灵活数据放置对软件开发环境的影响.pdf

1、 2025 KIOXIA America,Inc.All Rights Reserved.Flexible Data PlacementLow Hanging Fruit:Results From a Real WorkloadSeptember 2025 2025 KIOXIA America,Inc.All Rights Reserved.2How Flash-Based Solid State Drives WorkMost Solid-State Drives(SSDs)utilize flash media.Flash Media has differing granularitie

2、s for read,program,and erase functionalities Erase occurs at the block level,which may be 10s of Mega Bytes(MB)in size Program occurs at the page level,which is typically 16 Kilo Bytes(KB)Read occurs at the sector size,which may be 4 KB Flash blocks can only perform one operation at a time(read,prog

3、ram,or erase)For performance reasons,most SSDs group many blocks striped across several die into“superblocks”Superblocks may be over 10 Giga Bytes(GB)in size When superblocks are used,they become the effective erase granularityContinued 2025 KIOXIA America,Inc.All Rights Reserved.3How Flash-Based So

4、lid State Drives Work(continued)Flash-based SSDs cannot overwrite in place due to these media restrictions New data associated with a Logical Block Address(LBA)is always written to a new page Old data associated with an LBA is marked as invalid Periodically the SSD performs a“Garbage Collect”(GC)ope

5、ration to copy valid data from a flash block that contains some invalid data so the entire block may be erased and reused.In extreme cases,a single 4 KB write may result in a SSD copying gigabytes of data internally The ratio of the amount of data written by the host to the amount of data written by

6、 the drive to the media is known as the Write Amplification Factor(WAF)2025 KIOXIA America,Inc.All Rights Reserved.4Flexible Data Placement:BackgroundFlexible Data Placement(FDP)was created to allow applications to group data within physical FLASH blocks.Ideally data would be organized such that ent