Scalability of RAID systems

RAID systems (Redundant Arrays of Inexpensive Disks) have dominated backend storage systems for more than two decades and have grown continuously in size and complexity. Currently they face unprecedented challenges from data intensive applications such as image processing, transaction processing and data warehousing. As the size of RAID systems increases, designers are faced with both performance and reliability challenges. These challenges include limited back-end network bandwidth, physical interconnect failures, correlated disk failures and long disk reconstruction time. This thesis studies the scalability of RAID systems in terms of both performance and reliability through simulation, using a discrete event driven simulator for RAID systems (SIMRAID) developed as part of this project. SIMRAID incorporates two benchmark workload generators, based on the SPC-1 and Iometer benchmark specifications. Each component of SIMRAID is highly parameterised, enabling it to explore a large design space. To improve the simulation speed, SIMRAID develops a set of abstraction techniques to extract the behaviour of the interconnection protocol without losing accuracy. Finally, to meet the technology trend toward heterogeneous storage architectures, SIMRAID develops a framework that allows easy modelling of different types of device and interconnection technique. Simulation experiments were first carried out on performance aspects of scalability. They were designed to answer two questions: (1) given a number of disks, which factors affect back-end network bandwidth requirements; (2) given an interconnection network, how many disks can be connected to the system. The results show that the bandwidth requirement per disk is primarily determined by workload features and stripe unit size (a smaller stripe unit size has better scalability than a larger one), with cache size and RAID algorithm having very little effect on this value. The maximum number of disks is limited, as would be expected, by the back-end network bandwidth. Studies of reliability have led to three proposals to improve the reliability and scalability of RAID systems. Firstly, a novel data layout called PCDSDF is proposed. PCDSDF combines the advantages of orthogonal data layouts and parity declustering data layouts, so that it can not only survivemultiple disk failures caused by physical interconnect failures or correlated disk failures, but also has a good degraded and rebuild performance. The generating process of PCDSDF is deterministic and time-efficient. The number of stripes per rotation (namely the number of stripes to achieve rebuild workload balance) is small. Analysis shows that the PCDSDF data layout can significantly improve the system reliability. Simulations performed on SIMRAID confirm the good performance of PCDSDF, which is comparable to other parity declustering data layouts, such as RELPR. Secondly, a system architecture and rebuilding mechanism have been designed, aimed at fast disk reconstruction. This architecture is based on parity declustering data layouts and a disk-oriented reconstruction algorithm. It uses stripe groups instead of stripes as the basic distribution unit so that it can make use of the sequential nature of the rebuilding workload. The design space of system factors such as parity declustering ratio, chunk size, private buffer size of surviving disks and free buffer size are explored to provide guidelines for storage system design. Thirdly, an efficient distributed hot spare allocation and assignment algorithm for general parity declustering data layouts has been developed. This algorithm avoids conflict problems in the process of assigning distributed spare space for the units on the failed disk. Simulation results show that it effectively solves the write bottleneck problem and, at the same time, there is only a small increase in the average response time to user requests

Performance analysis of disk mirroring techniques

Unequaled improvements in processor and I/O speeds make many applications such as databases and operating systems to be increasingly I/O bound. Many schemes such as disk caching and disk mirroring have been proposed to address the problem. In this thesis we focus only on disk mirroring. In disk mirroring, a logical disk image is maintained on two physical disks allowing a single disk failure to be transparent to application programs. Although disk mirroring improves data availability and reliability, it has two major drawbacks. First, writes are expensive because both disks must be updated. Second, load balancing during failure mode operation is poor because all requests are serviced by the surviving disk. Distorted mirrors was proposed to address the write problem and interleaved declustering to address the load balancing problem. In this thesis we perform a comparative study of these two schemes under various operating modes. In addition we also study traditional mirroring to provide a common basis for comparison

Writing (in) the Spaces of the Blitz: Spatial Myths and Memory in Wartime British Literature.

This dissertation examines the literary response to the Second World War and the Blitz in Britain. I argue that the physical spaces and landscapes of wartime Britain offered writers a metaphorical vocabulary for addressing war’s devastating consequences and imagining a possible future. From the late 1930s to the early 1950s, experimental, popular, and amateur writers alike responded to the extreme circumstances of aerial attack in innovative ways that reveal an unexpected convergence in the preoccupations of modernist highbrow and routine middlebrow writing in a time of war. A comprehensive study of Blitz writing substantially alters narratives of midcentury modernism, war writing, and British literary history. Blitz writers, generating a new type of battlefield text by and about non-soldiers, remade the physical spaces of England and transformed their symbolic value. In their work, air raid shelters, bombsites, and ruins become new catalysts for social and ideological encounters, which are also played out in more traditional literary spaces. Houses and domestic space are thrust from the private into the public sphere and lose their reassuring associations under threat of destruction. Bombed London and its urban spaces seem threatening and unreal, demanding imaginative rebuilding. The countryside invites a return to pastoral imagery as a way to address the war’s challenge to English history and identity. Texts that demonstrate the complex memory work associated with these spaces include Elizabeth Bowen’s The Heat of the Day, Rumer Godden’s A Fugue in Time, Henry Green’s Caught, Graham Greene’s The End of the Affair, Patrick Hamilton’s The Slaves of Solitude, James Hanley’s No Directions, Rose Macaulay’s The World My Wilderness, Mollie Panter-Downes’s One Fine Day, and Virginia Woolf’s Between the Acts, along with lesser-known poetry, fiction, diaries, journalism, and propaganda. This project uses such texts to reconstruct a literary geography of the home-front experience in World War II Britain and create a memorial landscape that recalls how the air raids and bombings were understood and remembered during and immediately after the war.PhDEnglish Language & LiteratureUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/107223/1/kefisher_1.pd

