Loading [MathJax]/extensions/MathMenu.js
Sang-Yun Jeon - IEEE Xplore Author Profile

Showing 1-25 of 188 results

Filter Results

Show

Results

Emerging persistent memory (PM) promises near-DRAM performance, larger capacity, and data persistence, attracting researchers to design PM-based key-value stores. However, existing PM-based key-value stores lack awareness of the Non-Uniform Memory Access (NUMA) architecture on PM, where accessing PM on remote NUMA sockets is considerably slower than accessing local PM. This NUMA-unawareness result...Show More
Emerging high-performance computing (HPC) applications with diverse workload characteristics impose greater demands on parallel file systems (PFSs). PFSs also require more efficient software designs to fully utilize the performance of modern hardware, such as multi-core CPUs, Remote Direct Memory Access (RDMA), and NVMe SSDs. However, existing PFSs expose great limitations under these requirements...Show More
Dynamic random access memory (DRAM) is being upgraded iteratively, and as a result, its transmission rate and bandwidth are rising quickly. Simultaneously, as the DRAM process has advanced, the storage cell size has decreased and cell integration has improved within each device, leading to a significant boost in storage capacity and density. DRAM has been widely utilized as a crucial storage compo...Show More
Although three-dimensional (3D) NAND flash memory has demonstrated impressive benefits including high capacity and storage density, data reliability is now a major worry because of long-term storage and ongoing cell wear-out. Low-density parity-check (LDPC) codes are frequently utilized in flash storage systems because of their superior error correcting capabilities to guarantee data reliability. ...Show More
NVMe zoned namespace (ZNS) SSDs present a new class of storage devices with attractive features including low cost, software definability, and stable performance. However, one primary culprit that hinders the adoption of ZNS is the high garbage collection (GC) overhead it brings to host software. The ZNS interface divides the logical address space into size-fixed zones that must be written sequent...Show More
Three-dimensional (3D) NAND flash memory has been frequently utilized in consumer electronics as a popular storage device. However, data reliability has become an important problem to be solved. Low-density parity-check (LDPC) codes with superior error correction capability are commonly used in 3D NAND flash memory to ensure data reliability. Unfortunately, high raw bit error rate (RBER) induced b...Show More
Background (BG) tasks are maintained indispensably in multiple layers of storage systems, from applications to flash-based SSDs. They launch a large amount of I/Os, causing significant interference with foreground (FG) I/O performance. Our key insight is that, to mitigate such interference, holistic scheduling of system-wide, multi-source BG I/Os is required and can only be realized at the underly...Show More
Big data applications, such as recommendation system and social network, often generate a huge number of fine-grained reads to the storage. Block-oriented storage devices upon the traditional storage system rely on the paging mechanism to migrate pages to the host DRAM, tending to suffer from these fine-grained read operations in terms of I/O traffic as well as performance. Motivated by this chall...Show More
Low read latency, long lifetime, and high storage density have all been demonstrated in phase-change memory (PCM), making it an attractive contender for main memory. However, due to resistance drift per cell caused by long-term storage, data reliability becomes a major challenge. Low-density parity-check (LDPC) codes with improved error correction capability can be used in PCM to reduce bit error ...Show More
QLC flash-based SSDs are gaining increasing attention and are expected to be widely used in read-intensive application scenarios, since they provide high density and low cost but suffer from poor write endurance and performance. QLC flash has four types of pages, between which read latency variation is as large as 1.6 to 4.8 times. This raises a critical concern for QLC SSDs to provide adequate an...Show More
Sharing a flash-based solid-state drive (SSD) among multiple tenants has become a common practice to improve storage utilization and cost efficiency. Meanwhile, how to allocate limited storage resources, especially the over-provisioning space (OPS) resources, among competitive tenants has emerged as a critical problem. The OPS refers to additional user-invisible storage space, whose size influence...Show More
Three-dimension (3D) NAND flash memory is the preferred storage component of solid-state drive (SSD) for its high ratio of capacity and cost. Optimizing the reliability of modern SSD needs to test and collect a large amount of real-world error data from 3D NAND flash memory. However, the test costs have surged dozens of times as its capacity increases. It's imperative to reduce the costs of testin...Show More
