GB2420640A

GB2420640A - Automatic monitoring and adjusting of the size of a partition of a logical unit

Info

Publication number: GB2420640A
Application number: GB0426115A
Authority: GB
Inventors: Preethi Rajeshwari; Srikanth Venkatsesshu
Original assignee: Hewlett Packard Development Co LP
Current assignee: Hewlett Packard Development Co LP
Priority date: 2004-11-29
Filing date: 2004-11-29
Publication date: 2006-05-31
Also published as: GB0426115D0

Abstract

The system includes a policy manager 11 which maintains a marker associated with a partition. The marker is used to determine when adjustment of the size of the partition is required, for example when a threshold amount of space has been used in the partition (step 17). A partition expansion module (39, Figure 2) then adjusts the size of the partition, IF there is insufficient space to expand the partition (step 20), the size of the logical unit may be expanded. Any volumes overlaying the partition may also be re-sized (step 36, Figure 2). The system may log activities in an event logger. The system operates automatically, without any manual intervention.

Description

1 2420640

AUTOMATIC ADJUSTMENT OF COMPUTER STORAGE RESOURCES

Field of Invention

This invention relates to storage resources used by a computer. In particular the invention relates to the adjustment of the storage space available to a host computer.

Background

Computer storage management involves the management of the storage resources available to a host computer. A host computer may be a desktop computer, a general purpose server, or a dedicated file server. The storage resources available to the host computer may take the form of direct attached storage (such as the internal hard disk of the computer), network attached storage (dedicated storage attached to the same network as the host computer), or a storage area network (a separate network which connects one or more computers with one or more storage resources). Independent of the type of host computer and storage resources, management of the storage resources is an essential task in the administration of the computer system.

The storage requirements of a host computer vary over the lifetime of the computer.

High capacity storage arrays are used to provide the physical storage space required. A storage array comprises an array of storage devices such as magnetic disks, optical disks or magnetic tapes. Management of storage arrays, particularly in a heterogeneous storage environment is a complex task. Virtualization is used to reduce the complexity of management of the storage devices.

Virtualisation involves the creation of virtual storage resources. The host computer accesses the virtual resource rather than the physical device. Physical storage devices such as the magnetic disks of a storage array underlie the virtual resources. There are a variety of methods of implementation of this type of virtualisation. In one implementation of virtualisation a fixed amount of space in the storage devices is dedicated to underlie a virtual storage resource.

A virtual storage resource is also known as a logical unit. When presented to the host computer, a virtual storage resource or logical unit appears to the operating system in the same way as an internal hard disk. Therefore, it can be partitioned and otherwise used by the operating system in the same way as an internal hard disk. A partition is a portion of the logical unit (or internal hard disk) which is defined by the operating system and assigned to a particular purpose. The partition can not be used for a purpose other than the purpose to which it is assigned.

As stated, physical storage devices underlie a virtual logical unit. Part or whole of one or more physical storage devices may underlie a single logical unit. Prior to use, the logical unit is partitioned, and the operation of the host computer results in utilization of the virtual storage space in a partition. At some point in the lifetime of the host computer, the remaining unused space in a partition will usually become insufficient and the partition will require expansion. Expansion of the partition can only occur if there is space in the logical unit, of which the partition forms a part, which has not been allocated to any partition. If there is no available space, the logical unit must be expanded before partition expansion can occur. The physical devices underlying the logical unit will often form part of a storage array (storage resource). A logical unit can only be expanded if there is sufficient available space in the storage resource underlying the logical unit. If there is insufficient space, additional storage devices (magnetic disks, optical disk, magnetic tape) must be added to the storage array.

Storage virtualization is advantageous in that additional physical storage capacity in the form of additional storage devices can be added to an existing storage array without disrupting the host computer. However, the additional storage capacity is not immediately available for use, since the host computer can only use space in the logical units. In order to make the additional capacity available, a logical unit must be expanded. Most storage arrays provide the capability to dynamically expand a logical unit when additional storage capacity is available in the storage array. However, a further step required before use can be made of the enlarged logical unit is the expansion of a partition of the logical unit which requires the additional space.

