Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02279759 1999-07-30
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DRIVE NAMES
Field of the Invention
The invention relates generally to mass storage devices and more particularly
to a
method of using mass storage devices with graphical user interfaces and remote
access
type applications.
Background of the Invention
In the early days of computers, operating systems provided few file system
tools.
Of course, since most early computer systems supported only a small number of
storage
devices, manual searching for a particular file was not uncommon or onerous.
For
example, to locate a particular file, one would know the identifier for a
device - A: in MS
DOS~ - and based on the identifier, one could request a directory listing.
Listing of each
available device, A:, B:, C:, D:, etc. was done until there were no more
devices or the
desired file was found.
Because the above method has an efficiency relating to the size and number of
devices, tools were developed to automatically catalogue contents of a disk
for a user to
peruse. These tools would provide a single listing of all files that could be
sorted or
searched by a user.
With the proliferation of the graphical user interface, tools such as find
file and
file management utilities have become the norm. These tools are very valuable
tools for
day to day use of computer systems. Unfortunately, when a computer has a large
number
of devices attached thereto, these tools require extensive amounts of system
resources in
order to manage the devices. Also, when the devices are removable, it is
common that the
tools cannot recognise that the device is or is not present at a given moment.
Conventional operating systems change a file access path to a removable media
when the media is moved from one drive, device and/or PC to another.
Unfortunately,
with removable media, it is quite difficult to ensure that a removable medium
is always
returned to a same device. Since removable media are often removed - replaced
by other
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removable media - when they are needed again, the replacement media may still
be
required and a different device is therefore used.
When media is moved from one drive to another, its file access path changes.
In a
volatile environment, where devices are swapped frequently, the file access
path changes
frequently. Thus, to access a same file requires different identifiers each
time the media is
replaced in a different device. However, many applications store complete
paths and
expect this path will not change. If such as application looks for a file and
the device
identifier in the form of a drive letter for Windows NT~, has changed, it will
not be able
to locate the file.
Also, with the proliferation of broadband communications, it has become
common that access to a computer system is provided to a larger base of users.
The
Internet is a commonly available example of this. On the Internet, there are
sites devoted
to information dissemination. Some of these sites have a considerable amount
of
proprietary information. In order to provide users access to information
within a site, two
methods are commonly employed. First, the information is stored in a public
directory,
which can be accessed by anyone. This is effective when copying of the
information is
expected. A user accessing the site can copy the entire contents of the site
to his or her
own storage medium. Obviously, this is not always desired. A second common
method is
to use a software program to retrieve the information and provide it to the
users.
Commonly, the data accessed by the software application is also accessible to
the users.
Therefore, once again, the data can be found and copied.
It would be advantageous to provide a method of storing publicly accessible
data
that is difficult or impossible to access absent the use of a software
interface provided at
or by the information source.
In order to overcome these and other limitations of the prior art, it is an
object of
the present invention to provide a method of storing immediately accessible
data that is
not recognised by the system tools within a Windows NT~ system.
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Summary of the Invention
In accordance with the invention there is provided a method of accessing a
removable
storage medium from a computer system in execution of an operating system
having a
plurality of file system commands and at least a file system tool, the method
comprising
the steps of:
providing a removable storage medium;
mounting the removable storage medium such that it is accessible through some
file
system commands but innaccessible through a file system tool from the file
system tools;
and,
performing at least one of storing data to and retrieving data from the
removable storage
medium while it is mounted.
In accordance with the invention there is further provided a method of storing
data from a
computer system to a removable storage medium comprising the steps o~
mounting the removable storage medium on the computer system, the removable
storage
medium mounted with an identifier recognisable by the file system but
unrecognisable by
the system tools;
storing data using the identifier, the data stored within the removable
storage medium.
In accordance with the invention there is also provided a method of accessing
a
removable storage medium from a computer system in execution of an operating
system
having a plurality of file system commands and at least a file system tool.
The method
comprises the following steps:
providing a removable storage medium; and,
mounting the removable storage medium. The step of mounting the storage medium
comprises the following steps:
when a newly inserted removable storage medium is detected, reading from the
removable storage medium an identifier
determining a presence of a symbolic link for the identifier;
when a symbolic link exists, updating the symbolic link to reflect the
physical
path to the storage medium;
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when the symbolic link does not exist, creating a symbolic link from the
identifier
to the storage medium, the symbolic link to a non-standard storage medium;
and,
performing at least one of storing data to and retrieving data from the
removable
storage medium while it is mounted.
