One of the biggest drawbacks to the cloud is that your cloud service provider can withdraw your hosting or whatever service you are paying for at any time.
The first and most obvious cloud drawback of course, is downtime. No cloud provider can truthfully claim to be 100% reliable. Accidents do happen. Perhaps your cloud service provider had an IT failure, a power outage, was the victim of a DDOS attack, or some other unforeseen event. That can sever, at least briefly, the crucial link between yourself and the cloud.
However, one thing I have noticed that has been left undiscussed is that your cloud provider may terminate your service at any time. I think that the risk of a sudden termination is higher than say, downtime (modern clouds have very low downtime nowadays). The reasons for doing so could be mundane, or they could be quite less pleasant.
An example of a mundane reason may be that you were accidentally late in paying a bill. In that case, you would be unable to access your cloud services until the bill was paid and the service provider processed payment then re-activated your service. That can take a couple of days, depending on the provider, which can be a critical period of days. It’s not uncommon for such a temporary outage to come, and sadly, outages tend to happen at the most critical times. Even more infuriatingly, sometimes the cloud service provider themselves makes a billing mistake even if you as a customer did pay on time.
An example of something less pleasant is vendor lock-in. Imagine if you are totally dependent on a cloud provider and they suddenly raise prices. They demand “pay up or else!” You may find yourself with little choice to pay up, even if the fee is exorbitant, less you lose your critical files.
By signing the end user agreement (which many people did not read), you are at the mercy of whatever terms the cloud service provider has made. Often there are hidden clauses that can be very anti-customer. An example is mandatory arbitration, and the arbitrator is assuredly biased against you.
No cloud provider is running their business as a charity, as Aditya Agarwal once noted. There are no non-profit or government cloud providers that are running at cost. That margin is money out of your pocket. Alternatively, if the services are funded through something such as advertising, there are other drawbacks that you should be aware of.
Be sure to back up!
To begin with, what you do have on the cloud and what can be backed up, you should periodically backup.
This certainly has huge limitations, because it is the very cloud services you are paying for to begin with! However, it is better than nothing. Terminations, outages, and other problems are an inherent risk of the cloud. Even if they were not, there are other linkages that are very vulnerable, such as your internet connection.
Key takeaway, this industry is all about trust
There is a big trust element in using the cloud that I do not believe that many users truly recognize. While a small percentage of sophisticated users truly understand the implications, I do not believe that the general public truly understands.
We have become totally dependent on the cloud. That means that we are trusting our cloud provider to act in a manner that has integrity. If you are reading this website, there is a trust element too that I have made. An example, the cloud can result in total vendor lock-in, because you as the end user are completely reliant on the cloud service provider for their services. If they adopt abusive business practices or raise their service charges to unreasonable levels, you have few options but to pay up. The cloud provider effectively has you hostage.
By putting your data onto the cloud, you are effectively trusting your cloud provider not to undertake such business practices. There is also the loss in expertise that you could have considered building in-house or learning yourself personally. In the long run, in many cases, that may very well have been superior to the option of outsourcing to the cloud. Often simply integrating into the cloud takes a lot of time and effort, then maintaining the information takes even more money on top of any fees charged by the cloud.
I say this to you, as a reader not to discourage you from using the cloud, but to truly understand the trade-offs and the sacrifices. There are very real vulnerabilities that have not been discussed enough I think in the hype around the cloud. It is only through understanding these that you can make an intelligent decision.