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  1. node

  2. IPv6 address Solicited-node multicast address • The least significant 24 bits of the solicited-node multicast address group ID are filled with the least significant 24 bits of the interface's unicast or anycast address. These addresses allow link-layer address resolution via Neighbor Discovery Protocol (NDP) on the link without disturbing all nodes on the local network. A host is required to join a Solicited-Node multicast group for each of its configured unicast or anycast addresses.

  3. Hybrid fibre-coaxial Fiber optic nodes • The optical coupler combined with the optical receiver forms a node.

  4. Hybrid fibre-coaxial Fiber optic nodes • The optical portion of the network provides a large amount of flexibility. If there are not many fiber-optic cables to the node, wavelength division multiplexing can be used to combine multiple optical signals onto the same fiber. Optical filters are used to combine and split optical wavelengths onto the single fiber. For example, the downstream signal could be on a wavelength at 1310 nm and the return signal could be on a wavelength at 1550 nm.

  5. Device file Node creation • Nodes are created by the mknod system call. The command-line program for creating nodes is also called mknod. Nodes can be moved or deleted by the usual filesystem system calls (rename, unlink) and commands (mv, rm). When passed the option -R or -a while copying a device node, the cp -l command creates a new device node with the same attributes of the original.

  6. Device file Node creation • Some Unix versions include a script named makedev or MAKEDEV to create all necessary devices in the directory /dev. It only makes sense on systems whose devices are statically assigned major numbers (e.g. by means of hardcoding it in their kernel module).

  7. Anycast Local and global nodes • the AS is added a few more times) to make the path longer so that a local node announcement is preferred over a global node announcement.

  8. Computer network Network nodes • Apart from the physical communications media described above, networks comprise additional basic hardware building blocks, such as network interface controller cards (NICs), repeaters, hubs, bridges, switches, routers, and firewalls.

  9. Mono (software) - MonoDevelop • MonoDevelop is a free GNOME integrated development environment primarily designed for C# and other .NET languages such as Nemerle, Boo, and Java (via IKVM.NET), although it also supports languages such as C, C++, Python, Java, and Vala. MonoDevelop was originally a port of SharpDevelop to Gtk#, but it has since evolved to meet the needs of Mono developers. The IDE includes class management, built-in help, code completion, Stetic (a GUI designer), project support, and an integrated debugger.

  10. Mono (software) - MonoDevelop • The MonoDoc browser provides access to API documentation and code samples. The documentation browser uses wiki-style content management, allowing developers to edit and improve the documentation.

  11. Persistent data structure - Fat Node • In order to navigate through the structure, each original field value in a node has a version stamp of zero.

  12. Persistent data structure - Complexity of Fat Node • For access time, we must find the right version at each node as we traverse the structure

  13. IBM Sequoia - Node architecture • Sequoia is a Blue Gene/Q design, building off previous Blue Gene designs. It consists of 96 racks containing 98,304 compute nodes [1024/rack]. The compute nodes are 16-core PowerPC A2 processor chips with 16 GB of DDR3 memory each. Thus the system contains in total 1,572,864 processor cores [96*1024*16] with 1.5 PiB memory. It covers an area of about 3,000 square feet (280 m2). The computer nodes are interconnected in a 5-dimensional torus topology.

  14. inode • In computing, an inode (index node) is a data structure found in many Unix file systems. Each inode stores all the information about a file system object (file, device node, socket, pipe, etc.). It does not store the file's data content and file name except for certain cases in modern file systems.

  15. inode - Etymology • The reason for designating these as "i" nodes is unknown. When asked, Unix pioneer Dennis Ritchie replied:

  16. inode - Etymology • In truth, I don't know either. It was just a term that we started to use. "Index" is my best guess, because of the slightly unusual file system structure that stored the access information of files as a flat array on the disk, with all the hierarchical directory information living aside from this. Thus the i-number is an index in this array, the i-node is the selected element of the array. (The "i-" notation was used in the 1st edition manual; its hyphen was gradually dropped.)

  17. inode - Etymology • Also Maurice J. Bach writes:

  18. inode - Etymology • The term inode is a contraction of the term index node and is commonly used in literature on the UNIX system.

  19. inode - Etymology • —Maurice J. Bach, The Design of the Unix Operating System, 1986

  20. inode - Details • A file system relies on data structures about the files, beside the file content. The former is called metadata—data that describes data. Each file is associated with an inode, which is identified by an integer number, often referred to as an i-number or inode number.

  21. inode - Details • Inodes store information about files and directories (folders), such as file ownership, access mode (read, write, execute permissions), and file type. On many types of file system implementations, the maximum number of inodes is fixed at file system creation, limiting the maximum number of files the file system can hold. A typical allocation heuristic for inodes in a file system is one percent of total size.

  22. inode - Details • The inode number indexes a table of inodes in a known location on the device; from the inode number, the file system driver portion of the kernel can access the contents of the inode, including the location of the file allowing access to the file.

  23. inode - Details • A file's inode number can be found using the ls -i command. The ls -i command prints the i-node number in the first column of the report.