Conventionally, the ability to dynamically expand a logical unit does not translate into the ability to automatically expand a partition or any volume residing on a partition.

Therefore the entire process of space expansion, including logical unit expansion, partition expansion and volume expansion, is not easily automated.

Network Appliance Incorporated pioneered a network storage appliance known as a "filer". A filer has the ability to expand logical units when additional physical storage devices are available. However in order to make the additional space in the logical unit available to the operating system a special command must be issued. Therefore, the entire process of expansion of space is not automated. A further disadvantage of this solution is that a filer is a special purpose device which does not run applications or a general purpose operating system. Therefore, the method of expansion employed by a filer is specific to the operating system of the filer and cannot be adapted to other types of computer.

Sun Microsystems provide as part of the Solaris,7 Operating System a disk and storage management solution which enables the expansion of partitions and volume by means of a command interface. This is not an automated space expansion system. The solution is not able to expand the size of a logical unit, but instead, this expansion is performed by other utilities. Furthermore, this solution is only able to operate as part of the Solaris operating system.

The EMC Clariion,torage Solution provides a method of expanding the space (logical unit, partition, volume) available to a host computer running a Windows operating system. As with the other prior art solutions mentioned, this solution enables additional physical storage devices to be added to a storage array without disrupting the host computer. However the expansion of a logical unit, partition and volume in the EMC Clariion solution is achieved through a series of manual operations performed by a system administrator. The method of space expansion is not automated.

As can be seen from the description of the above prior art, there is not disclosed a generic method of space expansion which can be used on any host computer independent of the operating system running on that computer.

A further disadvantage of the prior art solutions is that in order for a partition to be expanded before it runs out of space a system administrator must continuously monitor the free space in the partition to determine when partition expansion should be initiated.

This is a time consuming task for the system administrator. None of the prior art solutions provide a means whereby partition expansion can be performed on an as neededlrequired' basis.

Yet another disadvantage of the known prior art is that it does not disclose an ability to automatically expand a logical unit, when the logical unit is based on a storage array which is not integrated with the expansion system. In conventional solutions, when the system administrator identifies that there is a need to expand a logical unit, they must identify the vendor of the storage array on which the logical unit is based and initiate expansion via means specific to that storage array. The prior art does not disclose a system wherein it is possible for there to be uniform treatment of physical storage arrays independent of the vendor of the array.

It is an object of the invention to provide a system and method for the timely automatic adjustment of logical unit size, partition size and volume size, which overcomes or at least mitigates some of the abovementioned limitations of known space expansion systems and methods.

It is a further object of the invention to provide a system and method capable of interoperability with any operating system and with the physical storage resources of any identified third party storage vendor.

Summary of Invention

In a first aspect of the invention there is provided a computer implemented method for automatically monitoring the size of a partition including the steps of associating a marker with the partition; determining when adjustment of the size of the partition is required having regard to the marker; and generating a notification when adjustment of the size of a partition is required.

In a preferred embodiment the marker indicates a threshold amount of space less than the total amount of space in the partition and the threshold may be a percentage of the space in the partition. The threshold may be set to a default value or be configured by a system administrator.

It is preferred that the determination of when adjustment of the size of the partition is required includes consideration of the amount of space in the partition which has been used, and the marker.

A preferred embodiment also includes automatic adjustment of the size of a partition wherein the partition is adjusted by a defined amount which may be a default value dependent on the size of the partition or configurable by a system administrator.

Preferably after adjustment of the partition the marker is recalculated.

It is also preferred that where the partition resides on a logical unit the method includes the step of determining whether there is sufficient space available in the logical unit to accommodate adjustment to the partition. This determination preferably includes consideration of the amount of space in the logical unit which is not allocated to any partition and the amount by which the size of the partition is to be adjusted. If it is determined that there is insufficient space available in the logical unit, the size of the logical unit is adjusted. Adjustment of the size of the logical unit preferably includes the steps of identifying a storage device underlying the logical unit; invoking functions provided by a vendor of the storage device; and adjusting the size of the logical unit.

