PROV-TE: A Provenance-Driven Diagnostic Framework for Task Eviction in Data Centers

Cloud Computing allows users to control substantial computing power for complex data processing, generating huge and complex data. However, the virtual resources requested by users are rarely utilized to their full capacities. To mitigate this, providers often perform over-commitment to maximize profit, which can result in node overloading and consequent task eviction. This paper presents a novel framework that mines the huge and growing historical usage data generated by Cloud data centers to identify the causes of overloads. Provenance modelling is applied to add contextual meaning to the data, and the PROV-TE diagnostic framework provides algorithms to efficiently identify the causality of task eviction. Using simulation to reflect real world scenarios, our results demonstrate a precision and recall of the diagnostic algorithms of 83% and 90% respectively. This demonstrates a high level of accuracy of the identification of causes

Multi-tenancy in cloud computing

As Cloud Computing becomes the trend of information technology computational model, the Cloud security is becoming a major issue in adopting the Cloud where security is considered one of the most critical concerns for the large customers of Cloud (i.e. governments and enterprises). Such valid concern is mainly driven by the Multi-Tenancy situation which refers to resource sharing in Cloud Computing and its associated risks where confidentiality and/or integrity could be violated. As a result, security concerns may harness the advancement of Cloud Computing in the market. So, in order to propose effective security solutions and strategies a good knowledge of the current Cloud implementations and practices, especially the public Clouds, must be understood by professionals. Such understanding is needed in order to recognize attack vectors and attack surfaces. In this paper we will propose an attack model based on a threat model designed to take advantage of Multi-Tenancy situation only. Before that, a clear understanding of Multi-Tenancy, its origin and its benefits will be demonstrated. Also, a novel way on how to approach Multi-Tenancy will be illustrated. Finally, we will try to sense any suspicious behavior that may indicate to a possible attack where we will try to recognize the proposed attack model empirically from Google trace logs. Google trace logs are a 29-day worth of data released by Google. The data set was utilized in reliability and power consumption studies, but not been utilized in any security study to the extent of our knowledge

An investigation of how manipulation of Mycobacterium tuberculosis lipid body content impacts early infection of macrophages

Background: Lipid bodies (LBs), intracellular accumulations of triacylglycerol (TAG) are prominent features of Mycobacterium tuberculosis (Mtb) in the sputum of tuberculosis patients. TAG LBs form with growth arrest and are assimilated on regrowth. TAG is also found in the cell envelope and changes may impact cell surface hydrophobicity (CSH). How TAG LB content, CSH, and growth state affect early interactions between Mtb and macrophages is unknown. Methods: Mtb CDC1551 wild-type (WT) and transposon mutants with disrupted genes involved in TAG accumulation (tgs1::Tn) and assimilation (lipY::Tn) were investigated. Strains were assessed during culture and following treatment with nitric oxide/oleic acid (NO/OA) to promote LB accumulation. LB content (%LB), assessed by fluorescence microscopy, and CSH by hexadecane partitioning, were used to characterise the strains. These were then used to infect THP-1 macrophages with an assessment of uptake and early bacterial growth. Results: Mtb CDC1551 WT responded to NO/OA by increasing tgs1 expression, %LB and CSH, with levels returning to baseline 24h post-induction. Tgs1::Tn showed reduced growth with a similar %LB content as WT, however, it failed to accumulate LB on NO/OA induction and had reduced CSH. Tgs1::Tn prepared from growing Sauton’s culture, showed greater intracellular growth than WT, however, following NO/OA induction, the growth of both strains was similar. LipY::Tn had an increased growth rate and %LB compared with WT in Sauton’s culture. LipY::Tn increased %LB content and CSH with NO/OA induction, but unlike WT, did not show a return to baseline levels 24h post-induction. LipY::Tn from growing culture, or 24h post-NO/OA exposure, had greater intracellular growth compared with the WT. Although transcriptional complementation of tgs1 and lipY was demonstrated, restoration to the WT phenotype was not observed. Conclusions: Tgs1 and lipY mutation had a significant impact on growth, %LB and response to NO/OA. CSH and %LB did not relate to macrophage uptake and intracellular growth.</p