A server cluster is a group of servers that collaborate on a single system to provide users with increased availability. These clusters are used to minimise downtime and outages by allowing another server to take over in the event of an outage, a feature called redundancy. In this article, we will explain all about server clustering, which increases reliability and scalability of server systems..
What Is A Server Cluster?
A server cluster is a group of servers working together with a common IP address (the IP address is common through server and firewall configurations). Clustered servers are commonly used for servers that include various services such as file servers, print servers, and more commonly for required high-availablity services such as databases, and other critical services. A server cluster maintains the consistency of server services over time. It also ensures higher availability, proper load balancing, and system scalability.
In a server cluster, each of the participating server is called a node. Each server which has its own resources such as hard drive, RAM, and CPU to use. The reason for implementing such a configuration is so that if one server within the cluster fails, then the load is transferred to another server, without any downtime. Clusters thereofire are used to reduce downtime and outages.
Hvordan fungerer serverklyngning?
En samling af servere er knyttet til et enkelt system. Når en af disse servere fejler, omfordeles arbejdsbyrden til en anden server så kunden ikke oplever nedetid.
Klyngede servere bruges typisk til applikationer, der kræver hyppige dataopdateringer, idet fil-, print-, database- og messaging -servere er de mest almindelige klynger.
Samlet set giver klyngeservere klienter et højere tilgængelighedsniveau, pålidelighed og skalerbarhed, end nogen enkelt server kunne.
I et klynget servermiljø er hver server ansvarlig for ejerskabet og administrationen af sine egne enheder, samt at have en kopi af operativsystem (sammen med eventuelle applikationer eller tjenester), der bruges til at køre de andre servere i klyngen.
The servers in the cluster are configured to collaborate in order to increase data security and maintain the consistency of the cluster configuration over time.
Klyngemangel og afbrydelsesbeskyttelse
Den primære årsag til at bruge serverklynger er at undgå afbrydelser og nedetid. Som tidligere nævnt giver klyngede servere øget beskyttelse mod, at et helt netværk bliver mørkt under strømafbrydelse.
Clustered servers provide protection against three types of outages: Application or service failures, hardware or system failures, site failures.
Vi vil gå mere detaljeret over på denne type afbrud i de følgende afsnit, men kort sagt hjælper serverklynger med at beskytte mod afbrydelser forårsaget af softwarefejl, hardwarefejl og fremmede hændelser, der virker på det fysiske serverwebsted.
1. Fejl i en applikation eller tjeneste
Program- eller servicefejlbegivenheder omfatter alle afbrydelser, der opstår som følge af kritiske fejl, der involverer software eller tjenester, der er kritiske for serverens eller datacentrets drift.
Disse fejl kan skyldes en række forskellige faktorer, hvoraf de fleste er uundgåelige. Selvom de fleste servere har redundansforanstaltninger på plads for at forhindre denne type fejl, er applikations- eller servicefejl vanskelige at forudsige og planlægge.
Fordi serverovervågningsdata er komplekse, kan det være svært for serveradministratorer at identificere og løse potentielle problemer, før de forårsager et afbrydelse.
Selvom en årvågen, kyndig og proaktiv serveradministrator kan identificere og løse disse problemer, før de bliver et problem, kan ingen serveradministrator yde omfattende beskyttelse mod denne form for fejl.
2. Fejl i systemet eller hardwaren
Denne form for afbrydelse opstår som følge af fysiske hardwarefejl, som serveren kører på.
Disse afbrydelser kan skyldes en lang række faktorer og påvirkes af stort set alle typer komponenter, der er kritiske for driften af en server eller et datacenter.
Selvom serverkomponenters pålidelighed og funktionalitet støt forbedres, er ingen komponent immun mod fejl.
Overophedning, dårlig optimering eller simpelthen den komponent, der når slutningen af produktets levetid, kan alle forårsage denne fejl.
På grund af deres betydning for at holde serveren kørende, er processorer, fysisk hukommelse og harddiske blandt de mest tilbøjelige til fejl.
3. Problemer med webstedet
I de fleste tilfælde er webstedsfejl forårsaget af hændelser, der opstår uden for datacentermiljøet.
Selvom der er mange begivenheder, der kan forårsage et webstedsfejl i teorien, er de hændelser, der oftest er skyld i fejl på stedet, naturkatastrofer, der forårsager omfattende strømafbrydelser, såvel som dem, der kan skade hardwaren i datacenteret.