In a preferred embodiment the logical unit is adjusted by a defined amount which may be configurable by a system administrator.

Preferably, the method of the invention also includes the step of determining whether a volume resides on the partition, and if so, adjusting the size of the volume.

Furthermore, the invention preferably includes the step of generating a notification at the completion of the steps of the method.

In a second aspect the invention provides for a system for automatically adjusting the size of a partition of a logical unit including a policy manager computer module adapted to maintain a marker associated with the partition; a monitoring computer module adapted to determine when adjustment of the size of the partition is required having regard to the marker; and a partition expansion computer module adapted to adjust the size of the partition when the monitoring module determines that expansion is required.

Preferably the marker indicates a threshold amount of space less than the total amount of space in the partition.

In a preferred embodiment the policy manager computer module is also adapted to maintain a parameter determining the amount by which the logical unit may be adjusted and is also adapted to maintain a parameter determining the amount by which the partition may be adjusted.

It is preferred that the monitoring computer module is implemented as a computer daemon. Preferably the determination performed by the monitoring computer module has regard to the amount of space in the partition which has been used and the marker.

In a further preferred embodiment the invention includes an application computer module adapted to determine whether there is sufficient space available in the logical unit to accommodate adjustment of the partition. When it is determined that adjustment of the size of the partition is required the monitoring computer module is also adapted to alert the application computer module. Preferably the determination performed by the application computer module has regard to the amount of space in the logical unit which is not allocated to any partition and the amount by which the size of the partition is to be adjusted.

It is also preferred that the system further includes an expansion manager computer module adapted to determine whether a volume resides on the partition and a generic interface computer module adapted to initiate expansion of the logical unit. Preferably the generic interface computer module identifies a vendor of a storage resource underlying the logical unit and is adapted to invoke functions provided by a vendor of a storage resource. Furthermore the generic interface computer module preferably adjusts the size of the logical unit and communicates to the expansion manager computer module the amount by which the logical unit has been adjusted.

In a preferred embodiment if the application computer module determines that there is sufficient space available in the logical unit to adjust the partition, the application computer module invokes the expansion manager computer module, however, if the application computer module determines that there is not sufficient space available in the logical unit to adjust the partition, the application computer module invokes the generic interface computer module and communicates to the generic interface computer module the amount by which the logical unit is to be adjusted.

The invention furthermore preferably includes a volume expansion computer module adapted to adjust the size of the volume if a volume which resides on the partition. It is preferred that the partition expansion computer module is adapted to adjust the partition with reference to the parameter maintained by the policy manager computer module.

Preferably, the invention also includes an event logger computer module adapted to log activities of the other modules of the system including identification number of a partition, the amount by which a logical unit is adjusted and the amount by which a disk partition is adjusted. A further preferred inclusion is a user interface computer module adapted to enable a user of the system to configure a parameter and further adapted to enable a user of the system to view the information logged by the event logger module.

In another aspect of the invention there is provided an apparatus for automatically adjusting the size of a partition of a logical unit including a storage device; computer memory for maintaining a marker associated with the partition and a computer processor adapted for determining when adjustment of the size of the partition is required having regard to the marker; determining whether there is sufficient space available in the logical unit to accommodate adjustment to the partition; if there is not sufficient space available in the logical unit, adjusting the size of the logical unit; adjusting the size of the partition; determining whether a volume resides on the partition; and if a volume resides on the partition, adjusting the size of the volume. In a preferred embodiment the storage device is a disk array.

In yet another aspect the invention provides for a computer program which when executed performs the method as of the invention. Preferably the computer program is platform independent.

In yet a further embodiment, the invention provides for a storage system adapted to operate in accordance with the invention as hereinbefore defined.

