72,663 research outputs found
Elevating commodity storage with the SALSA host translation layer
To satisfy increasing storage demands in both capacity and performance,
industry has turned to multiple storage technologies, including Flash SSDs and
SMR disks. These devices employ a translation layer that conceals the
idiosyncrasies of their mediums and enables random access. Device translation
layers are, however, inherently constrained: resources on the drive are scarce,
they cannot be adapted to application requirements, and lack visibility across
multiple devices. As a result, performance and durability of many storage
devices is severely degraded.
In this paper, we present SALSA: a translation layer that executes on the
host and allows unmodified applications to better utilize commodity storage.
SALSA supports a wide range of single- and multi-device optimizations and,
because is implemented in software, can adapt to specific workloads. We
describe SALSA's design, and demonstrate its significant benefits using
microbenchmarks and case studies based on three applications: MySQL, the Swift
object store, and a video server.Comment: Presented at 2018 IEEE 26th International Symposium on Modeling,
Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS
Leveraging OpenStack and Ceph for a Controlled-Access Data Cloud
While traditional HPC has and continues to satisfy most workflows, a new
generation of researchers has emerged looking for sophisticated, scalable,
on-demand, and self-service control of compute infrastructure in a cloud-like
environment. Many also seek safe harbors to operate on or store sensitive
and/or controlled-access data in a high capacity environment.
To cater to these modern users, the Minnesota Supercomputing Institute
designed and deployed Stratus, a locally-hosted cloud environment powered by
the OpenStack platform, and backed by Ceph storage. The subscription-based
service complements existing HPC systems by satisfying the following unmet
needs of our users: a) on-demand availability of compute resources, b)
long-running jobs (i.e., days), c) container-based computing with
Docker, and d) adequate security controls to comply with controlled-access data
requirements.
This document provides an in-depth look at the design of Stratus with respect
to security and compliance with the NIH's controlled-access data policy.
Emphasis is placed on lessons learned while integrating OpenStack and Ceph
features into a so-called "walled garden", and how those technologies
influenced the security design. Many features of Stratus, including tiered
secure storage with the introduction of a controlled-access data "cache",
fault-tolerant live-migrations, and fully integrated two-factor authentication,
depend on recent OpenStack and Ceph features.Comment: 7 pages, 5 figures, PEARC '18: Practice and Experience in Advanced
Research Computing, July 22--26, 2018, Pittsburgh, PA, US
Extending DIRAC File Management with Erasure-Coding for efficient storage
The state of the art in Grid style data management is to achieve increased
resilience of data via multiple complete replicas of data files across multiple
storage endpoints. While this is effective, it is not the most space-efficient
approach to resilience, especially when the reliability of individual storage
endpoints is sufficiently high that only a few will be inactive at any point in
time. We report on work performed as part of GridPP\cite{GridPP}, extending the
Dirac File Catalogue and file management interface to allow the placement of
erasure-coded files: each file distributed as N identically-sized chunks of
data striped across a vector of storage endpoints, encoded such that any M
chunks can be lost and the original file can be reconstructed. The tools
developed are transparent to the user, and, as well as allowing up and
downloading of data to Grid storage, also provide the possibility of
parallelising access across all of the distributed chunks at once, improving
data transfer and IO performance. We expect this approach to be of most
interest to smaller VOs, who have tighter bounds on the storage available to
them, but larger (WLCG) VOs may be interested as their total data increases
during Run 2. We provide an analysis of the costs and benefits of the approach,
along with future development and implementation plans in this area. In
general, overheads for multiple file transfers provide the largest issue for
competitiveness of this approach at present.Comment: 21st International Conference on Computing for High Energy and
Nuclear Physics (CHEP2015
File-based storage of Digital Objects and constituent datastreams: XMLtapes and Internet Archive ARC files
This paper introduces the write-once/read-many XMLtape/ARC storage approach
for Digital Objects and their constituent datastreams. The approach combines
two interconnected file-based storage mechanisms that are made accessible in a
protocol-based manner. First, XML-based representations of multiple Digital
Objects are concatenated into a single file named an XMLtape. An XMLtape is a
valid XML file; its format definition is independent of the choice of the
XML-based complex object format by which Digital Objects are represented. The
creation of indexes for both the identifier and the creation datetime of the
XML-based representation of the Digital Objects facilitates OAI-PMH-based
access to Digital Objects stored in an XMLtape. Second, ARC files, as
introduced by the Internet Archive, are used to contain the constituent
datastreams of the Digital Objects in a concatenated manner. An index for the
identifier of the datastream facilitates OpenURL-based access to an ARC file.
The interconnection between XMLtapes and ARC files is provided by conveying the
identifiers of ARC files associated with an XMLtape as administrative
information in the XMLtape, and by including OpenURL references to constituent
datastreams of a Digital Object in the XML-based representation of that Digital
Object.Comment: 12 pages, 1 figures (camera-ready copy for ECDL 2005
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