I N V E N T I V E. SSD Firmware Complexities and Benefits from NVMe. Steven Shrader

Transcription

1 I N V E N T I V E SSD Firmware Complexities and Benefits from NVMe Steven Shrader

2 Agenda Introduction NVMe architectural issues from NVMe functions Structures to model the problem Methods (metadata attributes) to make the structure work well Attributes for a full system design Conclusion 2

3 Introduction NVMe is the solution to the interface performance bottleneck for high performance SSD s. NVMe through PCIe allows performance scalability in latency and bandwidth. (1M IOPS) Adds new functionality for virtualization and power control. 3

4 NVMe architectural issues from NVMe functions

5 Aspects of NVMe functions Write Read Many virtual drives through one interface Consume less power What is your health Status Configuration 5

6 NVMe architectural issues from NVMe functions Host Memory NVMe transport SQ list NVMe IO transaction (Virtual controller) PCIe host PCIe device CQ list Hardware/software Virtualization for many controllers 6

7 Structures to model the problem

8 Structures to model the problem 1 Limit the total number of queues and entries in the queue by the requirements of the host system. Limit the total complexity of the interface by specifying the max number of parallel commands. Host memory 20,000 Commands ready Memory Subsystem 1,000 Commands in Progress Storage array 1 Storage array 2 Storage array 3 Storage array 4 Storage array 5 Storage array 6 8

9 Structures to model the problem 2 Allow the controller to transfer the command data in managed units in random order to take advantage of cache or retrieval order from flash memory. Need the ability to time schedule buffer and or buss usage to achieve max throughput. Host memory 1 Command size 6 Memory Subsystem 1 Command split ordered 5 2 Storage array 1 Storage array 2 PRP Order LBA Order Storage array 3 Storage array 4 Storage array 5 3 Storage array 6 9

10 Trim Trim Trim LBA storage LBA storage LBA storage LBA storage Flash page unmapped remapped remapped unmapped remapped remapped remapped 10

11 Methods (metadata attributes) to make the structure work well

12 Methods (metadata attributes) to make the structure work well 1 I D X Flash Page ECC block ECC block ECC block ECC block I I I D D D X X X User Data Block User Data Block User Data Block User HDR HDR HDR Data Block Page info ECC Flash Page Next ECC block I D X User Data Block Continuation of block between flash pages 12

13 Methods (metadata attributes) to make the structure work well 2 I D X Flash Page ECC block ECC block ECC block ECC block I I I D D D X X X User Data Block User Data Block User Data Block User HDR HDR HDR Data Block Page info ECC FTL Entry A size 1 FTL Entry B size 3 FTL Entry C size 2 13

14 Methods (metadata attributes) to make the structure work well 3 Command expansion is the process of relating LBA s to physical storage. This is done in Atomic write units for each command. Host memory 1 Command size 6 Memory Subsystem 1 Command split ordered 5 2 Storage array 1 Storage array 2 PRP Order LBA Order Storage array 3 Storage array 4 Storage array 5 3 Storage array 6 14

15 Methods (metadata attributes) to make the structure work well 4 Namespaces can be any block of storage composed of a type of memory. Most generally, drive composed of a single storage medium, this will be another layer of mapping in front of the physical memory. Either as a set of blocks or as a linear list of physical blocks LBA storage NS 1 NS 2 NS 3 NS 4 NS 5 NS 6 NS N NS 1 NS 2 NS 3 LBA storage NSB 1 NSB 2 NSB 3 NSB 4 NSB 5 NSB 6 NSB N 15

16 Attributes for a full system design

17 Attributes for a full system design 1 Full system must include methods that work well from a system perspective Use full bandwidth of the PCIe by structuring the hardware to do data transfer to and from the host at the same time in a pipeline method For enterprise, a consistent performance for read/write from a host perspective is a big desire, therefore we need background processing to execute in it own timing to not interfere with host transactions read/writes Best if all storage can handle any attribute of a namespace Best if you can structure storage into as many namespaces as possible 17

18 Attributes for a full system design 2 Best if you can respond to low power requests from host system to achieve the best performance on the available power Include methods to analyze and understand the performance, power, errors, functions, actions of an implementation at speed 18

19 Conclusion

20 Conclusion We need to structure all hardware/software/interfaces to allow for all attributes in this presentation We need to combine high performance with configurability to achieve the highest performance based upon the available resources for a specific implementation Debug and analyze all components of the system cadence your complete NVMe solution 20

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