Selvom nogle naturkatastrofer ikke kan undgås med andet end omhyggeligt valg af sted, kan dem, der er forårsaget af strømafbrydelser og deres tilhørende komplikationer, afhjælpes ved at bruge redundansforanstaltninger såsom serverklynger.
Disse redundansforanstaltninger er afgørende for datacentre i områder, der er udsat for naturkatastrofer.
Selvom problemer, der potentielt kan føre til disse tre forskellige typer fejl, kan identificeres og løses, er redundansforanstaltninger såsom serverklynger den eneste måde at sikre næsten fuldstændig pålidelighed.
Serverklynger er en glimrende måde at sikre usvigelig ydeevne i datacentre, der kræver det hvert minut hver dag i året.
Klyngeservere er opdelt i tre typer
Serverklynger er klassificeret i tre typer baseret på, hvordan klyngesystemet (kaldet en node) er forbundet til den enhed, der er ansvarlig for lagring af konfigurationsdata.
En enkelt (eller standard) kvorumsklynge, en majoritetsnodesætklynge og en enkelt knudeklynge er de tre typer, og de diskuteres mere detaljeret nedenfor.
1. Kvorumsklynge med et enkelt (eller standard) kvorum
Denne klynge er den mest almindeligt anvendte og består af flere noder med en eller flere klyngediskarrays, der bruger en enkelt forbindelsesenhed (kaldet en bus).
Hver enkelt klyngediskarray i klyngen administreres og ejes af en enkelt server. Systemet, der bruges til at afgøre, om hver enkelt klynge er online og kompromisløs, omtales som titulært kvorum.
I praksis er enkelte kvorumsklynger ret enkle. Hver node har en "stemme", som den bruger til at meddele den centrale bus, at den er online og funktionel.
Klyngen vil forblive operationel, så længe mere end halvdelen af noderne i en enkelt kvorumsklynge er online. Hvis mere end halvdelen af noder i klyngen ikke reagerer, stopper klyngen med at fungere, indtil problemerne med de enkelte noder er løst.
2. Majority Node Set Cluster
Denne model adskiller sig, ligesom den forrige, ved at hver node har sin egen kopi af klyngens konfigurationsdata, som er konsistent på tværs af alle noder.
Denne model er bedst egnet til klynger med individuelle servere på forskellige geografiske placeringer.
Mens majoritetsnodesætklynger fungerer på samme måde som enkeltkvorumsklynger, adskiller den førstnævnte sig ved, at den ikke kræver, at en delt lagringsbus fungerer, fordi hver node gemmer en duplikat af kvorumdata lokalt.
Selvom dette ikke udelukker brugen af en delt bus helt, giver det mere fleksibilitet ved konfiguration af fjernservere.
3. Single Node Cluster
Denne model, som oftest bruges til test, har en enkelt knude. Enkeltknudeklynger bruges ofte som et værktøj til udvikling og forskning af klynge -applikationer, men deres anvendelighed er stærkt begrænset af deres mangel på failover.
Fordi de kun består af en node, gør fejlen i en enkelt node alle klyngegrupper ude af drift.
En kundeservicerepræsentant hos et lokalt datacenter eller en webhostingudbyder kan forklare forskellene mellem de tre modeller og hjælpe dig med at beslutte, hvilken der er bedst for din virksomhed.
Unless du har usædvanlige krav (eller er placeret på flere geografisk spredte steder), er Standard Quorum Cluster din bedste chance.
There are other names that are given to server clustering types, which we will discuss here.
4. High-Performance Server Clusters for High Availablity
Clusters with high availability (HA) are the best option for websites with a lot of traffic. For online stores or applications that require optimal, continuous performance from their critical systems, HA clusters could be used.
Because high availability clusters are based on redundant hardware and software, they help you avoid single points of failure. They are essential for failover, system backups, and load balancing. These devices are made up of several hosts that are able to take over in the event that a specific server fails or overloads, ensuring that there will be as little downtime as possible.
High Availability Server Architecture
There are two types of architecture for HA clusters: active-active and active-passive.
All nodes in an active-active cluster balance loads concurrently. An active-passive architecture, on the other hand, assigns all workloads to a primary node. A backup node is kept ready for any outages in the meantime.
Because it has the primary node's database on it, the secondary server is also referred to as a hot spare or hot standby. This is a less expensive implementation than active-active since the hot standby is prepared to take over in the event that a component fails.