Brief Description of Drawings

The invention will now be described by way example only, with reference to the accompanying drawings in which: Figures 1 and 2: Show a flow diagram of the method of one embodiment of the invention showing an automatic size management system and the computer module responsible for the main steps of the method; Figure 3: Shows the relationship between the automatic size management system and storage resources according to an embodiment of the invention; Figures 4 to 6: Show a series of example storage array, logical unit, partition and volume arrangements at various states of the operation of the system according to an embodiment of the invention; and Figure 7 Shows the apparatus of one embodiment of the automatic size management system.

Detailed Description of the Invention

The physical storage resources used by a computer may include a variety of resources including an internal magnetic disk or external resources including magnetic disks, optical disks, magnetic tapes, an array of these devices or a combination of any of these.

A physical storage resource is a collection of one or more physical storage devices. A logical unit is a virtual storage resource of a fixed size which overlies a physical storage resource such as a magnetic disk array. The physical resource is not "visible" to the host computer, and the logical unit is "viewed" by the host computer as a physical resource. This virtualisation simplifies management of the physical devices which make up the storage resource.

The operating system can partition a logical unit and allocate each partition to a specific use. Each partition is of a fixed size and the total size of all partitions on a logical unit cannot exceed the size of the logical unit. As the storage space in each partition becomes occupied through normal operation of the computer the amount of free space in a partition diminishes until eventually the partition runs out of free space. This is highly undesirable as it interferes with computer processes which use the partition. It is preferred that a partition is expanded before this situation occurs. In order to expand a partition there must be space available in the logical unit, which is currently unallocated to any partition. If there is no such space, the logical unit must be expanded. The expansion of the logical unit involves the allocation of further physical storage device space for use by the logical unit. This allocation of further space depends on the availability of such space in the physical storage resource.

A volume is a virtual entity which overlies a partition. A partition may or may not have an overlying volume. Where a partition does have an overlaying volume, the size of the volume corresponds to the full size of the partition. A single volume may overlie more than one partition. A volume is managed by a file system. The file system is thereby able to store and retrieve files from any partition underlying the volume being managed.

A partition which does not have an overlying volume is a raw partition.

The automatic size management system performs the adjustment of the size of logical unit and partition space. It also performs the adjustment of the size of any volume which may overlie on an expanded partition.

Figure 1 shows a flow diagram of a method according to one embodiment of the automatic size management system and a computer module responsible for the main steps of the method. An initial step in the method is the configuration of the policy manager module 11. Parameters which can be configured include the incremental expansion value for each partition (step 12) and the incremental expansion value for each logical unit (step 13). These parameters may indicate an expansion value determined by a proportion of the existing size of the logical unit or partition, for example 50 percent of the existing size.

Preferably the parameter indicating the expansion value for a logical unit (step 13) indicates that the logical unit is to be expanded by thc amount required to satisfy the expansion of a partition. The parameter indicating the expansion value for a partition (step 12) preferably indicates that the partition is to be expanded to occupy all currently unallocated space in the logical unit. The implementation of the policy manager module 11 may set these parameters to default values. The parameters may also be configurable by a system administrator. A graphical user interface is provided to enable the system administrator to configure the parameters. In one embodiment, the policy manager module 11 may be implemented to give a system administrator the option of configuring the parameters at any time before or after default values are set.

The policy manager module 11 also maintains a parameter indicating the threshold at which a marker associated with each partition is to be set (step 14). This parameter may be set to a proportion of the size of the partition, for example 80 percent. The value of this parameter may also be set to a default and may be configurable by a system administer.

The monitoring module 15 performs the task of monitoring the amount of storage space used in each partition (step 16). The monitoring module may be implemented as a computer daemon. The module interacts with the policy manager module 11 to determine whether the amount of storage space used (step 16) has reached the threshold amount of storage space indicated by the marker associated with that partition (step 17).

When use of a partition reaches the threshold indicated by the marker, the monitoring module alerts the application module (step 18).

