Solving Software-Defined Flash
for the Data Center
At Radian we’ve taken a system-driven approach to redefining software for Flash storage. Our Symphonic software
replaces the SSD Flash-Translation-Layer (FTL) to overcome performance, cost, and endurance
limitations while providing the functionality required of a data center class product.
Matching Symphonic’s latency QoS and IOPS
takes more than 5x the leading FTL SSDs
1 Million IOPS at deterministic QoS
Symphonic based solution requires:
- Three 2TB SSDs
- 6TB raw Flash
- 5.8TB Addressable Capacity
Leading FTL based solution requires:
- Seventeen 2TB SSDs
- 34TB raw Flash
- 27TB Addressable Capacity
Symphonic compared to the leading FTL SSDs
- Performance – >80% increase in IOPS & User Bandwidth
By operating in host address space, Symphonic enables greater system parallelization, optimized data layout, and avoids duplicate table look ups and locking penalties.
- QoS – Magnitude improvement in latency determinism
Providing geometric alignment from the host down to the ‘bare metal’ avoids collisions which are the primary source of unpredictable latency spikes. Combined with performing garbage collection under intelligent host control, Symphonic provides a magnitude improvement in latency QoS that cannot be achieved with FTL architectures.
- Scalability – Metrics scale linearly with additional SSDs
Symphonic turns the SSD into an offload accelerator engine, freeing host resources while enabling linear scalability of IOPS/bandwidth, latency/QoS, and CPU/I-O as SSDs are added to a system.
- Cost Savings – Raw Flash reduced 15% or more
Symphonic does not require additional overprovisioning of raw Flash capacity for processes such as garbage collection. This results in reducing overprovisioning requirements from the 10% to 30% common in enterprise FTL SSDs down to less than 3%, in addition to reducing system-level overprovisioning.
- Endurance (TCO) – Write Amplification factor reduced 75%
By operating in host address space and performing Flash management processes under cooperative host control, Symphonic avoids the additional level of device write amplification induced by FTL SSDs to dramatically increase the usable life of the Flash media.
the answer to the SSD Delta
Why can’t conventional SSDs deliver the capacity, performance,
or endurance of their own raw Flash?
FTLs and the SSD Delta
Utilizing NAND memory for data storage requires performing Flash management processes, such as garbage collection and wear leveling.
SSDs perform these processes transparently in a black box known as the Flash-Translation-Layer (FTL) that abstracts the processes and emulates hard drives for backwards compatibility. But this abstraction significantly reduces the native performance and cost metrics available from the raw NAND memory, creating a gap that we call the SSD Delta.
Software-Defined Flash (SDF) removes the FTL, enabling the host software stack to directly perform Flash management processes and realize the full potential of the raw NAND memory. But in removing the FTL, other forms of SDF also create a new set of technical challenges.
Challenges from SDF
- Difficult integration and significant modifications to target host software stacks
- Burdens host with low level NAND details
- Lacks Forward Compatibility and ties host software to geometry and vendor-specific NAND properties
- Lacks Reliability, Availability, and Serviceability features
- Poor scalability as SSDs are added to a system
As a subset of SDF, Radian’s Symphonic technology preserves the SDF advantages while specifically addressing each of the resulting challenges to provide the functionality required of a data center class product.