מאמרי מחקר

In April 2009, Computerworld invited IT and business leaders to participate in a survey on desktop virtualization. The survey was fielded via targeted broadcasts to Computerworld customers, as well as through an invitation on Computerworld.com. The goal of the survey was to understand key drivers for implementing Virtual Desktop Infrastructure (VDI) or hosted virtual desktops, as well as top concerns in this area.

The statistical bases for current models of RAID reliability are reviewed, and a highly accurate alternative is provided and justified. This new model corrects statistical errors associated with the pervasive assumption that system (RAID group) times-to-failure follow a homogeneous Poisson process, and it corrects errors associated with the assumption that the time-to-failure and time-to-restore distributions are exponentially distributed. Statistical justification for the new model uses theories of reliability of repairable systems. Four critical component distributions are developed from field data. These distributions are for times to catastrophic failure, reconstruction and restoration, read errors, and disk data scrubs. Model results have been verified to predict between 2 and 1,500 times as many double disk failures as estimates made using the mean time-to-data-loss (MTTDL) method. Model results are compared to system-level field data for a RAID group of 14 drives and show excellent correlation and greater accuracy than either MTTDL or Markov models.

In this paper we present the analysis of two large-scale network file system workloads. We measured CIFS traffic for two enterprise-class file servers deployed in the NetApp data center for a three month period. One file server was used by marketing, sales, and finance departments and the other by the engineering department. Together these systems represent over 22TB of storage used by over 1500 employees, making this the first ever large-scale study of the CIFS protocol.

A collection of the latest NetApp Research Papers bound in a single volume.

This article presents an automated technique for visualizing large software architectures using multiple graphical representations, including multi-dimensional scaling, 2-D grid, and spiral layouts. We describe how our software visualization methods were applied to the Network Appliance operating system known as Data ONTAP 7G (ONTAP). We show how each method can be applied to comprehend a specific aspect of ONTAP. This approach can be used by software engineers, architects, and developers to better understand the architecture of their code.

This report analyzes the failure characteristics of storage subsystems. More specifically, we analyzed the NetApp AutoSupport logs collected from about 39,000 storage systems commercially deployed at various customer sites. The data set covers a period of 44 months and includes about 1,800,000 disks hosted in about 155,000 storage shelf enclosures.

In this paper, we present the design and implementation of SWEEPER architecture and backup copy selection algorithms that specifically tackle the problem of quickly and systematically identifying a good recovery point.

We introduce and apply a formal method of analyzing the design of data protection strategies. Specifically, we use moDelete checking to evaluate whether common protection techniques used in parity-based RAID systems are sufficient in light of the increasingly complex failure modes of modern disk drives.

This paper analyzes the failure characteristics of storage subsystems. More speci cally, we analyzed the storage logs collected from about 39,000 storage systems commercially deployed at various customer sites. The data set covers a period of 44 months and includes about 1,800,000 disks hosted in about 155,000 storage shelf enclosures.

In this paper, we present the first large-scale study of data corruption. We analyze corruption instances recorded in production storage systems containing a total of 1.53 million disk drives, over a period of 41 months. We study three classes of corruption: checksum mismatches, identity discrepancies, and parity inconsistencies