Ganglia (software)
Encyclopedia
Ganglia is a scalable distributed system monitor
tool for high-performance computing systems such as clusters and grids
. It allows the user to remotely view live or historical statistics (such as CPU
load averages or network utilization) for all machines that are being monitored.
-based listen/announce protocol to monitor state within clusters and uses a tree of point-to-point connections amongst representative cluster nodes to federate clusters and aggregate their state. It leverages widely used technologies such as XML
for data representation, XDR
for compact, portable data transport, and RRDtool
for data storage and visualization. It uses carefully engineered data structures and algorithms to achieve very low per-node overheads and high concurrency. The implementation is robust, has been ported to an extensive set of operating systems and processor architectures, and is currently in use on over 500 clusters around the world. It has been used to link clusters across university campuses and around the world and can scale to handle clusters with 2000 nodes.
The ganglia system comprises two unique daemons, a PHP
-based web front-end, and a few other small utility programs.
Gmond has four main responsibilities:
Each gmond transmits in information in two different ways:
es for access control and can be specified using multiple IP addresses for failover. The latter capability is natural for aggregating data from clusters since each gmond daemon contains the entire state of its cluster.
view of the XML tree, it has evolved into a system that keeps a colorful history of all collected data.
The Ganglia web front-end caters to system administrator
s and users. For example, one can view the CPU
utilization over the past hour, day, week, month, or year. The web front-end shows similar graphs for memory usage, disk usage, network statistics, number of running processes, and all other Ganglia metrics.
The web front-end depends on the existence of the gmetad which provides it with data from several Ganglia sources. Specifically, the web front-end will open the local port 8651 (by default) and expects to receive a Ganglia XML tree. The web pages themselves are highly dynamic; any change to the Ganglia data appears immediately on the site. This behavior leads to a very responsive site, but requires that the full XML tree be parsed on every page access. Therefore, the Ganglia web front-end should run on a fairly powerful, dedicated machine if it presents a large amount of data.
The Ganglia web front-end is written in the PHP
scripting language, and uses graphs generated by gmetad to display history information. It has been tested on many flavours of Unix
(primarily Linux
) with the Apache webserver
and the PHP 4.1 module.
System monitor
A system monitor is a hardware- or software- based system used to monitor resources and performance in a computer system.Software monitors occur more commonly, sometimes as a part of a widget engine. These monitoring systems are often used to keep track of system resources, such as CPU usage and...
tool for high-performance computing systems such as clusters and grids
Grid computing
Grid computing is a term referring to the combination of computer resources from multiple administrative domains to reach a common goal. The grid can be thought of as a distributed system with non-interactive workloads that involve a large number of files...
. It allows the user to remotely view live or historical statistics (such as CPU
Central processing unit
The central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...
load averages or network utilization) for all machines that are being monitored.
Ganglia
It is based on a hierarchical design targeted at federations of clusters. It relies on a multicastMulticast
In computer networking, multicast is the delivery of a message or information to a group of destination computers simultaneously in a single transmission from the source creating copies automatically in other network elements, such as routers, only when the topology of the network requires...
-based listen/announce protocol to monitor state within clusters and uses a tree of point-to-point connections amongst representative cluster nodes to federate clusters and aggregate their state. It leverages widely used technologies such as XML
XML
Extensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....
for data representation, XDR
External Data Representation
External Data Representation is a standard data serialization format, for uses such as computer network protocols. It allows data to be transferred between different kinds of computer systems. Converting from the local representation to XDR is called encoding. Converting from XDR to the local...
for compact, portable data transport, and RRDtool
RRDtool
RRDtool aims to handle time-series data like network bandwidth, temperatures, CPU load, etc...
for data storage and visualization. It uses carefully engineered data structures and algorithms to achieve very low per-node overheads and high concurrency. The implementation is robust, has been ported to an extensive set of operating systems and processor architectures, and is currently in use on over 500 clusters around the world. It has been used to link clusters across university campuses and around the world and can scale to handle clusters with 2000 nodes.
The ganglia system comprises two unique daemons, a PHP
PHP
PHP is a general-purpose server-side scripting language originally designed for web development to produce dynamic web pages. For this purpose, PHP code is embedded into the HTML source document and interpreted by a web server with a PHP processor module, which generates the web page document...
-based web front-end, and a few other small utility programs.
