An object store is a low-level abstraction of storage. Instead of providing a block-level view of a storage device, an object store allows to access it by a more abstract way, namely via objects. Being on top of a storage device, it is responsible for storage management. It can be used as a stand-alone light-weight file system when only basic storage management is necessary. Moreover it can act as a supporting layer for full-featured file systems in order to lighten their management overhead. Only a few object store solutions exist. These object stores are, however, not suitable for these use cases. For example no user interface is provided or it is too difficult to use. The development of some object stores has ceased, so that the code of the implementation is not available anymore. That is why a new object store is needed facing those problems. In this thesis a low-level and extent-based object store is designed and implemented. It is able to perform fully-functional storage management. For this, appropriate data structures are designed, for example, so-called inodes and extents. These are file system concepts that are adapted to the object store design and implementation. The object store uses the memory mapping technique for memory management. This technique maps a device into the virtual address space of a process, promising efficient access to the data. An application programming interface is designed allowing easy use and integration of the object store. This interface provides two features, namely synchronization and transactions. Transactions allow to batch several input/output requests into one operation. Synchronization ensures that data is written immediately after the write request. The object store implementation is object-oriented. Each data structure constitutes a programming unit consisting of a set of data types and methods. The performance of the object store is evaluated and compared with well-known file systems. It shows excellent performance results, although it constitutes a prototype. The transaction feature is found to be efficient. It increases the write performance by a factor of 50 when synchronization of data is activated. It especially outperforms the other file systems concerning metadata performance. A high metadata performance is a crucial criterion when the object store is used as a supporting storage layer in the context of parallel file systems.

@mastersthesis{DIAEOALEOS13,
	author	 = {Sandra Schröder},
	title	 = {{Design, Implementation, and Evaluation of a Low-Level Extent-Based Object Store}},
	advisors	 = {Michael Kuhn},
	year	 = {2013},
	month	 = {12},
	school	 = {Universität Hamburg},
	howpublished	 = {{Online \url{https://wr.informatik.uni-hamburg.de/_media/research:theses:sandra_schroeder_design_implementation_and_evaluation_of_a_low_level_extent_based_object_store.pdf}}},
	type	 = {Master's Thesis},
	abstract	 = {An object store is a low-level abstraction of storage. Instead of providing a block-level view of a storage device, an object store allows to access it by a more abstract way, namely via objects. Being on top of a storage device, it is responsible for storage management. It can be used as a stand-alone light-weight file system when only basic storage management is necessary. Moreover it can act as a supporting layer for full-featured file systems in order to lighten their management overhead. Only a few object store solutions exist. These object stores are, however, not suitable for these use cases. For example no user interface is provided or it is too difficult to use. The development of some object stores has ceased, so that the code of the implementation is not available anymore. That is why a new object store is needed facing those problems. In this thesis a low-level and extent-based object store is designed and implemented. It is able to perform fully-functional storage management. For this, appropriate data structures are designed, for example, so-called inodes and extents. These are file system concepts that are adapted to the object store design and implementation. The object store uses the memory mapping technique for memory management. This technique maps a device into the virtual address space of a process, promising efficient access to the data. An application programming interface is designed allowing easy use and integration of the object store. This interface provides two features, namely synchronization and transactions. Transactions allow to batch several input/output requests into one operation. Synchronization ensures that data is written immediately after the write request. The object store implementation is object-oriented. Each data structure constitutes a programming unit consisting of a set of data types and methods. The performance of the object store is evaluated and compared with well-known file systems. It shows excellent performance results, although it constitutes a prototype. The transaction feature is found to be efficient. It increases the write performance by a factor of 50 when synchronization of data is activated. It especially outperforms the other file systems concerning metadata performance. A high metadata performance is a crucial criterion when the object store is used as a supporting storage layer in the context of parallel file systems.},
}