Updated: November 2020
At Coeo we are seeing increasing numbers of customers take their first steps towards modernising their data platforms by moving workloads to the public cloud. Here is our quick guide to the options available:
When running on premises, organisations have two options; running SQL Server
directly on the hardware or virtualising the environment. Despite some reservations
against doing this, most customers we work with have found that the flexibility
virtualisation provides far outweighs the small performance penalty they pay (usually
in the region of about 1-2% CPU and Memory).
Virtualisation allows the customer to create logical separation of the environment.
This means that they have more options in terms of running different versions of the
platform to support an estate that is going through a modernisation process.
It also means that where we may have had a single large cluster while running
directly on the hardware, we are now able to virtualise onto more virtual servers. This
allows us to create a logical separation between parts of the platform and make the
impact of maintenance or unexpected outage less for the users.
It is now rare for customers to solely upgrade on-premises, we are seeing our
customers take a hybrid approach to modernisation. Whilst the ultimate destination
for many of the applications is Software as a Service (SaaS), the applications that
differentiate the business tend to go to PaaS in the absence of a suitable SaaS
alternative. Therefore, it is common for cloud modernisation to form part of an
on-premises modernisation approach.
The Infrastructure-as-a-Service (IaaS) cloud-based model is based on virtualisation
but differs from on-premises virtualisation in that the company has no control over
the physical host or the hypervisor on which their virtualised servers run. However,
they can still log in, install the software they require and patch it. Customers have a
choice to pay for their SQL Server licence on a pay-as-you-go basis where the SQL
Server license is incorporated into the cost of the virtual machine. Alternatively, those
with Software Assurance can exercise their License Mobility rights and use their
Enterprise Core licenses to license the virtual machines.
When using Azure SQL Database – Microsoft’s Platform-as-a-Service (PaaS) offering
– administrators only have access to the database itself and not the underlying
operating system and virtual machine. Typically, it’s cheaper to run than IaaS,
which requires more infrastructure setup and fully licenced versions of SQL Server.
We believe that Microsoft sees PaaS as the ultimate destination for its customers.
Microsoft offers three services within its Azure SQL Database family:
This option is particularly suitable for those looking to create and deploy new applications with short time to market constraints. There are two options for deploying a Single Database, the first being DTUs (a measure of performance that blends CPU, Memory, Data I/O and Log I/O). The workload will be throttled if it hits the service tier quota, and the application’s performance may start to suffer. The other option is to purchase based on vCores and Memory, under the vCore purchasing model. This enables storage and compute to be scaled independently whilst also allowing for more advanced purchasing methods. Our blog post “New vCore purchasing option for Azure SQL Database” explains these options in more detail.
Rather than having an individual database with a set amount of DTUs, or vCores, a company may decide to group numerous databases into a pool that share those resources. This is especially useful if the databases have different peaks and troughs in their usage. If they all peak at the same time they run the risk of being throttled as they will run out of the resources within the pool, so it may be more cost-effective to consider a Single Database in this case.
Microsoft’s newest offering; the customer has an instance of SQL Server they can deploy databases onto and a SQL Server Agent they can use to run scheduled jobs. It has been designed to simplify lift-and-shift migrations while still providing many of the benefits of PaaS. However, unlike a virtual machine, users don’t have access to the underlying operating system, but can make limited instance level configuration changes. Furthermore, Managed Instance is priced by vCores only, rather than DTUs. This option can be expensive and therefore tends to be more cost-effective for companies running large numbers of databases. You can find out more about Managed Instances and the features included on Coeo’s blog.
Find out more
Coeo offers an Azure Data Platform Jumpstart, which is designed to help kick off modernisation programmes.