Ganglia Monitoring Daemon (gmond)
Gmond is a multi-threaded daemon which runs on each cluster node you want to monitor. Installation does not require having a common NFS filesystem or a database back-end, install special accounts or maintain configuration files.Gmond has four main responsibilities:
- Monitor changes in host state.
- Announce relevant changes.
- Listen to the state of all other ganglia nodes via a unicast or multicast channel.
- Answer requests for an XML description of the cluster state.
Each gmond transmits in information in two different ways:
- UnicastUnicastright|200pxIn computer networking, unicast transmission is the sending of messages to a single network destination identified by a unique address.-Addressing methodologies:...
ing or MulticastMulticastIn computer networking, multicast is the delivery of a message or information to a group of destination computers simultaneously in a single transmission from the source creating copies automatically in other network elements, such as routers, only when the topology of the network requires...
ing host state in external data representation (XDR)External Data RepresentationExternal Data Representation is a standard data serialization format, for uses such as computer network protocols. It allows data to be transferred between different kinds of computer systems. Converting from the local representation to XDR is called encoding. Converting from XDR to the local...
format using UDPUser Datagram ProtocolThe User Datagram Protocol is one of the core members of the Internet Protocol Suite, the set of network protocols used for the Internet. With UDP, computer applications can send messages, in this case referred to as datagrams, to other hosts on an Internet Protocol network without requiring...
messages. - Sending XML over a TCPTransmission Control ProtocolThe Transmission Control Protocol is one of the core protocols of the Internet Protocol Suite. TCP is one of the two original components of the suite, complementing the Internet Protocol , and therefore the entire suite is commonly referred to as TCP/IP...
connection.
Ganglia Meta Daemon (gmetad)
Federation in Ganglia is achieved using a tree of point-to-point connections amongst representative cluster nodes to aggregate the state of multiple clusters. At each node in the tree, a Ganglia Meta Daemon (gmetad) periodically polls a collection of child data sources, parses the collected XML, saves all numeric, volatile metrics to round-robin databases and exports the aggregated XML over a TCP sockets to clients. Data sources may be either gmond daemons, representing specific clusters, or other gmetad daemons, representing sets of clusters. Data sources use source IP addressIP address
An Internet Protocol address is a numerical label assigned to each device participating in a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing...
es for access control and can be specified using multiple IP addresses for failover. The latter capability is natural for aggregating data from clusters since each gmond daemon contains the entire state of its cluster.
Ganglia PHP Web Front-end
The Ganglia web front-end provides a view of the gathered information via real-time dynamic web pages. Most importantly, it displays Ganglia data in a meaningful way for system administrators and computer users. Although the web front-end to ganglia started as a simple HTMLHTML
HyperText Markup Language is the predominant markup language for web pages. HTML elements are the basic building-blocks of webpages....
view of the XML tree, it has evolved into a system that keeps a colorful history of all collected data.
The Ganglia web front-end caters to system administrator
System administrator
A system administrator, IT systems administrator, systems administrator, or sysadmin is a person employed to maintain and operate a computer system and/or network...
s and users. For example, one can view the CPU
Central processing unit
The central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...
utilization over the past hour, day, week, month, or year. The web front-end shows similar graphs for memory usage, disk usage, network statistics, number of running processes, and all other Ganglia metrics.
The web front-end depends on the existence of the gmetad which provides it with data from several Ganglia sources. Specifically, the web front-end will open the local port 8651 (by default) and expects to receive a Ganglia XML tree. The web pages themselves are highly dynamic; any change to the Ganglia data appears immediately on the site. This behavior leads to a very responsive site, but requires that the full XML tree be parsed on every page access. Therefore, the Ganglia web front-end should run on a fairly powerful, dedicated machine if it presents a large amount of data.
The Ganglia web front-end is written in the PHP
PHP
PHP is a general-purpose server-side scripting language originally designed for web development to produce dynamic web pages. For this purpose, PHP code is embedded into the HTML source document and interpreted by a web server with a PHP processor module, which generates the web page document...
scripting language, and uses graphs generated by gmetad to display history information. It has been tested on many flavours of Unix
Unix
Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
(primarily Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
) with the Apache webserver
Apache HTTP Server
The Apache HTTP Server, commonly referred to as Apache , is web server software notable for playing a key role in the initial growth of the World Wide Web. In 2009 it became the first web server software to surpass the 100 million website milestone...
and the PHP 4.1 module.