Red Hat CLUSTER SUITE FOR ENTERPRISE LINUX 5.1 Uživatelský manuál stáhnout pdf (Strana 6)

Introduction to Linux Clustering

3 Advantages and reasons for clustering

Clustering provides a number of advantages over traditional standalone server configurations. First

there are a number of obvious ones:

● High-Availability of system services.

The cluster management software will handle service failures and will quickly bring up the

service on alternate hardware.

● Better utilisation of system resources.

Services can be spread around all the nodes – heavy nodes can be lightened by moving

services away, lightly loaded nodes can have more services started on them.

When you combine Xen with clustering, even more options become available, as you can

split one node into many dozens of nodes.

● Optimisation of disk resources.

Rather than having lots of small local disks, storage can be centralised or distributed across

all machines making better use of the storage available.

There are also some other useful advantages:

● Usability of older hardware or whitebox hardware

IT departments like to purchase new servers from a big name vendor like IBM or Dell, who

will then provide 5 years of hardware replacement and service. However, once this 5 year

period is over, the hardware is no longer supported and the customer either has to carry their

own spare parts (which can be too expensive for a small organisation) or upgrade to newer

hardware, which requires time, money and effort to migrate all the data and applications.

With clustering, if the hardware fails, another node will take up the work – so companies can

build their IT infrastructure around older hardware or custom built hardware saving a lot of

money.

Some hosting providers may even decide to leave old host in the cluster and to just keep

adding new ones, and only pull out the old ones once they fail or once they reach an age

where they are uneconomical to keep running.

● Faster more efficient system administration

In server farms where all the servers are configured individually, it can often be quite hard to

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Red Hat CLUSTER SUITE FOR ENTERPRISE LINUX 5.1 Uživatelský manuál Strana 6