Upon receiving an alert from the monitoring module 15, the application module 19 determines (step 20) whether there is sufficient unallocated space in the logical unit to accommodate the expansion of the partition. The amount by which the partition is to be expanded is determined by the parameter maintained by the policy manager module 11.

If it is found that there is sufficient space in the logical unit, the application module 19 invokes (step 21) the expansion manager module 35. If it is found that there is insufficient space the application module 19 invokes (step 22) the generic interface module 31.

The generic interface module provides an interface between the automatic size management system and the physical storage resources. Figure 3 shows the relationship between the automatic size management system and the physical storage resources. The automatic size management system 52 is shown to be operating on a host computer 51.

The generic interface module 55 is related to the other modules in the system 53 through the application module 54. The physical storage resources are magnetic storage disk arrays 59, 60 shown external to the host computer 51. It is the role of the generic interface module 55 to adjust the size of a logical unit. This requires communication with the storage resources 59, 60, through the vendor functions 56, 57, to determine whether there is sufficient physical storage space to support the expansion of the virtual storage space in the logical unit.

Conventionally, the means of communication with the storage devices varies with each storage vendor. Therefore, either an expansion system is limited to interoperating with the storage resources provided by only a single vendor, or manual intervention by a system administrator is required. The embodiment of the invention described herein is interoperable with the storage resources of any vendor who has registered with the system. Registration involves provision of a library of functions which can be invoked by the generic interface module. The functions provide an interface through which the generic interface module can request further physical storage resources to be allocated to a logical unit. The library functions provided by the vendor of the storage resources may, for example, be implemented as a Dynamic Link Library, or as a Shared Library, depending on the platform on which the invention is operating. The requirement for registration ensures that all storage vendors provide an interface through which the underlying physical storage resources can be manipulated. It also allows storage vendors to easily make their storage resources interoperable with the system.

When invoked by the application module 54 the generic interface module 55 must identify the vendor of the storage resource underlying the logical unit which requires expansion and determine whether the vendor has registered with the system 52 (figure 2, step 32). Referring to figure 3, there may be more than one storage resource 59, 60 accessible by the host computer. However, a single logical unit may be based on only one storage resource. The generic interface module invokes the appropriate functions 56, 57 provided by the registered vendor (figure 2, step 33). These functions may include a function to determine whether the storage resource allows the logical unit to be expanded, whether there is further space available in the storage array which can be allocated to the logical unit; a function to allocate the required amount of space to the logical unit; and any other functions necessary to perform supplementary tasks such as communicating to the generic interface module 55 the amount of space by which the logical unit may be expanded.

Referring once again to figure 2, once the generic interface module 31 has confirmed that the logical unit may be expanded, the expansion of the logical unit is performed and this is communicated to the expansion manager module (step 34), along with the actual size by which the logical unit has been expanded. The generic interface module 31 then invokes (step 34) the expansion manager module 35.

The expansion manager module 35 determines whether there is a volume overlying the partition (step 36). If there is such a volume, the partition expansion module 39 is invoked (step 37) and the volume expansion module 43 is also invoked (step 44).

Otherwise, only the partition expansion module 39 is invoked (step 38).

The partition expansion module 39 handles the expansion of the partition on the logical unit. The partition is expanded (steps 40 and 41) by the amount determined by the policy manager module 11. If the volume expansion module 43 is also invoked (step 44) this module expands the volume (step 45) overlying the recently expanded partition (step 40). The volume is expanded to occupy the full size of the partition.

In a preferred embodiment an event logger module generates and logs informational messages and notifications when a partition is expanded. The event logger records such information as the logical unit of which the partition to be expanded forms a part, the amount of expansion of the logical unit (if required), the amount of expansion of the partition, the vendor of the storage device underlying the logical unit, notification that expansion has occurred, and the time of the expansion.

Also in a preferred embodiment a graphical user interface module provides an interface for a system administrator or management application to perform such tasks as the configuration of parameters and to access information recorded by the event logger module.

In a further embodiment of the invention, the modules described are not distinct and one computer module may perform the tasks described above as being performed by more than one module.

