Chapter 2. System overview 15
Allocated storage is identified as storage that is allocated to a specific host (and unusable to 
other hosts), whether data is written. For thin-provisioning, the data that is written is 
considered used. For thick provisioning, total allocated volume space is considered used. 
IBM Storage Utility Offerings include the IBM FlashSystem 900 (9843-UF3), IBM Storwize 
V5030 (2078-U5A), and Storwize V7000 (2076-U7A) storage utility models that enable 
variable capacity usage and billing.
These models provide a fixed total capacity, with a base and variable usage subscription of 
that total capacity. IBM Spectrum Control Storage Insights is used to monitor the system 
capacity usage. It is used to report on capacity that is used beyond the base subscription 
capacity, which is referred to as variable usage. The variable capacity usage is billed on a 
quarterly basis. This feature enables customers to grow or shrink their usage, and pay for 
configured capacity only.
IBM Storage Utility Offering models are provided for customers who can benefit from a 
variable capacity system, where billing is based on provisioned space above the base. The 
base subscription is covered by a three-year lease that entitles the customer to use the base 
capacity at no additional cost. If storage needs increase beyond the base capacity, usage is 
billed based on the average daily provisioned capacity per terabyte, per month, on a quarterly 
basis.
Example
A customer has a Storwize V5030 utility model with 2 TB nearline disks, for a total system 
capacity of 48 TB. The base subscription for such a system is 16.8 TB. During the months 
where the average daily usage is below 16.8 TB, there is no additional billing.
The system monitors daily provisioned capacity and averages those daily usage rates over 
the month term. The result is the average daily usage for the month.
If a customer uses 25 TB, 42.6 TB, and 22.2 TB in three consecutive months, Storage 
Insights calculates the overage (rounding to the nearest terabyte), as listed in Table 2-2.
Table 2-2   Overage calculation
The capacity that is billed at the end of the quarter is a total of 39 TB-months in this example.
The usage data that is collected by Storage Insights is used by IBM to determine the physical 
data that is provisioned in the system. This data is compared to the base system capacity 
subscription, and any provisioned capacity beyond that base subscription is billed per 
terabyte, per month, on a quarterly basis. The calculated usage is based on the average use 
over a specific month. 
In a highly variable environment, such as managed or cloud service providers, this feature 
enables the system to be used only as much as is necessary during each month. Usage 
might increase or decrease, and is billed accordingly. Provisioned capacity is considered 
capacity that is reserved by the system. 
Average daily Base Overage To be billed
25 16.8 8.2 8
42.6 16.8 25.8 26
22.2 16.8 5.4 5