Efficient Storage of Data Chunks in Solid State Drives

The data update mechanism for an SSD involves overprovisioning, e.g., a storage footprint larger than the actual data size, and write amplification, e.g., a physical amount of information written being a multiple of the actual amount of information. Both these overheads are exacerbated when applications randomly generate data chunks of size that is small compared to the size of the designed erase unit of the SSD. Per the techniques of this disclosure, small, random data chunks of similar size are padded such that a sequence of such data chunks aligns to the erase unit boundary of the SSD. At the same write amplification, overprovisioning is thereby reduced

Storing non-overlapped data streams in solid-state drives

In solid-state drives (SSDs), data is generally not updated in place. Rather, data update in SSDs involves garbage collection, in turn facilitated by over-provisioning of storage capacity. Over-provisioning reduces actual available storage capacity. Garbage collection results in write amplification, an undesirable phenomenon where the amount of information physically written is a multiple of the logical amount of information to be written. Write amplification reduces the life of the SSD. Write amplification is partially a result of treating input data streams as random data streams and subjecting the streams to a pre-configured maximum data capacity. Per the techniques described herein, input data streams, which may comprise sequential streams and/or random streams, are treated as non-overlapped data streams, e.g., streams that have non-overlapping logical addresses. The techniques thereby achieve near-zero over-provisioning with a close-to-unity write amplification and can provide SSD life and throughput that is significantly better than conventional techniques

Classifying SSD input-output streams to optimize storage overprovisioning

The data update mechanism for a solid-state drive (SSD) involves overprovisioning, e.g., a storage footprint larger than the actual data size, and write amplification, e.g., a physical amount of information written being a multiple of the actual amount of information. Both overprovisioning and write amplification overheads are at least partially a result of treating input data streams as statistically indistinguishable streams and subjecting them to fixed, pre-configured provisioning. This disclosure describes techniques to classify the input-output streams of an SSD into various types, e.g., non-overlapped sequential data, chunked data streams of variable length, etc. Overprovisioning is optimized for each input stream based on its classification. The techniques thereby reduce both overprovisioning and write amplification overheads, resulting in SSD life and throughput that is significantly better than conventional techniques

Adaptive Data-Coldness Classification For Solid State Drives

In solid-state drives (SSDs), data is not generally updated in place. Rather, data update in SSDs involves garbage collection, in turn facilitated by overprovisioning of storage capacity. Overprovisioning reduces actual available storage capacity. Garbage collection results in write amplification, an undesirable phenomenon where the amount of information physically written is a multiple of the logical amount of information to be written. Write amplification reduces the throughput and the life of the SSD. This disclosure describes techniques to adaptively classify data based on its coldness, e.g., recency and frequency of access, and dynamically allocate overprovisioning rates for each coldness category to achieve optimal write amplification and throughput

SimpleSSD: Modeling Solid State Drives for Holistic System Simulation

Existing solid state drive (SSD) simulators unfortunately lack hardware and/or software architecture models. Consequently, they are far from capturing the critical features of contemporary SSD devices. More importantly, while the performance of modern systems that adopt SSDs can vary based on their numerous internal design parameters and storage-level configurations, a full system simulation with traditional SSD models often requires unreasonably long runtimes and excessive computational resources. In this work, we propose SimpleSSD, a highfidelity simulator that models all detailed characteristics of hardware and software, while simplifying the nondescript features of storage internals. In contrast to existing SSD simulators, SimpleSSD can easily be integrated into publicly-available full system simulators. In addition, it can accommodate a complete storage stack and evaluate the performance of SSDs along with diverse memory technologies and microarchitectures. Thus, it facilitates simulations that explore the full design space at different levels of system abstraction.Comment: This paper has been accepted at IEEE Computer Architecture Letters (CAL

Evaluation of dermoscopic findings of longitudinal melanonychia in referred patients to dermatology clinics in Guilan, Iran

Introduction: Longitudinal melanonychia (LM) is a common clinical condition that is mostly identified by the presence of longitudinal, demarcated, and pigmented bands on the nail. Different benign or malignant pathologies can present with longitudinal melanonychia. Therefore, we aimed to investigate the frequency of dermoscopic features of LM in patients with LM referred to dermatology clinics in Guilan, Iran. Materials and Methods: This case-series study was conducted on 30 patients with LM who were referred to Besat clinic and Razi hospital, Rasht, Iran, from March 2022 to August 2022 with a complaint of LM. Demographical data and dermoscopic findings of patients were collected and analyzed using SPSS version 21. The LM and dermoscopic features were investigated using a dermatoscope (HEINE IC1, HEINE Optotechnik, Germany). Results: Out of 30 patients, 24 patients were female and 6 patients were male with a mean age of 30.08 ± 14.31 years old. Among these patients, five patients had a family history of LM, one patient with melanoma had Hutchinson’s sign, and three patients had pseudo-Hutchinson’s sign. The mean width of lesions of the nail was 2.42±2.12 mm with a mean time of onset of 7.42 ± 7.12 months. Also, the majority of the involved site of LM was hand (26.6%). Conclusion: According to our study, LM was more frequent in females and the trauma-related lesions of the nail were the most common dermatological findings among the patients