HPC-Dictionary - Revision history

Christian-griebel-aab2@tu-darmstadt.de: /* Shared filesystems */

2019-10-01T14:32:47Z

Shared filesystems

Daniel-schurhoff-de23@rwth-aachen.de at 13:07, 3 September 2019

2019-09-03T13:07:33Z

Christian-griebel-aab2@tu-darmstadt.de: /* Copy Node */

2019-07-12T14:43:25Z

Copy Node

Christian-griebel-aab2@tu-darmstadt.de: /* Scheduler */

2019-06-03T13:54:02Z

Scheduler

Christian-griebel-aab2@tu-darmstadt.de at 13:53, 3 June 2019

2019-06-03T13:53:47Z

Christian-griebel-aab2@tu-darmstadt.de: /* Scheduler */

2019-06-03T13:52:27Z

Scheduler

Christian-griebel-aab2@tu-darmstadt.de at 13:51, 3 June 2019

2019-06-03T13:51:21Z

Christian-griebel-aab2@tu-darmstadt.de: /* File System */

2019-06-03T13:47:11Z

File System

Christian-griebel-aab2@tu-darmstadt.de at 13:46, 3 June 2019

2019-06-03T13:46:20Z

Christian-griebel-aab2@tu-darmstadt.de: /* NUMA */

2019-06-03T13:37:06Z

NUMA

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 ==== Shared filesystems ====
-... can be read and written to by all nodes in the cluster. A file created by any node can immediately be seen by any other node.<br />
+... can be read and written to by ''all compute nodes'' in the cluster. A file created by any node can immediately be seen by any other node. Sometimes also known as ''global'' or ''cluster file system''.<br />
-Examples are the Network File System NFS, or Lustre or GPFS (a.k.a. "Spectrum Scale").
+Examples are the Network File System NFS, Lustre or IBM's GPFS (a.k.a. "Spectrum Scale").
 == Environment Variables ==

← Older revision		Revision as of 13:07, 3 September 2019
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		+	[[Category:Basics]]
	== Unix ==		== Unix ==

@@ Line 63: / Line 63: @@
 === Copy Node ===
-Copy nodes are reserved for transfering data to or from a cluster. They usually offer a better connection than other nodes and minimize the disturbance of other users on the system. Depending on the facility, software installed on these nodes may differ from other ones due to their restricted use case, though not every facility chooses to install a designated copy node at all. As an alternative [[#Login Node|login nodes]] may be used to move data between systems.
+Copy nodes are reserved for transferring data to or from a cluster. They usually offer a better connection than other nodes and minimize the disturbance of other users on the system. Depending on the facility, software installed on these nodes may differ from other ones due to their restricted use case, though not every facility chooses to install a designated copy node at all. As an alternative [[#Login Node|login nodes]] may be used to move data between systems.
 === Frontend Node ===

@@ Line 128: / Line 128: @@
 == Scheduler ==
-The [Scheduling_Basics|scheduler] is the administrative heart of any HPC cluster. Like a dispatcher, it receives batch jobs submitted by the users, arbitrating and coordinating their placement and execution on various compute nodes.<br />
+The [[Scheduling_Basics|scheduler]] is the administrative heart of any HPC cluster. Like a dispatcher, it receives batch jobs submitted by the users, arbitrating and coordinating their placement and execution on various compute nodes.<br />
 The batch script to be submitted can contain directives (pragmas) to control job placement (eg. "put this job on any node with at least 16 cores and 32 GByte main memory" or "put this job on any node with a graphics card (GPU)".

@@ Line 128: / Line 128: @@
 == Scheduler ==
-The scheduler is the administrative heart of any HPC cluster. Like a dispatcher, it receives batch jobs submitted by the users, arbitrating and coordinating their placement and execution on various compute nodes.<br />
+The [Scheduling_Basics|scheduler] is the administrative heart of any HPC cluster. Like a dispatcher, it receives batch jobs submitted by the users, arbitrating and coordinating their placement and execution on various compute nodes.<br />
 The batch script to be submitted can contain directives (pragmas) to control job placement (eg. "put this job on any node with at least 16 cores and 32 GByte main memory" or "put this job on any node with a graphics card (GPU)".

← Older revision		Revision as of 13:51, 3 June 2019
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	==== Weak Scalability ====		==== Weak Scalability ====
	By involving more and more processor cores, the application can tackle '''larger''' problems (size), though you can no longer achieve reduced runtimes on the '''same''' problem (size).		By involving more and more processor cores, the application can tackle '''larger''' problems (size), though you can no longer achieve reduced runtimes on the '''same''' problem (size).
		+
		+	== Scheduler ==
		+	The scheduler is the heart of any HPC cluster. It receives batch jobs submitted by the users, arbitrating and coordinating their placement and execution on various compute nodes.<br />
		+	The batch script to be submitted can contain directives (pragmas) to control job placement (eg. "put this job on any node with at least 16 cores and 32 GByte main memory" or "put this job on any node with a graphics card (GPU)".

@@ Line 6: / Line 6: @@
 The file system allows for a hierarchical (directory or folder) structure of all data (files). On Unix-based systems, the top directory is <code>/</code> (the "root" directory), from which all other directories branch off into a tree-like structure.
-Most of the time you will be working in directories starting with <code>/home/<username></code>, which represents the user's home directory. All directories starting with <code>/home/<username></code> can be freely modified at will by the owner.
+Most of the time you will be working in directories starting with <code>/home/<username></code>, which represents the user's home directory. All directories and files below <code>/home/<username></code> can be freely modified at will by the owner.
 ==== Local filesystems ====

@@ Line 5: / Line 5: @@
 == File System ==
-The file system describes the directory structure of an operating system. On Unix-based systems the top most directory is <code>/</code>, which is called the root directory. As the name may suggest the file system is organized hierarchically (like a tree) from there on out. Most of the time you will be working in directories starting with <code>/home/<username></code>, which represents the user's home directory. All directories starting with <code>/home/<username></code> can freely be modified to the will of the user.
+The file system allows for a hierarchical (directory or folder) structure of all data (files). On Unix-based systems, the top directory is <code>/</code> (the "root" directory), from which all other directories branch off into a tree-like structure.
-== Environment Variable ==
+==== Local filesystems ====
-An environment variable is a dynamic object on a computer, which stores a value. On Unix-based operating systems you can:
+==== Shared filesystems ====
 * set the value of a variable with: <code>export <variable-name>=<value></code>
 * read the value of a variable with: <code>echo $<variable-name></code>
-Environment variables can be referenced by software (or the user) to get or set information about the system. Down below are a few examples of environment variables, which might give you an idea for their use and usefulness.
+Environment variables can be referenced by software (or the user) to get or set information about the system or the environment. See below for a few examples of environment variables, which might give you an idea for their use and usefulness.
 {| class="wikitable"

@@ Line 100: / Line 100: @@
 == NUMA ==
-'''N'''on-'''U'''niform '''M'''emory '''A'''ccess is a hardware architecture by which the main memory chips are not connected equally to all sockets. For example, socket 1 has a direct connection to banks 1, 3, 5 and 7, whereas socket 2 is closely connected to banks 0, 2, 4  and 8. Accessing the non-local memory chips incurs a (small) performance penalty.
+'''N'''on-'''U'''niform '''M'''emory '''A'''ccess is a hardware architecture by which the main memory chips are not connected equally to all sockets. For example, socket 1 has a direct connection to banks 1 to 8, whereas socket 2 is closely connected to banks 8-16. Accessing the non-local memory chips (via the other socket) incurs a (small) performance penalty.
 == Scalability ==