Abstract: A storage unit includes one or more storage devices. In one embodiment, it is determined whether a temperature associated with the storage unit is below a minimum threshold. In another embodiment, it is determined whether a predicted heat load of the storage unit is below a minimum threshold. A predicted heat load for the storage unit is increased by initiating a data operation in the storage devices in response to determining that the temperature, or the predicted heat load, is below the minimum threshold.

Abstract: A file system and method of file access are disclosed. In a particular embodiment, a method is performed at a host device coupled to a non-volatile memory, where the host device includes a memory having a first file data structure. A first directory entry in a file directory of a file system is located where the first directory entry corresponds to a first file stored in the non-volatile memory. First data associated with the first directory entry, including first location data indicating a location of the first file in the non-volatile memory, is retrieved and stored in the first file data structure. A request to open the first file is received. In response, the first location data of the first file is retrieved from the first file data structure and data of the first file from the non-volatile memory is read. First metadata associated with the first file is extracted from the data read from the non-volatile memory.

Abstract: Systems, computer readable media, and methods are provided. An example method can include classifying a plurality of storage mapping systems as a plurality of storage tiers in a datacenter, assigning a chargeback level to each of the plurality of storage tiers, analyzing a plurality of storage volumes of a plurality of servers in the datacenter to obtain characteristics of each of the plurality of storage volumes where the characteristics include one of the plurality of storage mapping systems, assigning the chargeback level to each of the plurality of storage volumes based on the storage mapping system for each of the plurality of storage volumes, and determining a storage recommendation for a number of configuration item (CIs) based on a criticality of the number of CIs where the criticality corresponds to at least one of the chargeback levels assigned to each of the plurality of storage tiers.

Abstract: A virtual memory management unit can implement various techniques for managing paging space. The virtual memory management unit can monitor a number of unallocated large sized pages and can determine when the number of unallocated large sized pages drops below a page threshold. Unallocated contiguous smaller-sized pages can be aggregated to obtain unallocated larger-sized pages, which can then be allocated to processes as required to improve efficiency of disk I/O operations. Allocated smaller-sized pages can also be reorganized to obtain the unallocated contiguous smaller-sized pages that can then be aggregated to yield the larger-sized pages. Furthermore, content can also be compressed before being written to the paging space to reduce the number of pages that are to be allocated to processes. This can enable efficient management of the paging space without terminating processes.

Abstract: A cell broadband engine processor includes memory, a power processing element (PPE) coupled with the memory, and a plurality of synergistic processing elements. The PPE creates a SPE as a computing SPE for an application. The PPE determines idles ones of the plurality of SPEs, and creates a managing SPE from one of the idle SPEs. Each of the plurality of SPEs is associated with a local storage. The managing SPE informs the computing SPE of a starting effective address of the local storage of the managing SPE and an effective address for a command queue. The managing SPE manages movement of data associated with computing of the computing SPE based on one or more commands associated with the application. A computing SPE sends the one or more commands to the managing SPE for insertion into the command queue.

Abstract: Provided are a computer program product, system, and method for granting and revoking supplemental memory allocation requests. Supplemental memory allocations of memory resources are granted to applications following initial memory allocations of the memory resources to the applications. In response to determining that available memory resources have fallen below an availability threshold, determining a weighting factor for each supplemental memory allocation based on at least one of an amount of the memory resources allocated to the supplemental memory allocation and a measured duration during which the memory resources have been allocated. At least one of the supplemental memory allocations is selected to revoke based on the determined weighting factors of the supplemental memory allocations.

Abstract: According to one embodiment, a system includes logic adapted to: receive a request to open an existing data set indicating a write operation, receive new data to write to the existing data set, determine that the existing data set is stored on a lower tier of a tiered data storage system, determine that the existing data set is capable of being updated by appending the new data to an end of the existing data set, create a temporary data set on a higher tier of the tiered data storage system comprising the new data, associate the temporary data set on the higher tier of the tiered data storage system with the existing data set on the lower tier of the tiered data storage system, and create a write indicator associated with the new data set indicating that the new data set belongs at the end of the existing data set.

Abstract: Provided is a memory switching control apparatus using an open serial interfacing scheme capable of enhancing flexibility, reliability, availability, performance in a data communication processes between a memory and a processing unit and an operating method thereof. The memory switching control apparatus includes: one or more processor interfacing units which perform interfacing with one or more processing units; one or more memory interfacing units which have open-serial-interfacing-scheme memory interfacing ports to interface with data storage devices connected to the memory interfacing ports in a serial interfacing scheme; and a plurality of arbitrating units which are provided corresponding to the memory interfacing units to independently arbitrate usage rights of the processor interfacing units to the memory interfacing units.

Abstract: Various systems and methods are described for configuring a logical data storage container. In one embodiment, an instruction to perform an operation to modify an attribute of the logical data storage container that is an abstraction of a plurality of pertinent storage containers is received. A translated instruction to perform a sub-operation associated with the operation is transmitted to each of a number of the plurality of pertinent storage containers. A level of success of the performing of the operation on the logical data storage container is detected based on a comparison of a threshold value to a level of success of the performing of the sub-operation on each of the number of the plurality of pertinent storage containers. A report of the detected level of success is communicated.

Abstract: There is provided an information processing apparatus including a primary storage apparatus configured by combining a plurality of memories each having a different upper limit of a number of possible rewrites, and an allocation management section configured to allocate a storage area of data to be stored in the primary storage apparatus to one of the plurality of memories based on a rewrite frequency of the data.

Abstract: A memory management apparatus includes a first controller adapted to receive an input data sequence including one or more data frames and operative: to separate each of the data frames into a payload data portion and a header portion; to store the payload data portion in at least one available memory location in a physical storage space; and to store in a logical storage space the header portion along with at least one associated index indicating where in the physical storage space the corresponding payload data portion resides. The apparatus further includes a second controller operative, as a function of a data read request, to access the physical storage space using the header portion and associated index from the logical storage space to retrieve the corresponding payload data portion and to combine the header portion with the payload data portion to generate a response to the data read request.

Abstract: Various technologies and techniques are disclosed for providing type stability techniques to enhance contention management. A reference counting mechanism is provided that enables transactions to safely examine states of other transactions. Contention management is facilitated using the reference counting mechanism. When a conflict is detected between two transactions, owning transaction information is obtained. A reference count of the owning transaction is incremented. The system ensures that the correct transaction was incremented. If the owning transaction is still a conflicting transaction, then a contention management decision is made to determine proper resolution. When the decision is made, the reference count on the owning transaction is decremented by the conflicting transaction. When each transaction completes, the reference counts it holds to itself is decremented. Data structures cannot be deallocated until their reference count is zero.

Abstract: Various embodiments for performing truncate operations in nonvolatile memory are described. In one embodiment, an apparatus may include a nonvolatile memory to perform one or more truncate operations on a data file written to the nonvolatile memory and a volatile memory to track a truncate operation performed in the nonvolatile memory. Other embodiments are described and claimed.

Abstract: A storage system includes at least one storage device on which are provided data storage volumes and an extended storage volume. The data storage volumes include a first data storage volume that is implemented with a data protection mechanism, and a second data storage volume that is implemented without the data protection mechanism. Also, an extended storage volume is provided that is initially un-allocated to any of the data storage volumes. A controller dynamically allocates at least one portion of the extended storage volume to the particular data storage volume to dynamically expand storage capacity of the particular data storage volume.

Abstract: A method and system for estimating space in a compressed volume to enable a storage server to respond to write requests before actually compressing and/or allocating data on disk. In some embodiments, in response to receiving a request to store data, the storage server estimates the amount of storage space required to store the data on disk. The storage server compares the estimated amount with the amount of available disk space. When the amount of available disk space is less than the estimated space, the storage server sends a response indicating that the request failed. Otherwise, when the amount of available disk space is greater than or equal to the estimate space, the storage server sends a response indicating that the request succeeded. The response is sent before the storage server allocates any disk space in connection with the request.

Abstract: A controller in a storage system receives a capacity change command specifying a device, and changes, to a volume capacity value indicating a storage capacity following the capacity change command, a volume capacity value of a virtual volume associated with the device specified in management information, which includes the volume capacity value indicating a storage capacity of the virtual volume. As such, without increasing or decreasing the number of logical volumes associated with a device provided by a host device, the device can be changed in storage capacity.

Abstract: Embodiments of the invention provide methods and apparatus for controlling data volume creation at the storage system. In one embodiment, a storage system comprises a processor; a memory; and a plurality of chunks that are to be allocated to data volumes, each chunk having one or more data blocks. The plurality of chunks include zero or more used chunks which are allocated to one or more data volumes, and zero or more remaining chunks which are not used chunks. A new data volume creation operation to create a new data volume is prohibited or warned against before the new data volume is created, in accordance with a total number of the remaining chunks in the storage system. The remaining chunks may further include reserved chunks which are reserved for use in one or more data volumes but have not been allocated.

Abstract: Resources of an address space are managed in dynamically sized ranges, extents, sets, and/or blocks. The address space may be divided into regions, each corresponding to a different, respective allocation granularity. Allocating a block within a first region of the address space may comprise allocating a particular number of logical addresses (e.g., a particular range, set, and/or block of addresses), and allocating a block within a different region may comprise allocating a different number of logical addresses. The regions may be configured to reduce the metadata overhead needed to identify free address blocks (and/or maintain address block allocations), while facilitating efficient use of the address space for differently sized data structures.

Abstract: Provided are a computer program product, system and method for managing Input/Output (I/O) requests to a storage device. In response to a write request, a determination is made as to whether preserve mode is enabled. A first entry is located in a volume control table for the logical address to write indicating a version number of the data and a first physical location in the storage device. The write data is written to a second physical location in the storage device. If the preserve mode is enabled, a second entry is added to the volume control table for the logical address, the volume control table is updated to have the first or second entry for the logical address point to the second physical location and indicate a current version, and the first or second entry not indicating the current version indicates the first physical location and a previous version.

Abstract: An improved approach is described for analyzing and estimating products having arrays of uncommitted logic, and matching these products to electronic designs. The approach can be applied to any type of product that include arrays of uncommitted logic, such as gate arrays and field programmable gate arrays. An approach is described for performing memory mapping in the context of selecting an electronic product having an array of uncommitted logic.

Abstract: Certain embodiments described herein include a memory system which can communicate with a host system such as a disk controller of a computer system. The memory system can include volatile and non-volatile memory and a controller which are configured such that the controller backs up the volatile memory using the non-volatile memory in the event of a trigger condition. In order to power the system in the event of a power failure or reduction, the memory system can include a secondary power source which is not a battery and may include, for example, a capacitor or capacitor array. The memory system can be configured such that the operation of the volatile memory is not adversely affected by the non-volatile memory or the controller when the volatile memory is interacting with the host system.

Abstract: Garbage collection processes are automatically tuned on a system comprising a plurality of virtual machines running on a physical processing device with multiple physical processors. Tuning is implemented for each garbage collection process, by updating a load variable to reflect that a new garbage collection process has started, the load variable having a value that is based at least in part on a number of garbage collection processes that are currently running on the system. Tuning further comprises creating a number of garbage collection threads based at least in part on the current value of the load variable and/or number of processors, where the garbage collection threads are used to perform at least a portion of at least one phase of the new garbage collection process. Tuning further comprises re-updating the load variable to reflect completion of the new garbage collection process.

Abstract: Described embodiments provide a memory manager for a network processor having a plurality of processing modules and a shared memory. The memory manager allocates blocks of the shared memory to requesting ones of the plurality of processing modules. A free block list tracks availability of memory blocks of the shared memory. A reference counter maintains, for each allocated memory block, a reference count indicating a number of access requests to the memory block by ones of the plurality of processing modules. The reference count is located with data at the allocated memory block. For subsequent access requests to a given memory block concurrent with processing of a prior access request to the memory block, a memory access accumulator (i) accumulates an incremental value corresponding to the subsequent access requests, (ii) updates the reference count associated with the memory block, and (iii) updates the memory block with the accumulated result.

Abstract: Methods and systems for coordinating provisions of storage service for clients are provided. For each storage provider of a set of storage providers, a service-provider database stores a metric characterizing a property of a service provided by the service provider. The storage providers are independently owned and operated relative to each other. The metrics are repeatedly updated. A selection engine repeatedly selects a service provider from the set of service providers to store a content object of a client of the content delivery system. The selection is based on the repeatedly updated metrics for the set of service providers. For each service provider selected by the selection engine to store the content object of the client, a service manager coordinates with the service provider such that the service provider stores the content object of the client.

Abstract: A pool, which is configured by multiple actual areas, is formed on the basis of two or more storage devices. A second storage control apparatus (DKC) determines, for each storage device, an unused capacity to be given to a first DKC with respect to each first DKC based on an unused capacity of each storage device and a request value of each storage device for each first DKC, and gives, for each first DKC, the unused capacity for each storage device determined with respect to the first DKC, to this first DKC. The request value of the storage device is based on a performance value, which is a value related to the performance of this storage device. The total capacity of multiple actual areas allocated to the virtual volumes by the first DKC is equal to or less than the unused capacity given with respect to each storage device.

