locations.

Conversely, in the event that the AV scan reveals that the resent write update again introduced malicious software, this time to the temporary copy subfile205b2, an attempt may be made to repair and rescan the infected temporary copy subfile205b1one or more times as described above in connection with temporary copy subfile205b1. If the write update data that was resent is once again quarantined, then the file200may be marked with a suitable indication such as “not up to date,” for example, to indicate that the particular file area (in this example, subfile205b) was not updated. In this example, the user may also be informed that the particular file area (in this example, subfile205b) was not updated, and that the temporary copy subfiles205b1and205b2have been quarantined. In addition, the original host server (host server110ain this example) may be requested to not resend the particular write update data which was found to contain malicious software and which could not be repaired as discussed above. Further in one embodiment, any subsequent write updates from the same host (host server110ain this example) to the same subfile (in this example, subfile205b) may be rejected.

In another aspect of the present description, once the user has been informed that subfile205bhas not been updated and has been informed of the quarantining of the temporary copy subfiles205b1,205b2, the user may select to delete the quarantined subfile data of the quarantined subfiles205b1,205b2. If so, the infected storage locations210b,210dare cleared, and another AV Scan is performed on those areas. If a storage location which previously contained a quarantined temporary copy subfile is found to be free of malicious software, the storage location may be returned to the pool210of temporary storage locations. In addition, in one embodiment, the subsequent write updates from the same host (host server110ain this example) to the previously subfile205bfor which temporary copy subfiles205b1,205b2were quarantined, may be accepted.

It is seen from the above that a host that sends an “open read” command for the file receives the file data that is virus free. As previously stated, the host will be notified that the file contains an area (subfile in this example) that did not get updated due to a virus detection. As in current art, since the file was not updated, an “open read” command from a host will not cause an AV scan if the AV scan engines have not been updated with new AV software.

As previously mentioned, upon quarantining the first temporary copy subfile205b1, the file200will not contain the latest updates represented by the quarantined write update data. In another embodiment, the original host server110awhich provided the original write update data may be requested to not send write update data to the subfile205b. Instead, a second host such as the host server110b, for example, may be requested to provide the write update data targeted to update the subfile205b. In this example, the write update data provided by the second host server110bmay be the same as that provided by the first host server110a, but may be free of malicious software.

Accordingly, in this example, in the event that the first temporary copy subfile205b1is quarantined, a second temporary copy subfile as represented by the temporary copy subfile205b2(FIG. 8) may be created to receive the write update data from the second host server110bin a manner similar to that described above in connection with the first host server110a. If the temporary copy subfile205b2containing the write update data from the second host server110bpasses the scanning test, the original file200may be updated with the scanned and updated contents of the clean temporary copy subfile205b2in the manner described above in connection with temporary copy subfile205b1. Upon successful updating of the original file200with the scanned, updated contents of the temporary copy subfile205b2, the temporary memory or storage space utilized by the temporary copy subfile205b2may be released and returned to the pool210of temporary copy subfile locations. In addition, the first host server110amay be permitted to resume sending subsequent write updates targeted for the subfile205b.

Conversely if the write update data that was sent by the second host server110bis also quarantined, then the file200may be marked with a suitable indication such as “not up to date,” for example, to indicate the particular file area (in this example, subfile205b) which was not updated. In this example, the user may also be informed that the particular file area (in this example, subfile205b) was not updated, and that the temporary copy subfiles205b1and205b2have been quarantined. In addition, the second host server (host server110bin this example) may be requested to not resend the particular write update data which was found to contain malicious software and which could not be repaired as discussed above. Further in one embodiment, any subsequent write updates from the same host (host server110bin this example) to the same subfile (in this example, subfile205b) may be rejected.

In another aspect of the present description, once the user has been informed that subfile205bhas not been updated and has been informed of the quarantining of the temporary copy subfiles205b1,205b2, the user may in this example as well select to delete the quarantined subfile data of the quarantined subfiles205b1,205b2. If so, the infected storage locations210b,210dare cleared, and another AV Scan is performed on those areas. If a storage location which previously contained a quarantined temporary copy subfile is found to be free of malicious software, the storage location may be returned to the pool210of temporary storage locations. In addition, in one embodiment, the subsequent write updates from the same hosts (host servers110a,110bin this example) targeted for the subfile205bfor which temporary copy subfiles205b1,205b2were quarantined, would be accepted.