While the present embodiment of the invention has been described with respect to the expansion of a logical unit, partition and volume, it is intended that reduction of the size of a logical unit, partition and volume is also possible according to the principles described.

The operation of the method will now be described by example with reference to figures 4to6.

Storage array 81 provided by a storage vendor consists of five disk drives 82, 83, 84, 85, 86 where each disk has a capacity of five gigabytes. A logical unit 87 is created with a total size of fifleen gigabytes. The storage array determines which disk drives will underlie the logical unit. In this example, it is assumed that disk drives 82, 85 and 86 underlie the logical unit 87. The logical unit 87 is available to the operating system of a host computer.

The logical unit 87 is divided into a first partition 88 and a secondpartition 89. The partitions are of size five gigabytes and seven gigabytes respectively. Three gigabytes remain unallocated 90. The first partition 88 is a raw partition. The second partition 89 has an overlaying volume 91 managed by a file system.

A marker 92, 93 is associated with each partition 88, 89. By default this marker indicates a threshold of eighty percent of the total space in the associated disk partition 88, 89. Therefore, markers 92 and 93 indicate thresholds of 4 gigabytes arid 5.6 gigabytes respectively.

During the course of operation of the host computer, space in partition 89 is used. If it is assumed that 5.6 gigabytes of space in partition 89 has been used, use of this partition has reached the threshold indicated by the marker 93. The automatic size management system recognizes the need for expansion of partition 89.

In this example, the amount by which partition 89 is to be expanded has been set to fifty percent of the current size of the partition, thus, 3.5 gigabytes. The amount of unallocated space 90 in the logical unit 87 is 3 gigabytes, which is insufficient to accommodate the 3.5 gigabytes required. Therefore, logical unit expansion must occur before the partition 89 can be expanded. If the amount by which partition 89 was to be expanded was 1 gigabyte, logical unit expansion would not have been necessary.

The amount by which the logical unit is to be expanded is set to 40 percent of the current size of the logical unit, thus 6 gigabytes. The vendor of the storage array 81 is identified. The size requirement of 6 gigabytes is communicated to the library function.

The storage array performs the task of allocating a further 6 gigabytes of disk space to the logical unit.

Referring to figure 5, it will be assumed that the whole of disk 103 and 1 gigabyte of disk 104 have been allocated to the logical unit by the storage array. After logical unit expansion, the total size of the logical unit is 21 gigabytes. Before partition expansion has occurred the logical unit 107 will comprise first 108 and second 109 partitions, of sizes 5 gigabytes and 7 gigabytes respectively and unallocated space 110 of 9 gigabytes.

Following logical unit expansion there is sufficient unallocated space 110 in the logical unit to accommodate the further 3.5 gigabytes required by partition 109. Partition 109 is expanded to include an additional 3.5 gigabytes.

Referring to figure 6, following partition expansion, the logical unit 127 will comprise first 128 and second 129 partitions of sizes 5 gigabytes and 10.5 gigabytes respectively and unallocated space 130 of 5. 5 gigabytes. The size of the first partition 128 remains unchanged as use of this partition has not yet reached the threshold indicated by the marker 132. Partition 129 is now 10.5 gigabytes, expanded by 3.5 gigabytes from its original size of 7 gigabytes.

Following partition expansion, the system determines whether there is a volume overlaying the recently expanded partition 129. In this example it can be seen that there is such a volume 131. The volume 131 is expanded to occupy the full size of the expanded partition.

In a further step following partition expansion, the threshold indicated by the marker iS 133 associated with the expanded partition 129 must be recalculated. As the marker in this example indicates a threshold of eighty percent of the total space in the associated partition, the marker 133 is recalculated to indicate a threshold of 8.4 gigabytes.

The method of the invention may be implemented as a computer program. In a preferred embodiment, such a computer program does not contain any platform specific features, but is implemented in generic language so that it is platform independent.