Abstract: Allocation of virtual disk volumes of a size designated by the computer manager to a virtual computer and accessiblity from the virtual computer to the virtual disk voumes without requiring intervention by a hypervisor are to be achieved. In a computer, at least one virtual computer to be in execution on the computer, and a computer system in which the virtual computer has volumes for holding data, a virtualization mechanism has a virtual volume allocating unit and a virtual volume information supplying unit, and the virtual computer has a virtual volume driver for converting positional information on virtual volumes. Additionally, the virtualization mechanism holds the virtual volume information together with defining information for the virtual computer to which the virtual volumes have been allocated.

Abstract: A desirable number of segments for a multi-segment single error correcting (SEC) coding scheme is determined based on scrambling information for a memory. The desirable number of segments can be the minimum number of segments required to satisfy a masked write segmentation requirement and a multi-bit upset size requirement. In one aspect, the memory scrambling information can specify the different scrambling techniques employed by the memory (e.g., Input-Output (IO) cell scrambling, column scrambling, column twisting, strap distribution, etc.). Based on the scrambling information, a mapping between the logical structure and physical layout for the memory can be derived. The mapping can be used to determine the least number of segments needed to satisfy the masked write requirement and the multi-bit upset size requirement.

Abstract: A system, and computer usable program product for expanding memory size are provided in the illustrative embodiments. A desired size of an expanded memory and a first information about a workload in the data processing system are received. A size of a compressed memory pool to use with the memory to make the desired size of the expanded memory available is computed. A representation of the memory is configured, the representation of the memory appearing to be of a size larger than the size of the memory, the representation of the memory being the expanded memory, and the size of the representation being the size of the expanded memory. The expanded memory is made available such that the memory in the data processing system is usable by addressing the expanded memory.

Abstract: Methods, systems, and computer program products for operating an enterprise resource planning system. The method includes running a placeholder job in said enterprise resource planning system in response to a request from at least one client application for notification of at least one background processing event, wherein the placeholder job is executed in response to the at least one background processing event.

Abstract: A method and system writes data to a memory device including writing data to varying types of physical write blocks. The method includes receiving a request to write data for a logical block address within an LBA range to the memory device. Depending on whether the quantity of valid data in the memory device meets a predetermined criteria, the data is written to a specific chaotic block, a general chaotic block, or a mapped block. The mapped block is assigned for writing data for the LBA range, the specific chaotic block is assigned for writing data for contiguous LBA ranges including the LBA range, and the general chaotic block is assigned for writing data for any LBA range. Lower fragmentation and write amplification ratios may result by using this method and system.

Abstract: A method of formatting a data storage device that includes a plurality of flash memory chips includes monitoring a failure rate of memory blocks of one or more flash memory chips of a storage device that has a first usable size for user space applications, estimating a future usable size of the data storage device based on the monitored failure rate, and defining, via a host coupled to the data storage device, a second usable size of the data storage device for user space applications based on the monitored failure rate.

Abstract: Provided is a method for managing a memory storage region used by a processor. The processor is connected to the memory that stores data accessed while a task is being executed. The memory management method including the steps of: dividing the memory area of the memory into blocks having a plurality of different sizes; selecting a block having a size matching a size of the data accessed while the task is being executed; and storing the data accessed while the task is being executed in the selected block.

Abstract: A method for performing garbage collection on an object heap is described. In one embodiment, such a method includes performing a copy phase on an object heap by copying live objects from a source space to a destination space. An abort condition is generated when copying an object from the source space to the destination space fails due to insufficient space. In response to the abort condition, tracing work and reference updating associated with the copy phase are terminated. A mark phase is then initiated that marks live objects in the source space. This mark phase resumes tracing work and reference updating terminated by the copy phase in order to avoid or minimize the repetition of work performed by the copy phase. A corresponding computer program product and system are also described.

Abstract: Administering thermal distribution among memory modules in a computing system that includes temperature sensors, where each temperature sensor measures temperature of a memory module and thermal distribution is effected by: determining, in real-time by a user-level application in dependence upon the temperature measurements of the temperature sensors, whether a memory module is overheated; if a memory module is overheated and if a current call stack frame is stored on the overheated memory module, increasing, by the user-level application, a size of the current call stack frame to fill remaining available memory space on the overheated memory module, ensuring a subsequent call stack frame is stored on a different memory module.