LSM-tree is widely used in key-value stores for big data storage, but it suffers from write amplification brought by frequent compaction operations. An effective solution for this problem is key-value separation, which decouples values from the LSM-tree and stores them in a separate value log. However, existing key-value separation schemes achieve poor range query performance, especially for small...Show More
Duplicate writes are prevalent in storage systems, originating from data duplication, journaling, and data relocations, etc. As flash-based solid state drives (SSDs) have been widely deployed, duplicate writes can significantly degrade their performance and lifetime. Prior studies have proposed innovative approaches that exploit the address remapping utility inside an SSD to eliminate duplicate wr...Show More
Multilevel cell (MLC) NAND flash memory uses the voltages of the memory cells to represent bits, but high voltages cause much more damage on the cells than low voltages. Free space in MLC can be leveraged to reduce the usage of the high voltages and thus extend the lifetime of MLC. However, limited by the conventional data representation rule that represents bits by the voltage of one single cell,...Show More
For NAND flash memory, designing a good low-density parity-check (LDPC) decoding algorithm could ensure data reliability. When the decoding algorithm is implemented in hardware, it is necessary to achieve an attractive tradeoff between implementation complexity and decoding performance. In this article, a novel low-bit-width decoding scheme is introduced. In this scheme, the quasi-cyclic LDPC (QC-...Show More
The RAID-10 architecture has been widely deployed in commercial and industrial storage environments over the past two decades due to its high reliability, availability, and performance. However, during the recovery process of a single disk failure, which accounts for more than 99.75% of the disk failure scenarios, it is still at a high risk of data loss and suffers from a degradation of user I/O p...Show More
Log-structured file systems (LS-FSs) sequentialize writes, so they are expected to perform well on flash-based SSDs. However, we observe a semantic gap between the LS- FS and SSD that causes a stale-LBA problem. When data are updated, the LS-FS allocates new logical block addresses (LBAs). The relevant stale LBAs are invalidated and then trimmed or reused with a delay by the LS-FS. During the time...Show More
To resolve the low generalization ability of the flash lifetime model caused by a small training sample, we propose a multiple source ensemble online domain adaptation scheme, called MSE. MSE uses multiple offline source blocks to assist in establishing a lifetime prediction model for the online target block. MSE migrates information from these blocks to the target block, effectively solving the p...Show More
Large-scale cloud storage systems use the logging mechanism to sequentially write data in an append-only manner. The write stream needs to be first appended and persisted into logging files, and then encoded with erasure coding (EC) in underlying storage. This introduces significant overhead to small write operations. To solve this problem, we propose EFLOG, a full-streaming storage framework that...Show More
The explosive growth of modern web-scale applications has made cost-effectiveness a primary design goal for their underlying databases. As a backbone of modern databases, LSM-tree based key-value stores (LSM store) face limited storage options. They are either designed for local storage that is relatively small, expensive, and fast or for cloud storage that offers larger capacities at reduced cost...Show More
Ubiquitous cameras continuously produce enormous surveillance videos, largely challenging the capacity of video analytics and storage system. Although such videos are encoded and compressed by codecs to effectively reduce inter-/intra-frame redundancy at pixel level, they still consume massive storage space, thus being deleted periodically to recycle storage. To reduce hardware pressure in both ef...Show More
3D NAND flash memory faces unprecedented complicated interference than planar NAND flash memory, resulting in more concern regarding reliability and performance. Stronger error correction code (ECC) and adaptive reading strategies are proposed to improve the reliability and performance taking a threshold voltage (Vth) distribution model as the backbone. However, the existing modeling methods are c...Show More
Write-ahead logging (WAL) has been widely used to provide transactional atomicity in databases, such as SQLite and MySQL/InnoDB. However, the WAL introduces duplicate writes, where changes are recorded in the WAL file and then written to the database file, called checkpointing writes. On the other hand, NAND flash-based SSDs, which have an inherent indirection software layer, called flash translat...Show More
Phase-change memory (PCM) as emerging non-volatile memory has attracted more attention and considered as the promising replacement of the main memory. PCM has shown good scalability and high storage density, but data storage reliability has become a challenge and concern. When data are written into PCM cells by a phase transition between amorphous and crystalline, the resistance of each state drif...Show More