High availability clusters facilitate easy scalability and increase your reliability. Not to mention, they provide strong infrastructure security and more effective maintenance. You can cut expenses, reduce downtime, and improve user experience with these clusters.
5. Load Balancing Clusters
Server farms called load balancing clusters divide up user requests among several active nodes. The three primary advantages are better workload distribution, redundancy assurance, and faster operations.
You can divide workloads among servers and separate functions with load balancing. This arrangement aids in optimizing resource usage. It employs load balancing software to assign requests, according to an algorithm, to various servers. Outgoing responses are also managed by the software.
Load balancers are used in a high availability cluster's active-active configuration. The load balancer is used by the HA cluster to respond to various requests and send them to separate servers. There are two possible distributions: symmetric and asymmetric, depending on the configuration data and computer performance.
The load balancer keeps track of the availability of nodes in an active-passive high availability cluster. A node that shuts down waits to send any more traffic until it is back up and running.
Additionally, you can use multiple links simultaneously thanks to load balancing architecture. When it comes to infrastructure that needs redundant communication, this feature is extremely helpful. Data centers and telecommunications companies, for instance, frequently use this architecture. Better scalability, cost reduction, and high-bandwidth data transfer optimization are the main advantages.
6. Clustered and High-Performance Storage
Supercomputers, another name for high-performance clusters, are machines with greater capacity, dependability, and performance. They are most commonly used by businesses with resource-intensive workloads.
Many PCs linked to the same network make up a high-performance server cluster. To process data faster, you can link several of these clusters to the network's data storage hubs. Put differently, seamless performance and fast data transfers are provided along with high-performance data storage clusters.
Artificial intelligence (AI) and the Internet of Things (IoT) are two major applications for these clusters. To power complex projects like live streaming, storm prediction, and patient diagnosis, they process massive amounts of real-time data. These characteristics of high-performance cluster applications are also advantageous for media, research and financial services,
7. Storage with clustering capabilities
Clustered storage typically involves a minimum of two storage servers. They enable you to enhance the performance, input/output (I/O) capabilities, and reliability of your system. Depending on the specific needs of your business and the amount of data you need to store, you have the option to choose between a tightly or loosely coupled architecture.
An architecture that is tightly coupled focuses on primary storage. It organizes data into smaller blocks distributed among nodes.
On the other hand, a self-contained, loosely coupled architecture provides greater flexibility. However, it does not have the capability to store data across nodes. In a loosely coupled architecture, the performance and capacity of the data storage node become the determining factors. Scaling with new nodes is not possible in a loosely coupled architecture.
How can server clusters enhance scalability?
Server clusters enable horizontal scalability within the system. IT teams have the flexibility to effortlessly incorporate additional nodes to handle the desired volume of traffic or data transmissions.
In addition, the presence of additional servers enhances scalability. Just one server is sufficient to handle all business processes. Having additional servers in the configuration provides greater flexibility and scalability in terms of resources, leading to enhanced fault tolerance and performance.
How can server clusters achieve load balancing?
Server clusters ensure efficient workload distribution by automatically transferring excess tasks to other nodes in the system. This can be achieved through either an active-active or active-passive configuration.
When the incoming traffic or data processing queries surpass the capacity of one server, they can be transferred to another cluster server that is available. Usually, this transition can occur in two different ways — through manual or automatic means.
Using manual clusters can be problematic as it requires configuring a node to the same data IP address, resulting in downtime. Even a brief period of downtime can have significant financial or operational consequences. However, with automatic clusters, you have the ability to pre-configure software settings. This cluster setup performs the server switch automatically.
How can server clusters ensure high availability?
It is ideal to use multiple web and app nodes to ensure hardware redundancy. This type of architecture is commonly referred to as a high availability cluster. Ensuring uninterrupted operation in the event of a component failure is crucial. This is particularly evident when the operating system experiences a failure, lacking redundancy in a single server. With no site failures, your users will remain unaware of any server crashes.
HA clusters use an active-active server configuration to seamlessly swap resources without any service interruption. While this configuration is more efficient, it usually comes at a higher cost compared to an active-passive (or hot standby) configuration, as all nodes in the system need to remain active.
Hvorfor skal du gruppere servere?
Redundans er nøglen til en sikker it -infrastruktur. Oprettelse af en klynge af servere på et enkelt netværk giver maksimal redundans og sikrer, at en enkelt fejl ikke lukker hele dit netværk, hvilket gør dine tjenester utilgængelige og koster din virksomhed vitale indtægter.
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