Brief Description of the Drawings
The invention will now be described with reference to the attached drawings in
which:
Fig. 1 is a simplified diagram of a hardware system incorporating several
removable
media devices;
Fig. 2 is a simplified diagram of a symbolic link;
Fig. 3 is a simplified flow diagram of a method of accessing a storage device
according to
the invention;
Fig. 4 is a simplified flow diagram of a method of accessing a storage device
according to
the invention using an identifier unique to the storage medium; and,
Fig. 5 is a simplified flow diagram of a method of accessing a storage device
according to
the invention using symbolic links identified by an identifier determined from
the storage
medium.
Detailed Description of the Invention
According to the present invention a device is assigned a device name that is
unrecognisable to system utilities. In such a fashion, the devices are
inaccessible to
anyone who does not know an identifier in the form of a path name. Also, the
device is
not listed on the desktop or with a list of accessible storage media for use
with a graphical
user interface (GUI). For example, in Windows NT~ Disk Administrator, the
identifiers
do not appear. This allows mounted storage media to appear as if they are not
mounted
and therefore to be hidden from view or access. In accordance with the
preferred
embodiment described below, the identifiers are specific to a medium and as
such do not
change when the medium is moved to a different device.
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Referring to Fig. 1, a computer system 1 is shown comprising a monitor 3, a
processor 4 and four removable media drives in the form of read/write optical
disk drives
Sa, Sb, 5c, and Sd. A first removable medium for storing data in the form of a
fist optical
disk is inserted into one of the four optical disk drives Sa. After use, the
first optical disk
is removed and replaced with another optical disk. When the processor seeks
information
from the first optical disk, the user is prompted to reinsert it. The user
ejects one of the
optical disks in use and replaces it with the first optical disk. When the
same optical disk
drive Sa is used, the disk is easily recognisable. When a different optical
disk drive, for
example Sb, is used, the optical disk is accessible through a different
identifier.
A program in use on the processor seeking further data from the first optical
disk,
is thwarted because the first optical disk identifier is changed.
Alternatively, the first
optical disk is always reinserted into optical disk drive Sa and is therefore
always
recognisable. Unfortunately, this results in bottlenecks when two processes
each require
information from different optical disks within a same optical disk drive Sa.
It will be
evident to those of skill in the art that when the optical disk drive Sa forms
part of a file
server, the problem is compounded many fold.
Therefore, according to the invention a method is provided for storing data on
removable media such that they may be replaced in any of a number of removable
media
drives and yet remain accessible through a same identifier. The identifier is
recognisable
to the file system of the operating system of the computer system 1. That
said, as is
explained below, it is important that the identifier not be recognisable to
the system tools
of the operating system of the computer system 1.
With the advent of writable removable media, several problems have surfaced. A
common problem relates to file servers including banks of media. For example
when a
file server includes 50 optical media devices, a lot of files are immediately
accessible.
That said, some media are mounted but not inserted at any given time. Thus, a
directory
of those media requires the media be inserted within a device, be found, and
then that
directory data is loaded therefrom. File system utilities load this data for
users when
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executed and therefore require a lot of media swapping. A simple example will
help
outline the problem.
In this example, a system is in execution with 100 mounted removable storage
media and 30 physical removable storage media devices in the form of optical
disk
drives. A file system utility such as a file manager is loaded. The find file
function is used
to locate a specific file. The file manager is unaware of which disks are
physically
inserted and which are not so it tries to access the disks one at a time. The
result is that
the system requests the disks and disk swapping is performed. After much time
and much
disk swapping, the utility completes its task. Unfortunately, an individual
has wasted a lot
of time swapping disks. Alternatively, disk swapping is automated and, though
no person
has wasted time, the file system is slowed tremendously during the time the
find file
operation is performed.
Also, it is common to have a variety of archived files on the server at any
time.
Often, it is desired that the data is accessible to some people or programs
but not to
others. As noted above, this is difficult to achieve. According to the
invention, since the
system utilities do not recognise the removable media, the removable media are
not easily
located. By using obscure names, it can be readily achieved that a removable
medium is
very difficult to locate using trial and error and yet is fully accessible to
anyone who
knows exactly where to look. Advantageously, the method causes a storage
medium to be
difficult to find. That said, any program designed to access the medium has a
fixed
unchanging path for that medium and will therefore access the medium each time
correctly.
Referring to Fig. 3 a simplified flow diagram of a method according to the
invention is shown. A medium in the form of removable storage medium is
inserted
within a hardware device for accessing the medium. The medium is then mounted
in a
fashion such that it can be accessed by the file system for input/output
operations but
such that it cannot be accessed by the system utilities/tools.
Referring to Fig. 4 a simplified flow diagram of a method according to the
invention is shown. A medium in the form of removable storage medium is
inserted
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within a hardware device for accessing the medium. The medium is then mounted
by
creating a symbolic link to the medium using an identifier unique to the
medium. In this
fashion, the medium can be accessed by the file system for input/output
operations but it
cannot be accessed by the system utilities/tools.
