UnixWare NonStop Clusters
Encyclopedia
NonStop Clusters was an add-on package for SCO
UnixWare
that allowed creation of fault-tolerant single-system image
cluster
s of machines running UnixWare. NSC was one of the first commercially available highly available
clustering solutions for commodity hardware
.
cluster:
Process migration:Processes started on any node in the cluster could be migrated to any other node. Migration could be either manual or automatic (for load balancing).
Single process space:All processes were visible from all nodes in the cluster. The standard Unix process management commands (ps, kill and so on) were used for process management.
Single root:All files and directories were available from all nodes of the cluster
Single I/O space:All I/O devices were available from any node in the cluster. The normal device naming convention was modified to add a node number to all device names. For example the second serial port on node 3 would be
Single IPC space:The standard UnixWare IPC mechanisms (shared memory
, semaphore
s, message queues, Unix domain socket
s) were all available for communication between processes running on any node.
Cluster virtual IP address:NSC provided a single IP address for access to the cluster from other systems. Incoming connections were load-balanced
between the available cluster nodes.
The NSC system was designed for high availability—all system services were either redundant or would fail-over from one node to another in the advent of a node crash. The disk subsystem was either accessible from multiple nodes (using a Fibre Channel
SAN or dual-ported SCSI
) or used cross-node mirroring
in a similar fashion to DRBD
.
by Locus Computing Corporation
based on their Transparent Network Computing technology. During the lifetime of the project Locus were acquired by Platinum Technology
Inc. The NSC team and product were then transferred to Tandem.
Initially NSC was developed for the Compaq
Integrity XC
packaged cluster, consisting of between two and six Compaq ProLiant
servers and one or two Compaq ServerNet
switches to provide the cluster interconnect inter-node communication path. In this form NSC was commercialized by Compaq and only supported on qualified hardware from Compaq, and later Fujitsu-Siemens.
In 2000 NSC was modified to allow standard Fast Ethernet
and later Gigabit Ethernet
switches as the cluster interconnect and commercialized by SCO
as UnixWare NonStop Clusters 7.1.1+IP.
This release of NSC was available on commodity PC hardware, although SCO recommended that systems with more than two nodes used the ServerNet interconnect.
After the sale of the SCO Unix business to Caldera Systems it was announced that the long term goal was to integrate the NSC product into the base UnixWare code
but this was not to be, Caldera Systems ceased distribution of NSC, replacing it by the Reliant HA clustering solution and in May 2001 Compaq announced that it would release a GPLed version of the NSC code, which eventually became OpenSSI
.
SCO
-Codes:* .sco, the proposed national internet TLD for Scotland* Country code for Scotland* Scots language * Aktau Airport in Kazakhstan, IATA code.-Companies:* Santa Cruz Operation, a company founded in 1979...
UnixWare
UnixWare
UnixWare is a Unix operating system maintained by The SCO Group . UnixWare is typically deployed as a server rather than desktop. Binary distributions of UnixWare are available for x86 architecture computers. It was originally released by Univel, a jointly owned venture of AT&T's Unix System...
that allowed creation of fault-tolerant single-system image
Single-system image
In distributed computing, a single system image cluster is a cluster of machines that appears to be one single system. The concept is often considered synonymous with that of a distributed operating system, but a single image may be presented for more limited purposes, just job scheduling for...
cluster
Cluster (computing)
A computer cluster is a group of linked computers, working together closely thus in many respects forming a single computer. The components of a cluster are commonly, but not always, connected to each other through fast local area networks...
s of machines running UnixWare. NSC was one of the first commercially available highly available
High-availability cluster
High-availability clusters are groups of computers that support server applications that can be reliably utilized with a minimum of down-time. They operate by harnessing redundant computers in groups or clusters that provide continued service when system components fail...
clustering solutions for commodity hardware
Commodity computing
Commodity computing is to use large numbers of already available computing components for parallel computing to get the greatest amount of useful computation at low cost. It is computing done in commodity computers as opposed to high-cost supermicrocomputers or boutique computers...
.
Description
NSC provided a full single-system imageSingle-system image
In distributed computing, a single system image cluster is a cluster of machines that appears to be one single system. The concept is often considered synonymous with that of a distributed operating system, but a single image may be presented for more limited purposes, just job scheduling for...
cluster:
Process migration:Processes started on any node in the cluster could be migrated to any other node. Migration could be either manual or automatic (for load balancing).
Single process space:All processes were visible from all nodes in the cluster. The standard Unix process management commands (ps, kill and so on) were used for process management.
Single root:All files and directories were available from all nodes of the cluster
Single I/O space:All I/O devices were available from any node in the cluster. The normal device naming convention was modified to add a node number to all device names. For example the second serial port on node 3 would be
/dev/tty01h.3. A partition on a SCSI disk on node 2 might be /dev/rdsk/n2c3b0t4d0s3.Single IPC space:The standard UnixWare IPC mechanisms (shared memory
Shared memory
In computing, shared memory is memory that may be simultaneously accessed by multiple programs with an intent to provide communication among them or avoid redundant copies. Depending on context, programs may run on a single processor or on multiple separate processors...
