NDLI: LightTx: A lightweight transactional design in flash-based SSDs to support flexible transactions

Content Provider	IEEE Xplore Digital Library
Author	Youyou Lu Jiwu Shu Jia Guo Shuai Li Mutlu, O.
Copyright Year	2013
Description	Author affiliation: Comput. Archit. Lab., Carnegie Mellon Univ., Pittsburgh, PA, USA (Mutlu, O.) \|\| Dept. of Comput. Sci. & Technol., Tsinghua Univ., Beijing, China (Youyou Lu; Jiwu Shu; Jia Guo; Shuai Li)
Abstract	Flash memory has accelerated the architectural evolution of storage systems with its unique characteristics compared to magnetic disks. The no-overwrite property of flash memory has been leveraged to efficiently support transactions, a commonly used mechanism in systems to provide consistency. However, existing transaction designs embedded in flash-based Solid State Drives (SSDs) have limited support for transaction flexibility, i.e., support for different isolation levels between transactions, which is essential to enable different systems to make tradeoffs between performance and consistency. Since they provide support for only strict isolation between transactions, existing designs lead to a reduced number of on-the-fly requests and therefore cannot exploit the abundant internal parallelism of an SSD. There are two design challenges that need to be overcome to support flexible transactions: (1) enabling a transaction commit protocol that supports parallel execution of transactions; and (2) efficiently tracking the state of transactions that have pages scattered over different locations due to parallel allocation of pages. In this paper, we propose LightTx to address these two challenges. LightTx supports transaction flexibility using a lightweight embedded transaction design. The design of LightTx is based on two key techniques. First, LightTx uses a commit protocol that determines the transaction state solely inside each transaction (as opposed to having dependencies between transactions that complicate state tracking) in order to support parallel transaction execution. Second, LightTx periodically retires the dead transactions to reduce transaction state tracking cost. Experiments show that LightTx provides up to 20.6% performance improvement due to transaction flexibility. LightTx also achieves nearly the lowest overhead in garbage collection and mapping persistence compared to existing embedded transaction designs.
Starting Page	115
Ending Page	122
File Size	322106
Page Count	8
File Format	PDF
ISBN	9781479929870
DOI	10.1109/ICCD.2013.6657033
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2013-10-06
Publisher Place	USA
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Ash Protocols Parallel processing Educational institutions Resource management Checkpointing Laboratories durability solid state drive flash memory transaction support atomicity
Content Type	Text
Resource Type	Article

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