Returning to the above example, when an individual accesses the system from a
remote site, they can employ system tools to locate files and to browse
storage media.
According to the invention, browsing of storage media is not possible absent
knowledge
in advance of the presence of the specific storage medium. This is not a fully
secure
solution, but tremendously enhances security for remote access to files. For
example, a
public directory on a non-removable drive such as drive C: is used. When data
from other
storage media is to be communicated, it is retrieved by a local process that
has a list of
mounted storage media. Thus, a remote user cannot browse the mounted storage
media
that are mounted according to the invention without first having a path
thereto. Such a
path may be very complicated and may include numerous characters. As such,
trial and
error is unlikely to work.
By allocating a unique and fixed identifier in the form of a drive name to
removable media, a file access path is no longer volatile. Hardware devices
and computer
systems are swappable as required without affecting the drive name. This is
highly
advantageous when shipping software products for use with data stored on a
removable
medium. The software accesses the removable medium by its identifier and, as
such, does
not need to search for the correct storage device. The software will function
equally well
across a communication medium, if designed to do so, since the storage medium
has a
known identifier. Even when the storage medium path is unknown or changes
frequently,
the software is stable.
This is also an advantage in operating systems where the number of usable
physical devices and/or media is restricted by the number of identifiers,
drive letters,
available. One such operating system is Windows NT~. Drive names as
implemented in
the preferred embodiment do not consume drive letters in such environments.
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A drive name according to the invention and for use with Windows NT~ consists
of a 64 character alpha-numeric including all special characters such as: $ %'
- - @ -' , .
I\ # & permitting the specification of an extremely large number of drive
names. For
example, drive name combinations using 26 alphabet characters, 10 digits and
14 special
characters would number 5064 or 5.421 x 10'°g.
Since drive names are hidden from operating system tools, the security of the
device and/or media is enhanced. Even though drive names are hidden, the
devices
referenced by those names are capable of being accessed with standard file
system
commands. This access is achieved using commands that allow a user to specify
the
actual path of the drive name. This is very different from mounting and
unmounting
devices. Each removable medium is mounted and remains mounted though the
graphical
user interface of Windows NT~ does not show the device as present.
Drive names are created by the creation of a symbolic link. A symbolic link
lets a
user create a filename or a directory name that, when used, is translated by
the operating
system into a different file or directory name. Referring to Fig. 2, a
simplified diagram of
a symbolic link is shown. An identifier that is stored on the physical
removable storage
medium is stored for the symbolic link. The identifier is preferably unique to
the
symbolic link and to the removable storage medium. The identifier is, for
example, in the
form of a name. The symbolic link contains other data for linking the name to
the
physical device where the named storage medium resides. This data is, for
example, in
the form of a physical path. The path is likely in the form of a hardware
address or an
address of a software device driver for the physical device or a combination
of the two.
Optionally, the symbolic link contains other information relating to the
status of storage
medium. Examples of further information include present/not present,
mounted/unmounted, read/read-write/write only, full, and so forth.
Referring to Fig. 5 a simplified flow diagram of a method according to the
invention is shown. A medium in the form of removable storage medium is
inserted
within a hardware device for accessing the medium. The medium is then mounted
and an
identifer is read therefrom. The identifier is preferably unique to the
storage medium. The
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symbolic links are then checked to see if one already exists for the
identifier of the
medium. When one exists, it is updated to reflect the physical drive in which
the medium
has most recently been inserted. Otherwise, a symbolic link to the medium is
created
using the identifier of the medium. In this fashion, the medium can be
accessed by the file
system for input/output operations but it cannot be accessed by the system
utilities/tools.
Current operating system implementations do not provide comparable
capabilities
for removable media devices. It is not obvious to create device names that are
inaccessible to an operating system. In fact, current operating system trends
and common
belief is that a more inclusive and knowledgeable operating system is required
to provide
ease of use, GUIs, improved performance, and better configurability. The
present
invention is in contrast to this current belief in the art. By implementing
the present
invention, it is believed that the ease of use and other benefits of modern
operating
systems are lost. This has found to not be the case.
Though the preferred embodiment relates to the use of removable storage media
1 S with Windows NT~ operating system, identifiers according to the invention
may be
associated with any type of media, such as read-only, write-once and
rewritable media
and identifiers are usable in most operating systems (OS).
In another alternative embodiment, the method is used with fixed storage media
and is used to hide them from view.
Numerous other embodiments of the invention may be envisaged without
departing from the spirit or scope of the invention.
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