With the rise of advanced workflow languages for scientific computations, Nextflow has gained increased attention from the bioinformatics community. Nextflow offers native support for advanced parallelism, which can greatly enhance resource utilization and throughput. Still, a significant portion of bioinformatics workflows are developed with the Common Workflow Language (CWL). Transitioning from CWL to Nextflow poses a significant challenge due to the differences in programming models, scripting language compatibilities, and the prerequisite for in-depth knowledge in both languages. To address this challenge, we present CNT, a novel, semi-automated translator converting CWL workflows into Nextflow ones. At its core, CNT uses an automated translation mechanism that converts the CommandLineTool, the most basic unit of CWL, into Nextflow's Process class. This component integrates tool-level conversion, graph dependency analysis, and correctness checks to provide highly automated translation coverage, significantly reducing the development time while satisfying language-specific requirements like building a proper dataflow model when creating workflows. Furthermore, CNT incorporates a module for aiding manual translation. Specifically, it can identify three common JavaScript patterns in CWL workflows, offering further guidance for developers during the translation phase. We evaluated CNT with production-grade workflows and found that it can cover up to 81% of the original workflows, substantially reducing development time. Additionally, transitioning from a cwltool-based system to Nextflow with CNT can result in a 72% speedup and 85% increased CPU utilization.

Predictable latency on flash storage is a long-pursuit goal, yet unpredictability stays due to the unavoidable disturbance from many well-known SSD internal activities. To combat this issue, the recent NVMe IO Determinism (IOD) interface advocates host-level controls to SSD internal management tasks. Although promising, challenges remain on how to exploit it for truly predictable performance. We present IODA , 1 an I/O deterministic flash array design built on top of small but powerful extensions to the IOD interface for easy deployment. IODA exploits data redundancy in the context of IOD for a strong latency predictability contract. In IODA , SSDs are expected to quickly fail an I/O on purpose to allow predictable I/Os through proactive data reconstruction. In the case of concurrent internal operations, IODA introduces busy remaining time exposure and predictable-latency-window formulation to guarantee predictable data reconstructions. Overall, IODA only adds five new fields to the NVMe interface and a small modification in the flash firmware while keeping most of the complexity in the host OS. Our evaluation shows that IODA improves the 95–99.99 th latencies by up to 75×. IODA is also the nearest to the ideal, no disturbance case compared to seven state-of-the-art preemption, suspension, GC coordination, partitioning, tiny-tail flash controller, prediction, and proactive approaches.

Predictable latency on flash storage is a long-pursuit goal, yet, unpredictability stays due to the unavoidable disturbance from many well-known SSD internal activities. To combat this issue, the recent NVMe IO Determinism (IOD) interface advocates host-level controls to SSD internal management tasks. While promising, challenges remain on how to exploit it for truly predictable performance.