Dramatic Renditions: Battle Murals and the Struggle for Elite Legitimacy in Epiclassic Mesoamerica

Martial and bellicose imagery, as it commonly occurred in Mesoamerican monumental art, was almost universally reductive and allusive. It can be divided into a few major categories that are notable for their stability over two millennia and across the distinct, yet interrelated cultures of the region: emblematic motifs, solitary or processional warrior figures, individual debased captive figures, and captor-captive pairs. Depictions of actual battles, however, were notably rare. The handful of surviving examples - murals from the sites of Bonampak, Cacaxtla, Chichén Itzá, and Mulchic - are among the masterpieces of Precolumbian painting. The unprecedented dramatic complexity and heightened narrativity of these battle scenes - qualities produced by the presence of pictorial elements including action, specificity, variation, integration, and naturalism - contribute to a marked difference in their implicit content compared with other, more iconic artworks referencing warfare and militarism. Although these paintings are found at geographically distant sites and are stylistically unrelated, their approximate contemporaneity suggests that the brief, unprecedented appearance of battle murals in Mesoamerica was directly related to the widespread socio-political upheavals associated with the decline of Teotihuacan and the Classic Maya collapse during the Epiclassic period (c. 650 - 1050 A.D.), the time at which they were created. Their direct showcasing of feats of bravery and military prowess - both those of the rulers themselves and of their numerous allies and supporters - indicates a significant shift in the way legitimized authority was conceived during this period. Additionally, the radically different conception of temporality underlying these images points to an erosion in the unique status claimed by rulers with regard to the marking, and perhaps even the production of time. The fact that such violent tableaus were no longer produced during the documentedly militaristic Postclassic period reaffirms that, rather than directly reflecting social realities, monumental art projects a constructed image of legitimized authority. Nevertheless, an analysis of the functional characteristics of these artworks and the reconstruction of their implicit messages provide evidence with regard to the bases upon which rulership was conceived to be established during the Epiclassic

Graphic sensations: Vogue and the politics of the body, 1930-1945

This dissertation analyzes the visual program and material body of American Vogue magazine, a publication dedicated to the modern woman, during two tumultuous decades before the mid-century. In the 1930s, images of the female body, as well as the composition of the page, radically changed, as snapshots, streamlined design, and modern dress reform energized the look and experience of reading Vogue. As the next decade brought war, Vogue documented men and women in the American Armed Forces stationed in Europe and transmitted images of burned, mutilated, and broken bodies back to readers at home. Cover photographs of active, healthy women in the 1930s would shift to highly stylized, fractured images of the female form in the 1940s. The visual modifications to Vogue in the 1930s and 1940s were not merely aesthetic, but heavily inflected by shifting cultural, social, and economic norms during the Great Depression and the Second World War. Analyzing images by key Vogue photographers such as Toni Frissell, Lee Miller, and Erwin Blumenfeld in relation to page layouts, typography, clothing design, and popular culture, this project uncovers how photography and design promoted new strategies to connect with white female communities and articulate evolving definitions of the body and subjectivity. I argue the photographers and art directors under consideration here enhanced the concept of the magazine as a haptic medium by creating visual forms that privileged sensorial connections. Whereas fashion magazines have traditionally been undervalued in academic scholarship, this dissertation draws on feminist theory and studies of materiality to situate Vogue as a crucial object for understanding how the politics of the body shaped mass media, as the magazine fashioned new perceptual experiences for engaging with, and translating, modern women and forms of femininity

