Multi-cloud does not mean a special product, it describes a cloud architecture model specified by the IT strategy. Multi in this context means that multiple clouds are used, but from different providers. This can be multiple, at least two, public clouds or private clouds. The separate cloud providers are used simultaneously to provide infrastructure (IaaS), platform (PaaS) and software services (SaaS). Operating a multi-cloud architecture often arises by accident already, for example, because different public cloud services were gradually purchased for different departments and functions. However, there are also many companies that consciously rely on the multi-cloud strategy in order not to have to commit to one cloud provider or if data losses or downtimes are to be prevented. For example, if a best-price strategy or a best-fit strategy for cloud use has been developed, a multi-cloud architecture may make sense. In practice, this can look as follows: Computing resources are outsourced to public cloud providers, Azure or AWS for example. These can be platform services (PaaS), for example databases or compute instances as IaaS. In parallel, special AI or BIG Data applications are obtained from the Google Cloud. Now you are already operating a multi-cloud environment.
A hybrid cloud infrastructure is characterized by the fact that several clouds of different types are operated. It is therefore a mixture of public and private cloud environments. Here, the private cloud can be operated at an external cloud service provider or in the company's own on-site data center. In many companies, hybrid IT is created as part of a comprehensive cloud strategy that wants to operate different components locally, public or privat. In order for this to result in a homogeneous operating model for the user, interconnectivity between the infrastructures is necessary. This means that the business services distributed across the cloud environments are connected as seamlessly as possible. This allows business processes to be orchestrated and workloads to be migrated between environments. Data can be moved between platforms and shared across applications. In practice, this can look like this: A database can be run in a public cloud, while the associated web applications, for example for the development, are deployed in the private cloud. In this way, employees can access the data they need from anywhere.
Hybrid clouds are always a mixture of a private cloud and at least one public cloud service. The existing private cloud is often operated locally, on-premises, and combined with cloud resources in a public cloud. The business services are linked together in such a way that a combined unit is created for the user. On the other hand, in a multi-cloud a private cloud element does not necessarily have to be in use. The local data center, if already in place, continues to operate unaffected. The multi-cloud architecture is built in parallel. The individual cloud environments thus established at the various cloud computing providers exist without any claim to connectivity to the private data center or to each other. If a company relies exclusively on public cloud offerings for its multi-cloud strategy, it requires an explicit data strategy. Only in this way can availability and security requirements be guaranteed to prevent problems. However, this also applies to a hybrid cloud environment because data is also hosted in public clouds here. A hybrid approach allows key database servers, monitoring and management processes or authentication resources to be hosted in the private cloud.
A hybrid cloud becomes a multi-cloud when more than one public cloud service is combined with private cloud resources. So by extension, any hybrid cloud can also be classified as a multi-cloud by definition. The strategy switch is also possible in reverse. Companies can operate a hybrid cloud as part of a multi-cloud strategy by using both public and private clouds and linking workloads between the two environments.
The pros and cons for the respective cloud operating form depend to a large extent on the requirements in the company as well as on the company's own cloud strategy. So it is almost individual evaluation criteria that you should draw on. There is no off-the-shelf cloud architecture per se. It is therefore not so easy to generalize which positive or negative aspects the respective cloud architecture brings with it. Nevertheless, the two strategies can be contrasted and compared on the basis of their operational impact and characteristics:
|Flexibility||Very high flexibility, as there is no need to be dependent on a cloud provider. A "best of breed" approach can be taken, in which it can be decided which platform best suits one's own workloads.||If required, the hybrid cloud can flexibly scale the computing power, storage space or other services of the private cloud with services from the public cloud. In this way, it is possible to react quickly and flexibly. When operating your own data center, physical computers and networks are very expensive and time-consuming. There is not much flexibility here.|
|Reliability||In public clouds, the customer systems are distributed across several data centers. This reduces the company's own risk of failure in the event of a breakdown at the cloud provider.||Responsibility for security and back-ups for data from the private cloud lies with the company itself, even if third-party providers make the infrastructure available.|
|Scalability||Cloud services can often be added in a matter of minutes with public cloud providers. They can also be quickly reduced if the capacity is no longer needed. However, the scalability options depend on the terms of the contract.||The scaling options are limited to the cloud resources operated in a public cloud. When operating a private cloud, legacy resources often exist which cannot be easily ported and are therefore difficult to scale. In addition, physical components have to be built up or be reduced.|
|Independence||A Vendor log-in can be avoided because there are enough alternative partners if a cloud provider reaches its limits. There is also greater scope for a best-price strategy compared to the hybrid cloud.||Independence is limited to the cloud services which are hosted in the public cloud. Since you have to ensure interconnectivity between the environments, there are not unlimited options to operate.|
|Data protection and security||Data privacy and security standards can be ensured by ISO certificates of the cloud providers. However, the various individual concepts and providers do not result in a uniform data protection and data security concept. This can lead to inconsistencies and difficulties in reconciling compliance guidelines throughout the company. It can become critical when cloud services are operated outside Germany or the EU.||The operating model must be integrated into the existing data protection and data security concept. Since critical data can be hosted locally and within the organization, data protection guidelines can be easily implemented. However, the responsibility lies with the organization's own IT staff or a managed service provider. Non-critical services can be operated in the public cloud.|
|Data access||If you want to distribute the business services among the various cloud providers and resources, the number of necessary interfaces quickly increases. Sources of error can quickly arise during data transfer.||Your own on-site data center can also be set up as a private cloud, so that employees can access their data from anywhere. However, interfaces to the resources from the public cloud are necessary so that the business services function properly.|
|Complexity||With hundreds of individual cloud services, management becomes a huge task for the IT. After all, managing an IT service with different resources at various cloud providers quickly makes things very complex.
Although there are cloud management platforms that assist with administration, the contractual details require specialist personnel.
|Hybrid clouds require more complex management than when IT is run purely in the company's own data center. The two cloud worlds, private and public, are seamlessly connected and therefore offer simpler management and unification of the IT environment. Business processes must be analyzed in detail in advance and divided up according to the cloud types.|
|Cost transparency||Many contracts also mean many price models and contract terms. However, volume discounts are often not usable because the demand from one provider is too low. This makes cost transparency of all cloud services and cloud resources very complex. Not only tools are needed, but also cloud experts who are responsible for cost transparency and correct billing/accounting in the company.||Since IT services can consist of local as well as cloud resources, cost transparency is very complex and a management tool becomes necessary. In the case of a hybrid cloud, it is important to estimate the costs of whether future IT services will be operated on-premises or in the cloud. For this, IT managers and finance managers must work more closely together in the long term.|
|Management||The IT service responsibility lies with the own company and therefore also the monitoring of the cloud resources regarding contract modalities or capacity utilization. This requires software for consolidated multi-cloud management to monitor and control all cloud services in bundled form. Depending on the rented cloud service, tasks such as maintenance work, updates or additional security measures are not required.||Management is more complex because private cloud as well as public cloud aspects have to be taken into account. Here a consolidated management console can provide a better overview of all business services, regardless of whether connected resources are operated on-premises or in the cloud.|