One of the facets of Cloud Computing is elasticity – that is the ability to both grow and shrink on-demand, following the peaks and troughs in compute requirements of an application. Therefore, one challenge for the cloud provider is to ensure that there is enough ‘slack’ available to meet the demands of those peaks.
Having slack means that there is spare capacity – or to put it another way, idle resources that could otherwise be put to useful work. IBM, along with other providers, offer customers a way to take advantage of this slack through transient virtual servers.
What’s a Transient Virtual Server?
Something which is transient is short lived and that’s the idea of Transient Virtual Servers. Essentially, they are available for as long as there is spare capacity – as soon as that capacity disappears then the transient virtual server is taken down and normally without any notice.
What’s the benefit of a Transient Virtual Server?
In a word, cost. Because the lifetime of a transient virtual server is largely unpredictable and can end without notice, cloud providers typically offer rock-bottom pricing for them. If your workload fits the pattern of a transient virtual server, why pay full price?
And the downsides?
Well, the obvious downside is that they may not always be available when you want them. You’ll only be able to provision them when capacity is available and once they are running, you’re not entirely sure for how long. Again though, if your workload fits the pattern of a transient virtual server, why pay full price?
What workloads are best suited to transient virtual servers?
Obviously workloads that are critical are not suited to transient virtual servers. Nobody would suggest running a production, business critical system on them. However, any number of batch processes, development and test activities, as well as application scaling tests may well be suitable and will of course benefit from lower costs. Any workload that does not need permanent compute resources or can be run on a flexible schedule may well suit transient virtual servers and enjoy the cost benefits.
Great! What do IBM offer?
You can order transient virtual servers on the IBM Cloud, from our data centres across the globe, dependent on there being sufficient spare capacity. Provisioning is done in the normal way, through the catalog. Pretty much the only difference between specifying a transient virtual server to a regular virtual server is that you can only attach SAN-based storage to them.
The server will persist either for as long as you need it, or when those data centre resources are needed again, whichever is sooner. Capacity from transient virtual servers will be reclaimed on a ‘last on, last off’ basis and remember they can be reclaimed without notice.