The Archaeology of Castle Slighting in the Middle Ages

Medieval castle slighting is the phenomenon in which a high-status fortification is demolished in a time of conflict. At its heart are issues about symbolism, the role of castles in medieval society, and the politics of power. Although examples can be found throughout the Middle Ages (1066–1500) in England, Wales and Scotland there has been no systematic study of the archaeology of castle slighting. Understanding castle slighting enhances our view of medieval society and how it responded to power struggles. This study interrogates the archaeological record to establish the nature of castle slighting: establishing how prevalent it was chronologically and geographically; which parts of castles were most likely to be slighted and why this is significant; the effects on the immediate landscape; and the wider role of destruction in medieval society. The contribution of archaeology is especially important as contemporary records give little information about this phenomenon. Using information recovered from excavation and survey allows this thesis to challenge existing narratives about slighting, especially with reference to the civil war between Stephen and Matilda (1139–1154) and the view that slighting was primarily to prevent an enemy from using a fortification. The thesis proposes a new framework for understanding how slighting is represented in the archaeological record and how it might be recognised in the future. Using this methodology, a total of 60 sites were identified. Slighting often coincides with periods of civil war, illustrating the importance of slighting as a tool of social control and the re-assertion of authority in the face of rebellion. Slighting did not necessarily encompass an entire site some parts of the castle – halls and chapels – were typically deliberately excluded from the destruction. There are also examples which fit the old narrative that slighting was used to prevent a fortification falling into enemy hands, but these cases are in the minority and are typically restricted to Scotland during the Scottish Wars of Independence. Given the castle’s role in shaping the landscape – acting as a focus for seigneurial power and precipitating the creation and growth of towns – it is important to understand how slighting effected nearby associated settlements. The evidence suggests that larger towns were able to prosper despite the disruption of slighting while smaller settlements were more likely to decline into obscurity. Importantly towns themselves were very rarely included in the destruction of slighting

A Combat Artist in World War II

Many artists have fought in wars, and renowned painters have recorded heroic scenes of great battles, but those works were usually done long after the battles were waged. Artists have also been commissioned to visit, briefly, war-torn areas and make notes of the devastation and horror. Yet few artists who were members of any armed services have drawn or painted daily while they fought alongside their comrades. Edward Reep, as an official combat artist in World War II, painted and sketched while the battles of the Italian campaign raged around him. He was shelled, mortared, and strafed. At Monte Cassino, the earth trembled as he attempted to paint the historic bombing of that magnificent abbey. Later, racing into Milan with armed partisans on the fenders of his Jeep, he saw the bodies of Mussolini and his beautiful mistress cut down from the gas station where they had been hanged by their heels. That same day he witnessed at first hand the spectacle of a large German army force holed up in a high-rise office tower, waiting for the chance to surrender to the proper American brass for fear of falling into the hands of the vengeful partisans. Reep\u27s recollections of such desperate days are made more memorable in Combat Artist by the many painfully vivid paintings and drawings that accompany the text. Reep\u27s battlefield drawings show us, with unrelenting honesty, the horrors and griefs—and the bitter comedy—of that war fought to end wars that only spawned more. Edward Reep is professor of painting emeritus at East Carolina University and the author of a number of books, including The Content of Watercolor.https://uknowledge.uky.edu/upk_military_history/1012/thumbnail.jp

Deportations in the Nazi Era

During the Nazi era, about three million Jews and tens of thousands of Sinti and Roma were deported to ghettos, camps, and extermination centers, where most of them were murdered. In over 20 contributions, scholars from different countries examine the deportations through a variety of perspectives and questions, with a special emphasis on the discussion of historical source material

Conventions Were Outraged: Country, House, Fiction

The dissertation traces intersections among subjectivity, gender, desire, and nation in English country house novels from 1921 to 1949. Inter-war and wartime fiction by Daphne du Maurier, Virginia Woolf, Nancy Mitford, P. G. Wodehouse, Elizabeth Bowen, and Evelyn Waugh performs and critiques conventional domestic ideals and, by extension, interrupts the discourses of power that underpin militaristic political certainties. I consider country house novels to be campy endorsements of the English home, in which characters can reimagine, but not escape, their roles within mythologized domestic and national spaces. The Introduction correlates theoretical critiques of nationalism, class, and gender to illuminate continuities among the naïve patriotism of the country house novel and its ironic figurations of rigid class and gender categories. Chapter 1 provides generic and critical contexts through a study of du Maurier’s Rebecca, in which the narrator’s subversion of social hierarchies relies upon the persistence, however ironic, of patriarchal nationalism. That queer desire is the necessary center around which oppressive norms operate only partially mitigates their force. Chapter 2 examines figures of absence in “A Haunted House,” To the Lighthouse, and Orlando. Woolf’s queering of the country house novel relies upon her Gothic figuration of Englishness, in which characters are only included within nationalist spaces by virtue of their exclusion. In Chapter 3, continuities between Orlando and Between the Acts test Woolf’s call to “indifference” to war in Three Guineas. The country house reifies the nostalgic crisis of Woolf’s feminist pacifism: political agency must occupy the borderland between nostalgic idealism and cynical self-abnegation. Chapter 4 examines popular country house novels by Wodehouse, Mitford, Bowen, and Waugh that explicitly engage, with various degrees of seriousness, with political conflicts of the 1930s and ’40s. Exposing disavowed affinities among the country house ethos, English patriotism, and fascist nostalgia provides opportunities to negotiate, if not resolve, ethical quandaries of wartime neutrality, irony, and indifference. By forcing readers to confront their own circumscription by nationalist and gendered expectations, these country house novels ultimately foreclose the possibility of escaping them – but they also demand readers’ renewed commitment to figures of difference and narratives of failure