Abstract: A method for implementing on-demand configuration of a logical volume, wherein the method monitors the amount of available storage capacity of the logical storage volume and determines whether the available storage capacity exceeds a predetermined threshold, such as a percentage of available logical storage space. If the method determines that the storage capacity of the logical storage volume is nearing full capacity, the method determines whether configured physical storage space is available. If the method determines that configured physical storage space is available, the method then reconfigures the logical storage volume to include the configured physical storage space. If configured physical storage space is not available, the method locates unconfigured physical storage space, configures the available physical storage space, and reconfigures the logical volume using the configured physical storage space.

Abstract: A method for performing garbage collection on an object heap is described. In one embodiment, such a method includes performing a copy phase on an object heap by copying live objects from a source space to a destination space. An abort condition is generated when copying an object from the source space to the destination space fails due to insufficient space. In response to the abort condition, tracing work and reference updating associated with the copy phase are terminated. A mark phase is then initiated that marks live objects in the source space. This mark phase resumes tracing work and reference updating terminated by the copy phase in order to avoid or minimize the repetition of work performed by the copy phase. A corresponding computer program product and system are also described.

Abstract: The present invention is directed to systems and methods for mapping a neighborhood of data to general registers of a processing element. Embodiments of the present invention provide techniques for mapping a neighborhood of data to general registers that are “neighborhood constrained” because the general register set is of insufficient size in one or more dimensions to fully store a desired neighborhood of data in a manner that maintains the positional arrangement of such data. However, a window access method is employed for mapping the neighborhood of data to the general register set, thereby enabling the neighborhood of data to be stored to the general register set in a manner that maintains the positional arrangement of such data as may be desired for performing nearest-neighbor types of operations by the processing element.

Abstract: A storage system having at least two storage apparatuses capable of partitioning an internal resource into logical partitions and managing the logical partitions, and which replicates data written into a primary volume of a primary storage apparatus as the replication source storage apparatus to a secondary volume of a secondary storage apparatus as the replication destination storage apparatus, including: a configuration information sending unit for sending configuration information of the logical partition, to which the primary volume belongs, to the secondary storage apparatus; and a logical partition setting unit for setting the configuration of the logical partition to which the secondary volume belongs based on the configuration information of the logical partition to which the primary volume belongs sent from the configuration information sending unit.

Abstract: A virtual memory management unit can implement various techniques for managing paging space. The virtual memory management unit can monitor a number of unallocated large sized pages and can determine when the number of unallocated large sized pages drops below a page threshold. Unallocated contiguous smaller-sized pages can be aggregated to obtain unallocated larger-sized pages, which can then be allocated to processes as required to improve efficiency of disk I/O operations. Allocated smaller-sized pages can also be reorganized to obtain the unallocated contiguous smaller-sized pages that can then be aggregated to yield the larger-sized pages. If allocated smaller-sized pages belonging to a second process cannot be de-allocated by reorganizing, the second process can be terminated to de-allocate the pages. Furthermore, content can also be compressed before being written to the paging space to reduce the number of pages that are to be allocated to processes.

Abstract: A method, system, and apparatus are directed towards selectively compressing data for transmission over a network. In one embodiment, a sending network device and receiving network device negotiates different compression modes to communicate data between them. An initial compression mode may be selected based on a network bandwidth. The sending network device then reads data, and compresses using the selected compression mode. The compressed data may then be written out. Ratios of compression and the write times are then employed to selectively adjust the compression mode for subsequent data compressions. In one embodiment, a compression ratio is also employed to determine whether to employ the selected compression mode, or to reduce the level of compression by using a different compression mode. The receiving network device having received information about the selected compression mode, then employs that compression mode to decompress the received data.

Abstract: The present invention provides an approach for SAN forecasting in a heterogeneous environment. Specifically, under the present invention capacity data on the heterogeneous environment is gathered. Capacity management techniques will then be used to analyze the SAN utilization, identify growth trends and patterns. Proactively, plans are made to account for these changes. Thereafter, a Capacity Planning Margin (CPM) will be applied to the forecast to reflect actual customer usage. The CPM adjusted forecasts will then be reviewed. Then, the SAN environment can be monitored by comparing actual vs. planned and return to adjust the forecast accordingly.

