I think its mostly a question of initial scale and HR capability. If you have the talent and processes in place to manage the cluster, then go for it. If you are starting out, then simplicity and ease of management will lead to stability, go fault tolerant.
My experience is in SME's or in small to medium sized units of larger businesses, that try to maximize their internal capability at the lowest possible cost.
In almost every case, clusters (based on Windows) were far more prone to problems than fault tolerant servers. The lack of reliability came most often from the increased hassle, maintenance, and complexity of the clusterred (especially fibre) solutions.
While they had, on paper, more fault tolerance and could theoretically provide greater availability, the factors I laid out above acted as a drag on their uptime. So much so, that fault tolerant servers or small storage devices (especially Netapp) often provided comparable ACTUAL uptime figures.
As a bonus, the simplicity of the infrastructure allowed much greater flexibility when approaching problems.
Unless your infrastructure is already of "enterprise" scale, clustering is not a great option. As a first step into a large scale infrastructure, I would definitely pursue fault tolerance first.
Slashdot Mirror
I think its mostly a question of initial scale and HR capability. If you have the talent and processes in place to manage the cluster, then go for it. If you are starting out, then simplicity and ease of management will lead to stability, go fault tolerant.
My experience is in SME's or in small to medium sized units of larger businesses, that try to maximize their internal capability at the lowest possible cost. In almost every case, clusters (based on Windows) were far more prone to problems than fault tolerant servers. The lack of reliability came most often from the increased hassle, maintenance, and complexity of the clusterred (especially fibre) solutions. While they had, on paper, more fault tolerance and could theoretically provide greater availability, the factors I laid out above acted as a drag on their uptime. So much so, that fault tolerant servers or small storage devices (especially Netapp) often provided comparable ACTUAL uptime figures. As a bonus, the simplicity of the infrastructure allowed much greater flexibility when approaching problems. Unless your infrastructure is already of "enterprise" scale, clustering is not a great option. As a first step into a large scale infrastructure, I would definitely pursue fault tolerance first.