Research firm Gartner lists the public cloud as one of the fastest growing verticals in enterprise IT, and Amazon has apparently been taking notes. Some of Amazon Web Service’s (AWS) larger customers report that the cloud services provider is offering increasingly attractive deals with much more competitive pricing. What’s the catch? Vendor lock-in. The new deals have much less flexible terms than AWS’ traditional plans.

In one model, Amazon is offering deals that allow enterprises to exchange the pay-as-you-go model for a fixed monthly rate based on anticipated use. Customers don’t  pay more if they exceed the fixed amount, but they also don’t get a refund if they use less . Although there is some risk of paying for unused services, this model may be very attractive to organizations with fixed annual budgets.

Amazon is also offering reserved instances with reduced hourly rates for organizations willing to make a onetime payment upfront. Amazon claims reserved instances are up to 71 percent cheaper than normal instances. The plan is likely appeal to long term users, but for users that are unsure if they want to stay with AWS are likely to find it is not in their best interest to switch providers after they sign on the dotted line for a reserved instance .

In addition to the new pricing plans, AWS has also added a new EBS volume type. The new Provisioned IOPS (input/output operations per second) are designed to deliver predictable, high performance for I/O intensive workloads that need consistent and fast response times. The volumes allows customers to specify both volume size and performance, and AWS ensures the performance is delivered over the lifetime of the volume.

Users can increase performance to as much as 1,000 IOPS per volume. This cap will increase in the future according to the official blog post. Users can also combine volumes to realize even greater performance. There are also EBS-optimized instances available with dedicated throughout. AWS is the leader of the public cloud, but it’s not the only player. Vendors like Dell are hoping to grab a share of the market. Amazon will have to continue to innovate to keep existing customers and entice new ones, especially in the enterprise space.