Figure 7 shows the apparatus of an exemplary embodiment of the invention. A computer processor 140 is adapted to interact with computer memory 141 which may store parameters maintained by the automatic size management system. The computer processor 140 also interacts with a storage device 142 as described above.

Thus there is provided a method, system and apparatus for the automatic adjustment of the size of a partition of a logical unit where the expansion of the partition may also require expansion of a logical unit of which the partition forms a part and the expansion of a volume overlaying the partition. This is advantageous in that the entire sequence of space expansion is automated, thereby eliminating the need for intervention by a system administrator. The automation of space expansion also ensures more timely expansion, thereby minimising the risk that a partition will run out of available space. This is also advantageous in that it can operate on a host computer irrespective of the operating system used on the computer, thus providing a generic solution to automatic space expansion. Further advantages are provided in that the method is interoperable with storage devices provided by any storage vendor. This further adds to the generality of the solution.

While the present invention has been illustrated by the description of the embodiments thereof and while the embodiments have been described in detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus and method, and illustrative examples shown and described. Accordingly, departures may be made from such details without departure from the spirit or scope of the Applicant's general inventive concept.

Claims

What we claim is 1. A computer implemented method for automatically

monitoring the size of a partition including the steps of: a. associating a marker with the partition; b. determining when adjustment of the size of the partition is required having regard to the marker; and c. generating a notification when adjustment of the size of a partition is required.
2. A method as claimed in claim 1 wherein the marker indicates a threshold amount of space less than the total amount of space in the partition.
3. A method as claimed in claim 2 wherein the threshold is a percentage of the total amount of space in the partition.
4. A method as claimed in claim 2 or 3 wherein the threshold is set to a default value.
5. A method as claimed in claim 2 or 3 wherein the threshold is configurable by a system administrator.
6. A method as claimed in any preceding claim wherein step (b) includes consideration of the amount of space in the partition which has been used, and the marker.
7. A computer implemented method for automatically monitoring and adjusting the size of a partition including automatically monitoring the size of a partition as claimed in any one of claims 1 to 6 and adjusting the size of the partition.
8. A method as claimed in claim 7 wherein the partition is adjusted by a defined amount.
9. A method as claimed in claim 8 wherein the defined amount is a default value dependent on the size of the partition.
10. A method as claimed in claim 8 wherein the defined amount is configurable by a system administrator.
11. A method as claimed in any one of claims 7 to 10 wherein after adjustment of the partition the marker is recalculated.
12. A method as claimed in any one of claims 7 to 11 wherein the partition resides on a logical unit and the method includes the step of determining whether there is sufficient space available in the logical unit to accommodate adjustment to the partition.
13. A method as claimed in claim 12 wherein the determination includes consideration of the amount of space in the logical unit which is not allocated to any partition and the amount by which the size of the partition is to be adjusted.
14. A method as claimed in claim 12 or 13 wherein if there is not sufficient space available in the logical unit, the size of the logical unit is adjusted.
15. A method as claimed in claim 14 including the steps of: a. identifying a storage device underlying the logical unit; b. invoking functions provided by a vendor of the storage device; and c. adjusting the size of the logical unit.
16. A method as claimed in claim 14 or 15 wherein the logical unit is adjusted by a defined amount.
17. A method as claimed in claim 16 wherein the defined amount is configurable by a system administrator.
18. A method as claimed in any of claims 7 to 17 including the step of determining whether a volume resides on the partition.
19. A method as claimed in claim 18 including the step of adjusting the size of the volume if a volume resides on the partition.
20. A method as claimed in any preceding claim including the step of generating a notification at the completion of the steps of the method.
21. A system for automatically adjusting the size of a partition of a logical unit including: a. a policy manager computer module adapted to maintain a marker associated with the partition; b. a monitoring computer module adapted to determine when adjustment of the size of the partition is required having regard to the marker; c. a partition expansion computer module adapted to adjust the size of the partition when the monitoring module determines that expansion is required.
