An official website of the United States government
Storage systems are designed to never lose data. However, modern applications increasingly use local storage to improve performance by storing soft state such as cached, prefetched or precomputed results. Required is elastic storage, where cloud providers can alter the storage footprint of applications by removing and regenerating soft state based on resource availability and access patterns. We propose a new abstraction called a motif that enables storage elasticity by allowing applications to describe how soft state can be regenerated. Carillon is a system that uses motifs to dynamically change the storage space used by applications. Carillon is implemented as a runtime and a collection of shim layers that interpose between applications and specific storage APIs; we describe shims for a filesystem (Carillon-FS) and a key-value store (Carillon-KV). We show that Carillon-FS allows us to dynamically alter the storage footprint of a VM, while Carillon-KV enables a graph database that accelerates performance based on available storage space
more »
« less
The Storage Hierarchy is Not a Hierarchy: Optimizing Caching on Modern Storage Devices with Orthus
We introduce non-hierarchical caching (NHC), a novel approach to caching in modern storage hierarchies. NHC improves performance as compared to classic caching by redirecting excess load to devices lower in the hierarchy when it is advantageous to do so. NHC dynamically adjusts allocation and access decisions, thus maximizing performance (e.g., high throughput, low 99%-ile latency). We implement NHC in Orthus-CAS (a block-layer caching kernel module) and Orthus-KV (a user-level caching layer for a key-value store). We show the efficacy of NHC via a thorough empirical study: Orthus-KV and Orthus-CAS offer significantly better performance (by up to 2x) than classic caching on various modern hierarchies, under a range of realistic workloads.
more »
« less
- Award ID(s):
- 1838733
- PAR ID:
- 10299720
- Date Published:
- Journal Name:
- USENIX FAST
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
null (Ed.)Key-value store based on a log-structured merge-tree (LSMtree) is preferable to hash-based KV store because an LSMtree can support a wider variety of operations and show better performance, especially for writes. However, LSM-tree is difficult to implement in the resource constrained environment of a key-value SSD (KV-SSD) and consequently, KV-SSDs typically use hash-based schemes. We present PinK, a design and implementation of an LSM-tree-based KV-SSD, which compared to a hash-based KV-SSD, reduces 99th percentile tail latency by 73%, improves average read latency by 42% nd shows 37% higher throughput. The key idea in improving the performance of an LSM-tree in a resource constrained environment is to avoid the use of Bloom filters and instead, use a small amount of DRAM to keep/pin the top levels of the LSM-tree.more » « less
-
Many modern key-value stores, such as RocksDB, rely on log-structured merge trees (LSMs). Originally designed for spinning disks, LSMs optimize for write performance by only making sequential writes. But this optimization comes at the cost of reads: LSMs must rely on expensive compaction jobs and Bloom filters---all to maintain reasonable read performance. For NVMe SSDs, we argue that trading off read performance for write performance is no longer always needed. With enough parallelism, NVMe SSDs have comparable random and sequential access performance. This change makes update-in-place designs, which traditionally provide excellent read performance, a viable alternative to LSMs. In this paper, we close the gap between log-structured and update-in-place designs on modern SSDs with the help of new components that take advantage of data and workload patterns. Specifically, we explore three key ideas: (A) record caching for efficient point operations, (B) page grouping for high-performance range scans, and (C) insert forecasting to reduce the reorganization costs of accommodating new records. We evaluate these ideas by implementing them in a prototype update-in-place key-value store called TreeLine. On YCSB, we find that TreeLine outperforms RocksDB and LeanStore by 2.20× and 2.07× respectively on average across the point workloads, and by up to 10.95× and 7.52× overall.more » « less
-
null (Ed.)Abstract This review introduces relevant nanoscale thermal transport processes that impact thermal abatement in power electronics applications. Specifically, we highlight the importance of nanoscale thermal transport mechanisms at each layer in material hierarchies that make up modern electronic devices. This includes those mechanisms that impact thermal transport through: (1) substrates, (2) interfaces and 2-D materials and (3) heat spreading materials. For each material layer, we provide examples of recent works that (1) demonstrate improvements in thermal performance and/or (2) improve our understanding of the relevance of nanoscale thermal transport across material junctions. We end our discussion by highlighting several additional applications that have benefited from a consideration of nanoscale thermal transport phenomena, including RF electronics and neuromorphic computing.more » « less
-
Traditional caching models emphasize hit rate as the principal measure of performance for cache replacement algorithms. However, hit rate alone can be misleading in the presence of a phenomenon known as a delayed hit. Delayed hits occur in high-throughput systems when multiple requests for an object accumulate before the object can be fetched from the backing store. Prior work by Atre et al. has explored the impact of delayed hits in simple caching scenarios, namely single-tier caches with uniform object sizes. In this work we seek to extend that investigation to consider multi-level caches, such as those that might be found in a modern CDN. Furthermore, we extend MAD, the delayed-hits-aware policy proposed by Atre et al, so that it can be deployed in a multi-tier caching system. We evaluate the performance of MAD using a multi-tier cache simulator and an empirical cache configuration based on modern CDNs. Our initial results lead us to believe that delayed hits can still be a prominent factor in the performance of multi-level caches, although their effect may be reduced in comparison to simpler cache configurations.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Conference Paper:
- The DOI is not currently available.
