With its inherent data isolation and multiple availability issues, multi-tenancy is a legacy cloud computing architecture that cannot stand the test of time. Multi-instance cloud architecture on the other hand, can solve the drawbacks of multi-tenancy.
1. True data isolation: multi-instance cloud architecture is not built on large centralised database software and infrastructure. Instead, it allocates a unique database to each customer. This prevents data co-mingling, simplifies maintenance, and makes delivering upgrades and resolving issues much easier because it can be done on a one-on-one basis.
2. Safeguards against hardware failures and other unexpected outages: The cloud provider actually deploys separate hardware and software stacks for each customer. There is some sharing of infrastructure pieces, such as network architecture, load balancers, and common network components. But these are segmented into distinct zones so that the failure of one or more devices does not affect more than a few customers. This enables the creation of redundancy at every layer. For example, at the internet borders, a vendor might have multiple border routers that connect to several tier- one providers on many different private circuits, direct connections, and on different pieces of fiber.
3. One's data loss will not result in your data loss: multi-instance, unlike multi-tenancy, does not run on a master file system that services all customers. You can scale out pieces of hardware - stack them on top of each other like LEGO blocks. Each block services no more than a few customers, so one hardware crash cannot affect all the blocks. And because replication is automatic, the secondary side is immediately accessible. This is extremely important for the approach to disaster recovery. Permanent data loss is a risk inherent to all multi-tenant architectures, making external disaster recovery sites no longer viable options. True, there are sites that a vendor can fall to if the active side fails. But they are only tested a few times a year and only used if an extreme situation arises. If that happens, they risk failing under load. When that happens, data is lost forever. That risk virtually disappears in a multi-instance environment.
When you partner with a cloud provider that bases its platform on a multi-instance architecture, you're moving into your own house. Your data is isolated, a fully replicated environment provides extremely high availability, and upgrades on the schedule you set, not the provider. Cloud architecture matters because you're in control, and better protected when disaster strikes.
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