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In computer storage, fragmentation is a phenomenon in which storage space, such as computer memory or a hard drive, is used inefficiently, reducing capacity or performance and often both. The exact consequences of fragmentation depend on the specific system of storage allocation in use and the particular form of fragmentation.
Operating systems may use different slab sizes and internal layouts depending on the size of the objects to be stored. The reason for the large slabs having a different layout from the small slabs is that it allows large slabs to pack better into page-size units, which helps with fragmentation.
An example of the fragmentation of a protocol data unit in a given layer into smaller fragments. IP fragmentation is an Internet Protocol (IP) process that breaks packets into smaller pieces (fragments), so that the resulting pieces can pass through a link with a smaller maximum transmission unit (MTU) than the original packet size.
There is a utility, iDefrag, by Coriolis Systems available since OS X 10.3. On traditional Mac OS defragmentation can be done by Norton SpeedDisk and TechTool Pro. WAFL in NetApp's ONTAP 7.2 operating system has a command called reallocate that is designed to defragment large files. XFS provides an online defragmentation utility called xfs_fsr.
File system fragmentation is more problematic with consumer-grade hard disk drives because of the increasing disparity between sequential access speed and rotational latency (and to a lesser extent seek time) on which file systems are usually placed. [8] Thus, fragmentation is an important problem in file system research and design.
The operating system provides an interface between an application program and the computer hardware, so that an application program can interact with the hardware only by obeying rules and procedures programmed into the operating system. The operating system is also a set of services which simplify development and execution of application programs.
The sequence number for the entire DATA stream (used in fragmentation for reassembly). Stream identifier Identifier of the stream that this data chunk belongs to. Stream sequence number Identifier of the sequence number for the message in this stream. If a message is fragmented then this value is maintained for all fragments. Payload protocol ...
Software DSM systems can be implemented in an operating system, or as a programming library and can be thought of as extensions of the underlying virtual memory architecture. When implemented in the operating system, such systems are transparent to the developer; which means that the underlying distributed memory is completely hidden from the ...