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Storage is one of the biggest capital expenditures in the data center. Enterprises are creating and retaining increasing amounts of data, hoping to exploit some potential future value. One scenario to manage costs is to use storage as a service. What does this mean and how can SaaS be part of an enterprise's overall data management strategy?
IT organizations are already familiar with as-a-service offerings, such as software as a service and infrastructure as a service. The common theme with these offerings is the way in which the technology is acquired. The customer doesn't own the technology used to deliver these services but instead is charged for their use. In the case of storage as a service (SaaS), this typically means a charge per gigabyte or terabyte per month, based on a tier of performance.
The three types of SaaS are public cloud, private cloud and colocation, defined as follows:
1. Public cloud
The public cloud offers SaaS as a shared infrastructure. Public cloud SaaS has been available since AWS introduced S3 in 2006. The object store charges per gigabyte of data stored, with variations in price for reduced availability and performance. Public cloud service providers also have block and file offerings, although block storage is typically restricted to access via cloud compute instances.
As a model of how storage services can be delivered, public cloud storage can deliver limitless capacity, can scale up and down and requires little or no commitment in terms of capacity or term of use.
2. Private cloud
Private storage-as-a-service offerings are more complex to deliver. Where public cloud storage is shared infrastructure, private SaaS is dedicated to a single customer. This represents a challenge for the service provider, which must balance ensuring capacity exists onsite to meet demand with not creating stranded resources that go unused and push up costs.
On-premises SaaS vendors typically require a minimum capacity commitment, such as 100 TB, and a minimum term, which is usually a year of use. However, some vendors are looking to deliver lower capacities with terms as short as one month.
A third option is to use a colocation service, where the vendor installs the infrastructure close to a public cloud provider or a local network point of presence. The customer consumes storage resources over the network, with the benefit of both low latency and access to shared resources. This approach delivers a service closely aligned to the private cloud model, with the option to use either dedicated or shared equipment and access platform-specific features like snapshots and data replication. The customer is expected to cover networking costs to access the storage.
All SaaS offerings come with service-level objectives (SLOs) as part of a contractual service-level agreement (SLA). In the public cloud, typical SLOs are lower than the enterprise, where five or six 9's of availability is the accepted norm. Missing an SLO generally results in the vendor offering service credits, rather than any financial payment. Businesses may have to build more resilience into their application designs to deliver higher levels of availability when using cloud storage.
Customers using SaaS offerings delivered in the public cloud can expect to see new services implemented as a continual process, based on the service provider's timeline. The customer has little or no input into planned outages or upgrades.
Service management can be more complex with on-premises SaaS. The customer has more influence over timing for software patching and upgrades because the hardware is exclusive. However, the SLA on problem diagnosis and fault resolution, such as for failed components, should be examined carefully to ensure it doesn't result in any business risk. Turnaround times may not be the same as those with leased or purchased storage.
Data protection is on you
SaaS isn't typically offered with data protection. In the case of public cloud, the cloud service provider will restore a failed service to the point of outage. However, there have been instances where cloud service providers have failed to recover data after a hardware failure. Data protection sits squarely with the customer in all SaaS instances and should be considered an additional cost.
Upgrades vary with service type
Enterprises typically have storage refresh cycles that replace technology every three or four years. Higher maintenance costs, once the initial term has passed, are usually the driving force behind this. A refresh is also often financially attractive because it can result in power, space and cooling savings.
With public cloud and colocated services, technology refresh is obfuscated from the customer. Over time, providers refresh their services, offering newer, faster and cheaper services. Customers can choose to take advantage and migrate to the new services -- or not.
In SaaS delivered on premises, technology refresh occurs as part of a perpetual or evergreen deployment model. The service provider will maintain storage capacity in place as long as the service contract exists. Technology refresh is determined by the SLA. Some vendors have products that can deliver in-place non-disruptive upgrades, whereas others may need to replace hardware through a migration project.
SaaS on the balance
Storage as a service can be a great approach for managing costs, as it avoids upfront capital outlays and aligns costs to consumption. However, the vendor retains control and ownership of the equipment. This may be challenging for enterprises that are used to having full platform access and control, but it can be a small price to pay for the operational and financial benefits.