, semaphore
Semaphore (programming)
In computer science, a semaphore is a variable or abstract data type that provides a simple but useful abstraction for controlling access by multiple processes to a common resource in a parallel programming environment....
s, message queues, Unix domain socket
Unix domain socket
A Unix domain socket or IPC socket is a data communications endpoint for exchanging data between processes executing within the same host operating system. While similar in functionality to...
s) were all available for communication between processes running on any node.
Cluster virtual IP address:NSC provided a single IP address for access to the cluster from other systems. Incoming connections were load-balanced
Load balancing (computing)
Load balancing is a computer networking methodology to distribute workload across multiple computers or a computer cluster, network links, central processing units, disk drives, or other resources, to achieve optimal resource utilization, maximize throughput, minimize response time, and avoid...
between the available cluster nodes.
The NSC system was designed for high availability—all system services were either redundant or would fail-over from one node to another in the advent of a node crash. The disk subsystem was either accessible from multiple nodes (using a Fibre Channel
Fibre Channel
Fibre Channel, or FC, is a gigabit-speed network technology primarily used for storage networking. Fibre Channel is standardized in the T11 Technical Committee of the InterNational Committee for Information Technology Standards , an American National Standards Institute –accredited standards...
SAN or dual-ported SCSI
SCSI
Small Computer System Interface is a set of standards for physically connecting and transferring data between computers and peripheral devices. The SCSI standards define commands, protocols, and electrical and optical interfaces. SCSI is most commonly used for hard disks and tape drives, but it...
) or used cross-node mirroring
Disk mirroring
In data storage, disk mirroring or RAID1 is the replication of logical disk volumes onto separate physical hard disks in real time to ensure continuous availability...
in a similar fashion to DRBD
DRBD
DRBD is a distributed storage system for the GNU/Linux platform. It consists of a kernel module, several userspace management applications and some shell scripts and is normally used on high availability clusters...
.
History
NSC was developed for TandemTandem Computers
Tandem Computers, Inc. was the dominant manufacturer of fault-tolerant computer systems for ATM networks, banks, stock exchanges, telephone switching centers, and other similar commercial transaction processing applications requiring maximum uptime and zero data loss. The company was founded in...
by Locus Computing Corporation
Locus Computing Corporation
Locus Computing Corporation was formed in 1982 by Gerald J. Popekto commercialize the technologies developed for the LOCUS distributed operating system at UCLA...
based on their Transparent Network Computing technology. During the lifetime of the project Locus were acquired by Platinum Technology
Platinum Technology
Platinum Technology Inc. was founded by Andrew Filipowski in 1987 to market and support deployment of database management software products and the applications enabled by database management technology and render related services...
Inc. The NSC team and product were then transferred to Tandem.
Initially NSC was developed for the Compaq
Compaq
Compaq Computer Corporation is a personal computer company founded in 1982. Once the largest supplier of personal computing systems in the world, Compaq existed as an independent corporation until 2002, when it was acquired for US$25 billion by Hewlett-Packard....
Integrity XC
packaged cluster, consisting of between two and six Compaq ProLiant
Proliant
ProLiant is a brand of server computers that was originally developed and marketed by Compaq. After Compaq merged into Hewlett-Packard , HP continued to develop and market these servers as HP ProLiant. ProLiant systems lead the x86 server market in terms of units and revenue...
servers and one or two Compaq ServerNet
ServerNet (Tandem)
- History :ServerNet is a switched fabric communications link primarily used in proprietary computers made by Tandem Computers, Compaq, and HP. Its features include good scalability, clean fault containment, error detection and failover. The ServerNet architecture specification defines a connection...
switches to provide the cluster interconnect inter-node communication path. In this form NSC was commercialized by Compaq and only supported on qualified hardware from Compaq, and later Fujitsu-Siemens.
In 2000 NSC was modified to allow standard Fast Ethernet
Fast Ethernet
In computer networking, Fast Ethernet is a collective term for a number of Ethernet standards that carry traffic at the nominal rate of 100 Mbit/s, against the original Ethernet speed of 10 Mbit/s. Of the fast Ethernet standards 100BASE-TX is by far the most common and is supported by the...
and later Gigabit Ethernet
Gigabit Ethernet
Gigabit Ethernet is a term describing various technologies for transmitting Ethernet frames at a rate of a gigabit per second , as defined by the IEEE 802.3-2008 standard. It came into use beginning in 1999, gradually supplanting Fast Ethernet in wired local networks where it performed...
switches as the cluster interconnect and commercialized by SCO
SCO
-Codes:* .sco, the proposed national internet TLD for Scotland* Country code for Scotland* Scots language * Aktau Airport in Kazakhstan, IATA code.-Companies:* Santa Cruz Operation, a company founded in 1979...
as UnixWare NonStop Clusters 7.1.1+IP.
This release of NSC was available on commodity PC hardware, although SCO recommended that systems with more than two nodes used the ServerNet interconnect.
After the sale of the SCO Unix business to Caldera Systems it was announced that the long term goal was to integrate the NSC product into the base UnixWare code
but this was not to be, Caldera Systems ceased distribution of NSC, replacing it by the Reliant HA clustering solution and in May 2001 Compaq announced that it would release a GPLed version of the NSC code, which eventually became OpenSSI
OpenSSI
OpenSSI is an open source single-system image clustering system. It allows a collection of computers to be treated as one large system, allowing applications running on any one machine access to the resources of all the machines in the cluster....
.