Group commit timers and high volume transaction systems

Helland, Pat; Sammer, Harald; Lyon, Jim; Carr, Richard; Garrett, Phil; Reuter, Andreas

doi:10.1007/3-540-51085-0_52

Cited by 33 publications

(13 citation statements)

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“…For operations that may be buffered, such as clean and write-clean, an SSC uses asynchronous group commit [Helland et al 1988] to flush the log records from device memory to flash device periodically. For operations with immediate consistency guarantees, such as write-dirty and evict, the log is flushed as part of the operation using a synchronous commit.…”

Section: Persistencementioning

confidence: 99%

Design and Prototype of a Solid-State Cache

Saxena

Swift

2014

ACM Trans. Storage

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The availability of high-speed solid-state storage has introduced a new tier into the storage hierarchy. Lowlatency and high-IOPS solid-state drives (SSDs) cache data in front of high-capacity disks. However, most existing SSDs are designed to be a drop-in disk replacement, and hence are mismatched for use as a cache.This article describes FlashTier, a system architecture built upon a solid-state cache (SSC), which is a flash device with an interface designed for caching. Management software at the operating system block layer directs caching. The FlashTier design addresses three limitations of using traditional SSDs for caching. First, FlashTier provides a unified logical address space to reduce the cost of cache block management within both the OS and the SSD. Second, FlashTier provides a new SSC block interface to enable a warm cache with consistent data after a crash. Finally, FlashTier leverages cache behavior to silently evict data blocks during garbage collection to improve performance of the SSC.We first implement an SSC simulator and a cache manager in Linux to perform an in-depth evaluation and analysis of FlashTier's design techniques. Next, we develop a prototype of SSC on the OpenSSD Jasmine hardware platform to investigate the benefits and practicality of FlashTier design. Our prototyping experiences provide insights applicable to managing modern flash hardware, implementing other SSD prototypes and new OS storage stack interface extensions.Overall, we find that FlashTier improves cache performance by up to 168% over consumer-grade SSDs and up to 52% over high-end SSDs. It also improves flash lifetime for write-intensive workloads by up to 60% compared to SSD caches with a traditional flash interface. ACM Reference Format:Mohit Saxena and Michael M. Swift. 2014. Design and prototype of a solid-state cache.

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Section: Persistencementioning

confidence: 99%

Design and Prototype of a Solid-State Cache

Saxena

Swift

2014

ACM Trans. Storage

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“…Although both WAL and shadow paging have been implemented in real systems, shadow paging is not as popular as WAL for disk-based databases due to performance reasons [26], [32]. Over the past few decades, considerable research efforts have been devoted to the optimization of WAL performance, e.g., group commit [14], finer-grained logging [33], multi-core techniques [16], to name but a few. Alternatively, log-structured databases adopt log-only storage for alleviating write I/Os and supporting fast system recovery [36].…”

Section: Related Workmentioning

confidence: 99%

PCMLogging: Optimizing Transaction Logging and Recovery Performance with PCM

Gao

Härder

et al. 2015

IEEE Trans. Knowl. Data Eng.

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Phase-change memory (PCM), as one of the most promising next-generation memory technologies, offers various attractive properties such as non-volatility, byte addressability, bit alterability, and low idle energy consumption. Recently, PCM has drawn much attention from the database community for optimizing query and transaction performance. As a complement to existing work, we present PCMLogging, a novel logging scheme that exploits PCM for both data caching and transaction logging to minimize I/O accesses in disk-based databases. Specifically, PCMLogging caches dirty pages/records in PCM and further maintains an implicit log in the cached updates to support database recovery. By integrating log and cached updates, PCMLogging enables simplified recovery and prolongs PCM lifetime. Furthermore, using PCMLogging, we develop a wear-leveling algorithm, that evenly distributes the write traffic across the PCM storage space, and a cost-based destaging algorithm that adaptively migrates cached data from PCM to external storage. Compared to classical write-ahead logging (WAL), our trace-driven simulation results reveal up to 1∼20X improvement in system throughput.

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“…Further, log flush delays become serial if the log device is overloaded by multiple small requests. Fortunately, log flush I/O times become less important as fast solid-state drives gain popularity [1,19], and when using techniques such as group commit [12].…”

Section: I/o-related Delays (A)mentioning

confidence: 99%

“…Log group commit strategies [12,31] reduce the pressure on (magnetic-or flash-based) log disks by aggregating multiple requests for log flush into a single I/O operation; fewer and larger disk accesses translate into significantly better disk performance by avoiding unnecessary head seeks. Unfortunately, group commit does not eliminate unwanted context switches because transactions merely block pending notification from the log rather than blocking on I/O requests directly.…”

Section: Handling Logging-related Problemsmentioning

confidence: 99%

Scalability of write-ahead logging on multicore and multisocket hardware

et al. 2011

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The shift to multi-core and multi-socket hardware brings new challenges to database systems, as the software parallelism determines performance. Even though database systems traditionally accommodate simultaneous requests, a multitude of synchronization barriers serialize execution. Write-ahead logging is a fundamental, omnipresent component in ARIES-style concurrency and recovery, and one of the most important yet-to-be addressed potential bottlenecks, especially in OLTP workloads making frequent small changes to data. In this paper, we identify four loggingrelated impediments to database system scalability. Each issue challenges different level in the software architecture: (a) the high volume of small-sized I/O requests may saturate the disk, (b) transactions hold locks while waiting for the log flush, (c) extensive context switching overwhelms the OS scheduler with threads executing log I/Os, and (d) contention appears as transactions serialize accesses to in-memory log data structures. We demonstrate these problems and address them with techniques that, when combined, comprise a holistic, scalable approach to logging. Our solution achieves a 20-69% speedup over a modern database system when running log-intensive workloads, such as the TPC-B and TATP benchmarks, in a single-socket multiprocessor server. Moreover, it achieves log insert throughput over 2.2 GB/s for small log records on the single-socket server, roughly 20 times higher than the traditional way of accessing the log using a single mutex. Furthermore, we investigate techniques on scaling the performance of logging to multi-socket servers. We present a set of optimizations which partly ameliorate the latency penalty that comes with multi-socket hardware, and then we investigate the feasibility of applying a distributed log buffer design at the socket level.

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Group commit timers and high volume transaction systems

Cited by 33 publications

References 0 publications

Design and Prototype of a Solid-State Cache

Design and Prototype of a Solid-State Cache

PCMLogging: Optimizing Transaction Logging and Recovery Performance with PCM

Scalability of write-ahead logging on multicore and multisocket hardware

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