Performance analysis of NVMe SSDs and their implication on real world databases

The storage subsystem has undergone tremendous innova-tion in order to keep up with the ever-increasing demand for throughput. Non Volatile Memory Express (NVMe) based solid state devices are the latest development in this do-main, delivering unprecedented performance in terms of la-tency and peak bandwidth. NVMe drives are expected to be particularly beneficial for I/O intensive applications, with databases being one of the prominent use-cases. This paper provides the first, in-depth performance analy-sis of NVMe drives. Combining driver instrumentation with system monitoring tools, we present a breakdown of access times for I/O requests throughout the entire system. Fur-thermore, we present a detailed, quantitative analysis of all the factors contributing to the low-latency, high-throughput characteristics of NVMe drives, including the system soft-ware stack. Lastly, we characterize the performance of mul-tiple cloud databases (both relational and NoSQL) on state-of-the-art NVMe drives, and compare that to their perfor-mance on enterprise-class SATA-based SSDs. We show that NVMe-backed database applications deliver up to 8 × su-perior client-side performance over enterprise-class, SATA-based SSDs

Travel cost budget based user equilibrium in a bottleneck model with stochastic capacity

This paper studies a bottleneck model in which the capacity of the bottleneck is constant within a day but changes stochastically from day-to-day between a designed value (good condition) and a degraded one (bad condition). The study relates the travel cost variability due to stochastic capacity with commuters' departure time choice behaviors. We postulate that commuters acquire the variability of travel cost based on past experiences and factor such variability into their departure time choice consideration by minimizing their travel cost budget (TCB), defined as a weighted average of mean travel cost and standard deviation of travel cost. We show that the consideration of TCB yields seven possible equilibrium patterns. Closed form solutions to all possible equilibrium patterns and their corresponding parameter ranges are derived. The rationality of the patterns has been investigated. Dependence of travel cost and the duration of peak hours on the commuters' risk attitude has also been derived in each equilibrium pattern. Finally, numerical studies have been conducted to illustrate the properties

Rack level scheduling for containerized workloads

High performance SSDs have become ubiquitous in warehouse scale computing. Increased adoptions can be attributed to their high bandwidth, low latency and excellent random I/O performance. Owing to this high performance, multiple I/O intensive services can now be co-located on the same server. SSDs also introduce periodic latency spikes due to garbage collection. This, combined with multi-tenancy increases latency unpredictability since co-located applications now compete for CPU, memory, and disk bandwidth. The combination of these latency spikes and unpredictability lead to long tail latencies that can significantly decrease the system performance at scale. In this paper, we present a rack-level scheduling algorithm, which dynamically detects and shifts workloads with long tail latencies within servers in the same rack. Different from the global resource management methods, rack-level scheduling utilizes lightweight containers to minimize data movement and message passing overheads, leading to a much more efficient solution to reduce tail latency.With the algorithms implemented in the storage driver of the containerization infrastructure, it becomes viable to deploy and migrate applications in existing server racks without extensive modifications to storage, OS and other subsystems.by Qiumin Xu, Krishna T. Malladi and Manu Awasthi

Mechanisms of Action of Mesenchymal Stem Cells in Metabolic-Associated Fatty Liver Disease

Metabolic-associated fatty liver disease (MAFLD) is currently the most common chronic liver disease worldwide. However, its pathophysiological mechanism is complicated, and currently, it has no FDA-approved pharmacological therapies. In recent years, mesenchymal stem cell (MSC) therapy has attracted increasing attention in the treatment of hepatic diseases. MSCs are multipotent stromal cells that originated from mesoderm mesenchyme, which have self-renewal and multipotent differentiation capability. Recent experiments and studies have found that MSCs have the latent capacity to be used for MAFLD treatment. MSCs have the potential to differentiate into hepatocytes, which could be induced into hepatocyte-like cells (HLCs) with liver-specific morphology and function under appropriate conditions to promote liver tissue regeneration. They can also reduce liver tissue injury and reverse the development of MAFLD by regulating immune response, antifibrotic activities, and lipid metabolism. Moreover, several advantages are attributed to MSC-derived exosomes (MSC-exosomes), such as targeted delivery, reliable reparability, and poor immunogenicity. After entering the target cells, MSC-exosomes help regulate cell function and signal transduction; thus, it is expected to become an emerging treatment for MAFLD. In this review, we comprehensively discussed the roles of MSCs in MAFLD, main signaling pathways of MSCs that affect MAFLD, and mechanisms of MSC-exosomes on MAFLD

Performance analysis of containerized applications on local and remote storage

by Qiumin Xu, Manu Awasthi, Krishna T. Malladi, Janki Bhimani, Jingpei Yang and Murali Annavara

Preparation and characterization of Cr-doped tungsten oxide by liquid-liquid doping precursor

The tungsten oxides with uniformly grain growth inhibitor elements can significantly improve the distribution of inhibitors in the subsequent WC powders, and finally enhanced the properties of ultra-fine grained cemented carbides. Thus, a new liquid-liquid doping method was used to prepare the tungsten oxide composite powders with grain growth inhibitor elements by spray drying-calcining process. The microstructure and phase transition of Cr-doped and undoped tungsten oxide composite powders were studied by TG/DSC, XRD, SEM, and XPS. The results showed that Cr doping has little effect on the morphology of the precursor powders after spray drying. However, the existence of ammonium chromate had a significant effect on the properties of the calcined tungsten oxide. The volume expansion of ammonium chromate could reduce the decomposition temperature of ammonium tungstate precursor powders. Additionally, the formation of thermodynamic instability Cr-O-W compound could be the reason for the exothermic peak appeared at 486.3 °C. Moreover, the ‘liquid-liquid’ doping method guaranteed the uniform distribution of Cr _2 O _3 , which was favourable for the stable existence of hexagonal metastable h-WO _3 . The tungsten oxide powders calcined at 600 °C have a flaky morphology due to the uniform distribution of Cr _2 O _3 , and the uniform distribution of Cr _2 O _3 in the powder can also prevent the grain growth of WO _3

Docker container scheduler for I/O intensive applications running on NVMe SSDs

By using fast back-end storage, performance benefits of a lightweight container platform can be leveraged with quick I/O response. Nevertheless, the performance of simultaneously executing multiple instances of same or different applications may vary significantly with the number of containers. The performance may also vary with the nature of applications because different applications can exhibit different nature on SSDs in terms of I/O types (read/write), I/O access pattern (random/sequential), I/O size, etc. Therefore, this paper aims to investigate and analyze the performance characterization of both homogeneous and heterogeneous mixtures of I/O intensive containerized applications, operating with high performance NVMe SSDs and derive novel design guidelines for achieving an optimal and fair operation of the both homogeneous and heterogeneous mixtures. By leveraging these design guidelines, we further develop a new docker controller for scheduling workload containers of different types of applications. Our controller decides the optimal batches of simultaneously operating containers in order to minimize total execution time and maximize resource utilization. Meanwhile, our controller also strives to balance the throughput among all simultaneously running applications. We develop this new docker controller by solving an optimization problem using five different optimization solvers. We conduct our experiments in a platform of multiple docker containers operating on an array of three enterprise NVMe drives. We further evaluate our controller using different applications of diverse I/O behaviors and compare it with simultaneous operation of containers without the controller. Our evaluation results show that our new docker workload controller helps speed-up the overall execution of multiple applications on SSDs.Janki Bhimani,Zhengyu Yang,Ningfang Mi,Jingpei Yang,Jingpei Yang,Manu Awasthi, Rajinikanth Pandurangan,Vijay Balakrishna