Abstract: Block data access is provided for an operating system by allocating a portion of solid-state memory of a data processing arrangement for use as a block storage device. A block device interface is created that provides access to the portion of solid-state memory via firmware of the data processing arrangement. The block device interface emulates an electromechanical data-storage device. The block device interface is presented to the operating system at a boot-time of the operating system and the block device interface is accessed using a block device driver of the operating system during the boot-time of the operating system. The block device driver emulates the electromechanical data-storage device to the operating system.

Abstract: A system and method are provided for pooling storage devices in a virtual library for performing a storage operation. A storage management device determines a storage characteristic of a plurality of storage devices with respect to performing a storage operation. Based on a storage characteristic relating to performing the storage operation, the storage management device associates at least two storage devices in a virtual library. The storage management device may continuously monitor the virtual library and detect a change in storage characteristics of the storage devices. When changes in storage characteristics are detected, the storage management device may change associations of the storage device in the virtual library.

Abstract: A semiconductor storage device includes a first nonvolatile memory to store user data of a file, a second nonvolatile memory to store management data of the file, the second nonvolatile memory being different in type from the first nonvolatile memory, and a controller to control read/write of data with respect to the first and second nonvolatile memories.

Abstract: Methods of method of managing memory power usage in a computing device having two or more memory modules. By monitoring a system working set size of the computing device, a determination can be made if all active memory modules are needed for the system working set size. If not all active memory modules are needed for the system working set size, one or more of the active memory modules can be selected for power down. By evacuating data from the selected one or more memory modules, placing the evacuated one or more memory modules in a power-down state, and removing the powered-down memory modules from the active memory of the computing device, memory power usage can be reduced.

Abstract: One embodiment includes method acts for detecting race conditions. The method includes beginning a critical section, during which conflicting reads and writes should be detected to determine if a race condition has occurred. This is performed by executing at a thread one or more software instructions to place a software lock on data. As a result of executing one or more software instructions to place a software lock on data, several additional acts are performed. In particular, the thread places a software lock on the data locking the data for at least one of exclusive writes or reads by the thread. And, at a local cache memory local to the thread, the thread enters the thread's memory isolation mode enabling local hardware buffering of memory writes and monitoring of conflicting writes or reads to or from the cache memory to detect reads or writes by non-lock respecting agents.

Abstract: Administering thermal distribution among memory modules in a computing system that includes temperature sensors, where each temperature sensor measures temperature of a memory module and thermal distribution is effected by: determining, in real-time by a user-level application in dependence upon the temperature measurements of the temperature sensors, whether a memory module is overheated; if a memory module is overheated and if a current call stack frame is stored on the overheated memory module, increasing, by the user-level application, a size of the current call stack frame to fill remaining available memory space on the overheated memory module, ensuring a subsequent call stack frame is stored on a different memory module.

Abstract: Disclosed are various embodiments including systems and methods relating to the management of heat load in a data center. An access frequency of a data object is estimated in a computing device. The data object is stored in at least one of a plurality of storage units. Each of the storage units comprises a plurality of solid-state storage devices in a proximal arrangement. The storing is based at least in part on the access frequency of the data object and a density of the arrangement of the solid-state storage devices within the at least one of the storage units.

Abstract: An improved non-volatile memory and logical block to physical block address translation method utilizing a cluster based addressing scheme is detailed. The translation of logical blocks/sectors to the physical blocks/sectors is necessary for a non-volatile memory to appear as a freely rewriteable device to a system or processor. Embodiments of the present invention utilize cluster based address translation to translate logical block addresses to physical block addresses, wherein each cluster contains a plurality of sequentially addressed logical blocks. This allows the use of a smaller RAM table for the address translation lookup and/or faster scanning of the memory device or memory subsystem for the matching cluster address. In one embodiment, a specially formatted cluster is utilized for frequently updated sectors/logical blocks, where the cluster stores a single logical block and a new sequential physical block of the cluster is written in turn with each update.

Abstract: A virtualization system, upon judging that a write operation from a higher-level device is an operation to write in the format of the virtual volume, even when the write position of the write operation is in a virtual area different from a virtual area to which an allocated actual area has been allocated, if there is an unused area in the allocated actual area, writes management information to the unused area according to the write operation, and if there is no unused area in the allocated actual area, newly allocates an unallocated actual area, and writes management information to the newly allocated actual area according to the write operation.