11,939 research outputs found
Tools for modelling and simulating migration-based preservation
This report describes two tools for modelling and simulating the costs and risks of using IT storage systems for the long-term archiving of file-based AV assets. The tools include a model of storage costs, the ingest and access of files, the possibility of data corruption and loss from a range of mechanisms, and the impact of having limited resources with which to fulfill access requests and preservation actions. Applications include archive planning, development of a technology strategy, cost estimation for business planning, operational decision support, staff training and generally promoting awareness of the issues and challenges archives face in digital preservation
Self-Repairing Disk Arrays
As the prices of magnetic storage continue to decrease, the cost of replacing
failed disks becomes increasingly dominated by the cost of the service call
itself. We propose to eliminate these calls by building disk arrays that
contain enough spare disks to operate without any human intervention during
their whole lifetime. To evaluate the feasibility of this approach, we have
simulated the behavior of two-dimensional disk arrays with n parity disks and
n(n-1)/2 data disks under realistic failure and repair assumptions. Our
conclusion is that having n(n+1)/2 spare disks is more than enough to achieve a
99.999 percent probability of not losing data over four years. We observe that
the same objectives cannot be reached with RAID level 6 organizations and would
require RAID stripes that could tolerate triple disk failures.Comment: Part of ADAPT Workshop proceedings, 2015 (arXiv:1412.2347
Performance comparison between iSCSI and other hardware and software solutions
We report on our investigations on some technologies that can be used to
build disk servers and networks of disk servers using commodity hardware and
software solutions. It focuses on the performance that can be achieved by these
systems and gives measured figures for different configurations.
It is divided into two parts : iSCSI and other technologies and hardware and
software RAID solutions.
The first part studies different technologies that can be used by clients to
access disk servers using a gigabit ethernet network. It covers block access
technologies (iSCSI, hyperSCSI, ENBD). Experimental figures are given for
different numbers of clients and servers.
The second part compares a system based on 3ware hardware RAID controllers, a
system using linux software RAID and IDE cards and a system mixing both
hardware RAID and software RAID. Performance measurements for reading and
writing are given for different RAID levels.Comment: Paper associated to a poster from the 2003 Computing in High Energy
and Nuclear Physics (CHEP03), La Jolla, Ca, USA, March 2003, 4 pages, LaTeX.
PSN TUDP00
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
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