22. A system as claimed in claim 21 wherein the marker indicates a threshold amount of space less than the total amount of space in the partition;
23. A system as claimed in claim 21 or 22 wherein the policy manager computer module is also adapted to maintain a parameter determining the amount by which the logical unit may be adjusted.
24. A system as claimed in any of claims 21 to 23 wherein the policy manager computer module is also adapted to maintain a parameter determining the amount by which the partition may be adjusted
25. A system as claimed in any of claims 21 to 24 wherein the monitoring computer module is implemented as a computer daemon.
26. A system as claimed in any of claims 21 to 25 wherein the determination performed by the monitoring computer module has regard to the amount of space in the partition which has been used and the marker.
27. A system as claimed in any preceding claim further including an application computer module adapted to determine whether there is sufficient space available in the logical unit to accommodate adjustment of the partition.
28. A system as claimed in claim 27 wherein the monitoring computer module is also adapted to alert the application computer module when it is determined that adjustment of the size of the partition is required.
29. A system as claimed in claim 27 or 28 wherein the determination performed by the application computer module has regard to the amount of space in the logical unit which is not allocated to any partition and the amount by which the size of the partition is to be adjusted.
30. A system as claimed in any of claims 27 to 29 further including an expansion manager computer module adapted to determine whether a volume resides on the partition.
31. A system as claimed in any of claims 27 to 30 further including a generic interface computer module adapted to initiate expansion of the logical unit
32. A system as claimed in any of claims 31 wherein the generic interface computer module identifies a vendor of a storage resource underlying the logical unit.
33. A system as claimed in claim 31 or 32 wherein the generic interface computer module is adapted to invoke functions provided by a vendor of a storage resource.
34. A system as claimed in any of claims 31 to 33 wherein the generic interface computer module adjusts the size of the logical unit and communicates to the expansion manager computer module the amount by which the logical unit has been adjusted.
35. A system as claimed in any of claims 30 to 34 wherein if the application computer module determines that there is sufficient space available in the logical unit to adjust the partition, the application computer module invokes the expansion manager computer module.
36. A system as claimed in any of claims 31 to 35 wherein if the application computer module determines that there is not sufficient space available in the logical unit to adjust the partition, the application computer module invokes the generic interface computer module and communicates to the generic interface computer module the amount by which the logical unit is to be adjusted.
37. A system as claimed in any preceding claim further including a volume expansion computer module adapted to adjust the size of the volume if a volume which resides on the partition.
38. A system as claimed in any of claims 21 to 37 wherein the partition expansion computer module is adapted to adjust the partition with reference to the parameter maintained by the policy manager computer module.
39. A system as claimed in any of claims 21 to 38 including an event logger computer module adapted to log activities of the other modules of the system.
40. A system as claimed in claim 39 wherein the event logger computer module records identification number of the partition.
41. A system as claimed in any of claims 39 to 40 wherein the event logger computer module records the amount by which the logical unit is adjusted.
42. A system as claimed in any of claims 39 to 41 wherein the event logger computer module records the amount by which the disk partition is adjusted.
43. A system as claimed in any of claims 21 to 42 including a user interface computer module adapted to enable a user of the system to configure a parameter.
44. A system as claimed in any of claims 21 to 43 including a user interface compute module adapted to enable a user of the system to view the information logged by the event logger module.
45. An apparatus for automatically adjusting the size of a partition of a logical unit including: a. a storage device; b. computer memory for maintaining a marker associated with the partition.

c. a computer processor adapted for determining when adjustment of the size of the partition is required having regard to the marker; determining whether there is sufficient space available in the logical unit to accommodate adjustment to the partition; if there is not sufficient space available in the logical unit, adjusting the size of the logical unit; adjusting the size of the partition; determining whether a volume resides on the partition; and if a volume resides on the partition, adjusting the size of the volume.
46. An apparatus as claimed in claim 45 wherein the storage device is a disk array.
47. A computer program which when executed performs the method as claimed in any one of claims 1 to 20.
48. A computer program as claimed in claim 47 wherein the computer program is platform independent.