Degrees of tenant isolation for cloud-hosted software services : a
cross-case analysis

Ochei, LC; Bass, J; Petrovski, A

Abstract

A challenge, when implementing multi-tenancy
in a cloud-hosted software service, is how to ensure that the
performance and resource consumption of one tenant does
not adversely affect other tenants. Software designers and
architects must achieve an optimal degree of tenant isolation
for their chosen application requirements. The objective
of this research is to reveal the trade-offs, commonalities,
and differences to be considered when implementing
the required degree of tenant isolation. This research uses
a cross-case analysis of selected open source cloud-hosted
software engineering tools to empirically evaluate varying
degrees of isolation between tenants. Our research reveals
five commonalities across the case studies: disk space reduction,
use of locking, low cloud resource consumption,
customization and use of plug-in architecture, and choice of
multi-tenancy pattern. Two of these common factors compromise
tenant isolation. The degree of isolation is reduced
when there is no strategy to reduce disk space and customization
and plug-in architecture is not adopted. In contrast,
the degree of isolation improves when careful consideration
is given to how to handle a high workload, locking of
data and processes is used to prevent clashes between multiple
tenants and selection of appropriate multi-tenancy pattern. The research also revealed five case study differences:
size of generated data, cloud resource consumption, sensitivity
to workload changes, the effect of the software process,
client latency and bandwidth, and type of software process.
The degree of isolation is impaired, in our results, by
the large size of generated data, high resource consumption
by certain software processes, high or fluctuating workload,
low client latency, and bandwidth when transferring multiple
files between repositories. Additionally, this research
provides a novel explanatory framework for (i) mapping tenant
isolation to different software development processes,
cloud resources and layers of the cloud stack; and (ii) explaining
the different trade-offs to consider affecting tenant
isolation (i.e. resource sharing, the number of users/requests,
customizability, the size of generated data, the scope of control
of the cloud application stack and business constraints)
when implementing multi-tenant cloud-hosted software services.
This research suggests that software architects have
to pay attention to the trade-offs, commonalities, and differences
we identify to achieve their degree of tenant isolation
requirements.

Citation

cross-case analysis. Journal of Cloud Computing: Advances, Systems and Applications, 7(22), https://doi.org/10.1186/s13677-018-0121-8

• Journal Article Type: Article
• Acceptance Date: Oct 25, 2018
• Online Publication Date: Dec 17, 2018
• Publication Date: Dec 17, 2018
• Deposit Date: Oct 25, 2018
• Publicly Available Date: Dec 17, 2018
• Journal: Journal of Cloud Computing : Advances, Systems and Applications
• Publisher: Springer Verlag
• Volume: 7
• Issue: 22
• DOI: https://doi.org/10.1186/s13677-018-0121-8
• Publisher URL: https://doi.org/10.1186/s13677-018-0121-8
• Related Public URLs: https://journalofcloudcomputing.springeropen.com/
• Additional Information: Funders : Tertiary Education Trust Fund (TETFUND), Nigeria;Robert Gordon University, UK