  24. inode - Details • Some Unix-style file systems such as ReiserFS omit an inode table, but must store equivalent data in order to provide equivalent capabilities. The data may be called stat data, in reference to the stat system call that provides the data to programs.

  25. inode - Details • Unix directories are lists of association structures, each of which contains one filename and one inode number.

  26. inode - Details • The file system driver must search a directory looking for a particular filename and then convert the filename to the correct corresponding inode number.

  27. inode - Details • The operating system kernel's in-memory representation of this data is called struct inode in Linux. Systems derived from BSD use the term vnode, with the v of vnode referring to the kernel's virtual file system layer.

  28. inode - POSIX inode description • The POSIX standard mandates filesystem behavior that is strongly influenced by traditional UNIX filesystems. Regular files must have the following attributes:

  29. inode - POSIX inode description • The file mode which determines the file type and how the file's owner, its group, and others can access the file.

  30. inode - POSIX inode description • Additional system and user flags to further protect the file (limit its use and modification).

  31. inode - POSIX inode description • A link count telling how many hard links point to the inode.

  32. inode - POSIX inode description • Pointers to the disk blocks that store the file's contents (see inode pointer structure).

  33. inode - POSIX inode description • The stat system call retrieves a file's inode number and some of the information in the inode.

  34. inode - Implications • Files can have multiple names. If multiple names hard link to the same inode then the names are equivalent; i.e., the first to be created has no special status. This is unlike symbolic links, which depend on the original name, not the inode (number).

  35. inode - Implications • An inode may have no links. An unlinked file is removed from disk, and its resources are freed for reallocation but deletion must wait until all processes that have opened it finish accessing it. This includes executable files which are implicitly held open by the processes executing them.

  36. inode - Implications • It is typically not possible to map from an open file to the filename that was used to open it. The operating system immediately converts the filename to an inode number then discards the filename. This means that the getcwd() and getwd() library functions search the parent directory to find a file with an inode matching the working directory, then search that directory's parent, and so on until reaching the root directory. SVR4 and Linux systems maintain extra information to make this possible.

  37. inode - Implications • Historically, it was possible to hard link directories

  38. inode - Implications • A file's inode number stays the same when it is moved to another directory on the same device, or when the disk is defragmented which may change its physical location. This also implies that completely conforming inode behavior is impossible to implement with many non-Unix file systems, such as FAT and its descendants, which don't have a way of storing this invariance when both a file's directory entry and its data are moved around.

  39. inode - Implications • For this reason, when updating programs, best practice is to delete the old executable first and create a new inode for the updated version, so that any processes executing the old version may proceed undisturbed.

  40. inode - Practical considerations • Many computer programs used by system administrators in UNIX Operating Systems often designate files with inode numbers. Examples include popular disk integrity checking utilities such as the fsck or pfiles. Thus, the need naturally arises to translate inode numbers to file pathnames and vice versa. This can be accomplished using the file finding utility find with the -inum option, or the ls command with the proper option (-i on POSIX compliant platforms).

  41. inode - Practical considerations • It is possible to use up a device's set of inodes. When this happens, new files cannot be created on the device, even though there may be free space available. For example, a mail server may have many small files that don't fill up the disk, but use many inodes to point to the numerous files.

  42. inode - Practical considerations • Filesystems (such as JFS or XFS) escape this limitation with extents and/or dynamic inode allocation, which can 'grow' the filesystem and/or increase the number of inodes.

  43. inode - Inlining • As an inode's size is limited, this only works for very small files.

  44. Compute Node Linux • Compute Node Linux (CNL) is a runtime environment based on the Linux kernel for the Cray XT3, Cray XT4, Cray XT5, Cray XT6, and Cray XE6 supercomputer systems based on SUSE Linux Enterprise Server. CNL forms part of the Cray Linux Environment. As of November 2011 systems running CNL were ranked 3rd, 6th and 8th among the fastest supercomputers in the world.

  45. MonoDevelop - History • In late 2003, a few developers from the Mono community began migrating SharpDevelop, a successful .NET open source IDE from System.Windows.Forms on Windows to Gtk# on Linux. Being an early fork of SharpDevelop, MonoDevelop architecturally differs from recent SharpDevelop releases.

  46. MonoDevelop - History • Over time, the MonoDevelop project was absorbed into the rest of the Mono project and is actively maintained by Xamarin and the Mono community. Since Mono 1.0 Beta 2, MonoDevelop is bundled with Mono releases.

  47. MonoDevelop - MonoDevelop on non-Linux platforms • MonoDevelop on FreeBSD is likewise supported only by the FreeBSD community.

  48. MonoDevelop - MonoDevelop in the Unity3D game development environment • MonoDevelop is also the primary IDE for the Unity3D game development environment. The current version that ships with Unity3D (v4.2.0f4) is MonoDevelop 2.8.2.

  49. Node (computer science) • Software is said to have a node graph architecture when its organization consists of interlinked nodes.

  50. Node (computer science) - Pseudocode implementation examples • Here, three such nodes form a singly linked list of length 3: