Until recently, the decision which storage device is most suitable, in aspects of costs, capacity, performance and reliability has been an easy choice. Only hard disk devices offered requested properties. Nowadays rapid development of flash storage technology, makes these devices competitive or even more attractive. The great advantage of flash storage is, apart from lower energy consumption and insensitivity against mechanical shocks, the much lower access time. Compared with hard disks, flash devices can access data about a hundred times faster. This feature enables a significant performance benefit for random I/O operations. Unfortunately, the situation at present is that HDDs provide a much bigger capacity at considerable lower prices than flash storage devices, and this fact does not seem to be changing in the near future.Considering also the wide-spread use of HDDs, the continuing increase of storage density and the associated increase of sequential I/O performance, the incentive to use HDDs will continue. For this reason, a way to combine both storage technologies seems beneficial. From the view of a file system, meta data is often accessed randomly and very small, in contrast a logical file might be large and is often accessed sequentially. Therefore, in this thesis a file system is designed and implemented which places meta data on an USB-flash device and data on an HDD. The design also considers, how meta data operations can be optimized for a cheep low-end USB flash device, which provide flash media like fast access times but also characteristic low write rates, caused by the block-wise erase-before-write operating principle. All measured file systems show a performance drop for meta data updates on this kind of flash devices, compared with their behavior on HDD. Therefore the design focused on the possibility to map coherent logical name space structures (directories) close to physical media characteristics (blocks). To also check impacts by writes of data sizes equal or smaller then the selected block size, the option to write only full blocks or current block fill rates was given. The file system was implemented in the user space and operate through the FUSE interface. Despite of the overhead caused by this fact, the performance of write associated meta data operations (like create/remove) was better or equal than of those file systems used for benchmark comparison.

@misc{CFSMEPCFFS10,
	author	 = {Leszek Kattinger},
	title	 = {{Crossmedia File System MetaFS -- Exploiting Performance Characteristics from Flash Storage and HDD}},
	advisors	 = {Julian Kunkel and Olga Mordvinova},
	year	 = {2010},
	month	 = {03},
	school	 = {Ruprecht-Karls-Universität Heidelberg},
	howpublished	 = {{Online \url{https://wr.informatik.uni-hamburg.de/_media/research:theses:leszek_kattinger_crossmedia_file_system_metafs_exploiting_performance_characteristics_from_flash_storage_and_hdd.pdf}}},
	type	 = {Bachelor's Thesis},
	abstract	 = {Until recently, the decision which storage device is most suitable, in aspects of costs, capacity, performance and reliability has been an easy choice. Only hard disk devices offered requested properties. Nowadays rapid development of flash storage technology, makes these devices competitive or even more attractive. The great advantage of flash storage is, apart from lower energy consumption and insensitivity against mechanical shocks, the much lower access time. Compared with hard disks, flash devices can access data about a hundred times faster. This feature enables a significant performance benefit for random I/O operations. Unfortunately, the situation at present is that HDDs provide a much bigger capacity at considerable lower prices than flash storage devices, and this fact does not seem to be changing in the near future.Considering also the wide-spread use of HDDs, the continuing increase of storage density and the associated increase of sequential I/O performance, the incentive to use HDDs will continue. For this reason, a way to combine both storage technologies seems beneficial. From the view of a file system, meta data is often accessed randomly and very small, in contrast a logical file might be large and is often accessed sequentially. Therefore, in this thesis a file system is designed and implemented which places meta data on an USB-flash device and data on an HDD. The design also considers, how meta data operations can be optimized for a cheep low-end USB flash device, which provide flash media like fast access times but also characteristic low write rates, caused by the block-wise erase-before-write operating principle. All measured file systems show a performance drop for meta data updates on this kind of flash devices, compared with their behavior on HDD. Therefore the design focused on the possibility to map coherent logical name space structures (directories) close to physical media characteristics (blocks). To also check impacts by writes of data sizes equal or smaller then the selected block size, the option to write only full blocks or current block fill rates was given. The file system was implemented in the user space and operate through the FUSE interface. Despite of the overhead caused by this fact, the performance of write associated meta data operations (like create/remove) was better or equal than of those file systems used for benchmark comparison.},
}