Given ever-increasing data volumes, the cost of data storage is a critical concern. While solid state drives (SSDs) offer numerous performance benefits over hard drives, the cost per gigabyte (GB) of flash memory is still considered high compared to traditional data storage alternatives. LSI® SandForce® DuraWrite™ Virtual Capacity (DVC) is a unique feature of LSI SandForce flash controllers that extends the available storage space beyond the stated capacity of the underlying flash memory, helping to lower the cost per gigabyte of flash storage.


LSI SandForce Solution = More GB/$

DVC is a unique data reduction technology, which takes advantage of space normally used as additional over provisioning in an SSD. DVC returns a portion of this extra capacity to the user as additional storage space. DVC results in an increased storage capacity for the same physical flash memory, thereby reducing the cost per GB of delivered capacity to the user. With typical database applications, internal LSI testing has shown that DVC can be used to more than triple the capacity for storing user data.

DVC-Oracle Diagram
Source: Projection based on LSI internal testing of Oracle database entropy in LSI white paper, “Using DuraWrite™ Technology to Accelerate Flash Performance”, 2012.


Free Space Monitoring

The total increased capacity provided by DVC will vary based on the compressibility of the data itself. Traditional operating systems do not comprehend storage devices that change capacity over time. For this reason, DVC provides a dedicated SMART attribute to enable applications to control and monitor the remaining free physical space and manage the amount of valid data to ensure proper performance and behavior. For customers who can modify or create their own storage operating system, this monitoring and control capability can be completely automated.



DVC offers greater advantages in applications with lower entropy data workloads, such as the boot drives and caching drives found in many hyperscale datacenter and cloud computing servers. Applications with higher entropy data workloads still benefit from this technology, but the capacity increase will not be as high.


Specifications and Availability

  • Virtual capacity reporting via IDENTIFY DEVICE
  • Free space monitoring via SMART attribute
  • Available with LSI® SandForce SF-2000 flash controllers configured with up to 256GB of raw flash memory