In one embodiment, the size of each subfile205may be selected to be proportional to the capacity of a server110scanning the subfiles such as the original subfile205band its corresponding temporary copy subfiles205b1,205b2, for example. The size may be fixed or may be dynamically assigned. It is appreciated that other sizes and other techniques for choosing the sizes of the subfiles may be utilized depending upon the particular application.

FIG. 9is a schematic block diagram illustrating one embodiment of an anti-virus control file302. The anti-virus control file302includes an entry220for each subfile original or temporary to be scanned. In one embodiment, each entry220includes a status230, a server identifier235, and a subfile address240.

The status230may be selected from the group consisting of in-queue, quarantined, and cleared statuses. The in-queue status may indicate that an original or temporary copy subfile205is scheduled to be scanned by a server110, but has not been found to be clear of malicious software. In one embodiment, subfiles205within the in-queue status may be accessed. Alternatively, subfiles205with the in-queue status may not be accessed. As used herein, accessed refers to a subfile205being read from and/or written to by an application, an operating system, or the like.

The quarantined status may indicate that malicious software has been found in the subfile205. In one embodiment, subfiles205with a quarantined status may not be accessed. Subfiles205with the quarantined status may be scheduled for mitigation, deletion or other processing. The mitigation may include repair to delete malicious software from the subfile205, overwriting the subfile205with a backup copy, and rebuilding the subfile205using error codes and/or redundant data, and the like.

The cleared status may indicate that the subfile205has been scanned and that no malicious software has been found. In one embodiment, subfiles205with a cleared status may be accessed. For example, if the first subfile205aof a large database file200has been scanned and has a cleared status, the first subfile205amay be accessed.

The server identifier235may identify the server110assigned to scan the subfile205. In one embodiment, the server identifier235is a network address. Alternatively, the server identify235may be a logical name.

The subfile address240may include a start address and an end address for the subfile250. In one embodiment, the subfile address240includes start addresses and end addresses for a plurality of segments that make up the subfile.

FIG. 10is a schematic block diagram illustrating one embodiment of a computer300. The computer300may be the server110. Alternatively, the computer300may be a storage server130, a controller160, or the like. The computer300may include a processor305, a memory310, and communication hardware315. The memory310may be a semiconductor storage device, a hard disk drive, or the combinations thereof. The memory310may store computer readable program code. The processor305may execute the computer readable program code. The computer300may communicate with the external devices through the communication hardware315.

FIG. 11is a schematic block diagram illustrating one embodiment of a file integrity preservation apparatus350. The apparatus350may be embodied in the computer300. The apparatus350includes an anti-virus control file320, a division module325, an access module330and a subfile update module360.

In one embodiment. the anti-virus control file320, the division module325, the access module330and the subfile update module360may be embodied in a computer-readable storage medium storing computer readable program code. The computer readable storage medium may be the memory310. The processor305may execute the computer readable program code to perform the functions of the anti-virus control file320, the division module325, the access module330and the subfile update module360

The division module325may divide the file200into a plurality of subfiles205and create the temporary copy subfiles. The access module330may maintain a status of each subfile205. In addition, the access module330may scan each subfile205with a separate server110as described herein. If the subfile passes the scan, the subfile update module360may update the subfile with the scanned update data.

FIG. 12shows one embodiment of operations for file integrity preservation in accordance with the present description. Upon the initiation of a write data update (block400) in which a host provides write data targeted to update a portion of a file, the write data update is instead used to update (block404) a temporary copy subfile corresponding to a subfile of the file containing the targeted portion of the write data operation. Upon updating the temporary copy subfile of the file with the write update, the updated temporary copy subfile is scanned (block408) for malicious software. If the scanned, updated temporary copy subfile passes (block412) the scan, the file or its original subfile may be updated (block416) with the scanned, updated contents of the temporary copy subfile. In addition, any blocks applied to prior sources of infected write data for the subfile of the file may be removed (block420) to permit resumption of access to the subfile for the previously blocked sources.

Conversely, if the updated, scanned temporary copy subfile fails (block412) the scan such that the temporary copy subfile was found to be infected with malicious software, an attempt (block434) may optionally be made to repair the scanned, updated temporary copy subfile found to be infected with malicious software. Upon completion of the repair attempt, the temporary copy subfile may be rescanned (block436) to determine if the repair attempt was successful. If the temporary copy subfile fails the scan again, that is, the repair attempt was unsuccessful (block436), the temporary copy subfile may be quarantined (block440). In one embodiment, a determination may be made (block448) as to whether to request a resending of the write update data. The request to resend the write update data may be made to the original source of the write update data or to a different source. If a resending of the write update data is requested and received, the resent write update data may be used to update (block404) another temporary copy subfile and the operations of blocks404-448may be repeated.

If it is determined (block448) that the resending of the write update data is not to be requested, the source of the infected write update data may be temporarily blocked (block450) from further access to the subfile which was targeted by the write data update. In one embodiment, further operations may be performed as explained in greater detail in connection withFIG. 13below.

If the repair attempt (block434) allows the updated temporary copy subfile to pass (block436) the scan, indicating that the repair was successful, the file or its original subfile may be updated (block416) with the scanned, updated contents of the temporary copy subfile. In addition, any blocks applied to prior sources of infected write data for the subfile of the file may be removed (block420) to permit resumption of access to the subfile for the previously blocked sources.

As previously mentioned, if a determination (block448) is made to request no further resends of the write update data, a further operations may optionally be performed.FIG. 13depicts one example of operations which may be initiated (block500) subsequent to quarantining (block440,FIG. 12) a temporary copy subfile. In one embodiment, further operations may include deleting (block504) the contents of the quarantined temporary copy subfiles and scanning (block508) the locations of the deleted temporary copy subfiles to ensure that they are free of malicious software. If so, the locations of the temporary copy subfiles may be returned (block516) to a pool of temporary copy subfiles for use by other processes. Alternatively, if the scanning (block508) of the locations of the deleted temporary copy subfile indicates that malicious software remains, the quarantining of the locations of the temporary copy subfile may continue (block520). In some embodiments, one or more additional attempts may be made to clean the temporary copy subfile locations found to harbor malicious software.

As previously mentioned in connection withFIG. 12, in the event that a temporary copy subfile is quarantined (block440,FIG. 12), a determination may be made (block448) as to whether to request a resending of the write update data.FIG. 14is directed to an embodiment in which the request to resend the write update data is made to a source other than the original source of the write update data.

In this embodiment, the resent write update data from the second source may be used to update (block404,FIG. 12) another temporary copy subfile instead of the original targeted subfile205b(FIG. 8) of the original file200and the operations of blocks404-448(FIG. 12) may be repeated with respect to the second temporary copy subfile. Accordingly, upon receipt (block600) of the resent write update data from a second host, the resent update data intended to update the subfile205b, is instead used to update (block604) a second temporary copy subfile205b2corresponding to the subfile205bof the file200containing the targeted portion of the write data operation. Upon updating the second temporary copy subfile of the file with the write update, the updated second temporary copy subfile is scanned (block608) for malicious software. If the scanned, updated second temporary copy subfile passes (block612) the scan, the file200or its original subfile205bmay be updated (block616) with the scanned, updated contents of the second temporary copy subfile. In addition, any blocks applied to prior sources such as the original source of the infected write data for the subfile of the file may be removed (block620) to permit resumption of access to the subfile for the previously blocked sources.

Conversely, if the updated, scanned second temporary copy subfile205b2fails (block612) the scan such that the second temporary copy subfile was found to be infected with malicious software, an attempt (block634) may be made to repair the scanned, updated second temporary copy subfile found to be infected with malicious software. Upon completion of the repair attempt, the second temporary copy subfile may be rescanned (block636) to determine if the repair attempt was successful. If the second temporary copy subfile fails the scan again, that is, the repair attempt was unsuccessful (block636), the second temporary copy subfile may be quarantined (block640). In one embodiment, a determination may be made (block448) as to whether to request a resending of the write update data from the second source or another source. If a resending of the write update data is requested and received, the resent write update data may be used to update (block604) another (such as a third) temporary copy subfile and the operations of blocks604-648may be repeated.

If it is determined (block648) that the resending of the write update data is not to be requested again, the second source of the infected write update data may be temporarily blocked (block650) from further access to the subfile which was targeted by the write data update. In one embodiment, further operations may be performed for the quarantined second temporary copy subfile as explained in greater detail in connection withFIG. 13above.

If the repair attempt (block634) allows the updated second temporary copy subfile to pass (block636) the scan, indicating that the repair was successful, the file200or its original subfile205bmay be updated (block616) with the scanned, updated contents of the second temporary copy subfile. In addition, any blocks applied to prior sources of infected write data for the subfile of the file may be removed (block620) to permit resumption of access to the subfile for the previously blocked sources.